Bio-Medical Materials and Engineering

The International Conference on Biomedical Engineering and Biotechnology (ICBEB) is an international meeting held once a year. This, the fourth International Conference on Biomedical Engineering and Biotechnology (ICBEB2015), will be held in Shanghai, China, during August 18th–21st, 2015. This annual conference intends to provide an opportunity for researchers and practitioners at home and abroad to present the most recent frontiers and future challenges in the fields of biomedical science, biomedical engineering, biomaterials, bioinformatics and computational biology, biomedical imaging and signal processing, biomechanical engineering and biotechnology, etc. The papers published in this issue are selected from this Conference, which witness the advances in biomedical engineering and biotechnology during 2014–2015.

The purpose of this study is to compare the differences in flexural strength and compressive strength between four resin-modified luting glass ionomer cements that are commonly used in clinics. Furthermore, this study investigates the influence of curing mode on the flexural strength and compressive strength of dual-cured resin-modified glass ionomer cements. Initially, flexural strength and compressive strength test specimens were prepared for RL, NR, GCP, and GCC. The RL group and NR group were cured by the light-curing mode and chemical-curing mode. Five specimens were prepared for each test group, and the flexural strength and compressive strength of each were measured. Data were analyzed by one-way ANOVA with SPSS 13.0. Furthermore, the fracture morphology of the flexural specimens was observed by SEM. The result of the mean flexural strength of each group is as follows: the NR light-cured group > NR chemically-cured group > GCP > RL light-cured group > GCC > RL chemically-cured group. More specifically, the flexural strength of the NR light-cured group ((42.903±4.242) MPa) is significantly higher (P<0.05) than those of the other groups, and in addition, the flexural strength of the light-curing mode is significantly higher (P<0. 05) than that of both the NR and RL chemically-cured groups. The result of the mean compressive strength of each group is as follows: GCP > NR chemically-cured group > NR light-cured group > GCC > RL light-cured group > RL chemically-cured group. Although the compressive strengths of the NR and GCP groups are higher than those of the GCC and RL groups, there are no significant differences (P>0.05) between NR and GCP, and no significant differences between GCC and RL. Furthermore, there are no significant differences (P>0.05) between the two curing modes on NR and RL. From the present study, it can be concluded that NR has superior flexural strength and compressive strength compared to the other three materials. Additionally, the curing mode can affect the flexural strength of dual-cured RMGIC because with the light-curing mode, the flexural strength is higher than with the chemical-curing mode. Therefore, light curing is an essential procedure when using dual-cured RMGIC in clinics.

Minimization of the peak stresses and fracture incidence induced by mastication function is considered critical in design of all-ceramic dental restorations, especially for cantilever fixed partial dentures (FPDs). The focus of this study is on developing a mechanically-sound optimal design for all-ceramic cantilever dental bridge in a posterior region. The topology optimization procedure in association with Extended Finite Element Method (XFEM) is implemented here to search for the best possible distribution of porcelain and zirconia materials in the bridge structure. The designs with different volume fractions of zirconia are considered. The results show that this new methodology is capable of improving FPD design by minimizing incidence of crack in comparison with the initial design. Potentially, it provides dental technicians with a new design tool to develop mechanically sound cantilever fixed partial dentures for more complicated clinical situation.

To improve the biocompatibility of PP monofilaments used for pelvic reconstruction mesh, natural pearl powders were introduced as fillers in the preparation of modified PP monofilaments. The mechanical properties the modified PP monofilaments were analyzed, followed by characterization by scanning electron microscopy (SEM). Then, the biocompatibilities of these samples were investigated by MTT assay. The results revealed that the tensile strength and elongation of the as-prepared PP monofilaments can satisfy the requirement. According to the SEM images, masses of pearl powder were observed on the surface of monofilaments, which may favor the cell growth. The MTT results and the confocal microscopical images indicated that the presence of pearl powder in PP monofilaments led to improved proliferation and growth of L929 and PIEC cells under the same conditions, suggesting that PP monofilaments modified by pearl powders have a great potential in the applications of pelvic reconstruction.

This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50±1 mm in diameter and 0.5±0.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% perceptibility threshold was 1.71ΔE₀₀ (r²=0.88) and the 50:50% acceptability threshold was 4.00 ΔE₀₀ (r²=0.89). Within the limitations of this study, 1.71/4.00 ΔE₀₀ could be used as perceptibility/acceptability thresholds for acrylic denture base resins.

Enzyme-linked Immunosorbent Assay or ELISA -based diagnostics are considered the gold standard in the demonstration of various immunological reaction including in the measurement of antibody response to infectious diseases and to support pathogen identification with application potential in infectious disease outbreaks and individual patients’ treatment and clinical care. The rapid prototyping of ELISA-based diagnostics using available 3D printing technologies provides an opportunity for a further exploration of this platform into immunodetection systems. In this study, a ‘3D-Well’ was designed and fabricated using available 3D printing platforms to have an increased surface area of more than 4 times for protein-surface adsorption compared to those of 96-well plates. The ease and rapidity in designing-product development-feedback cycle offered through 3D printing platforms provided an opportunity for its rapid assessment, in which a chemical etching process was used to make the surface hydrophilic followed by validation through the diagnostic performance of ELISA for infectious disease without modifying current laboratory practices for ELISA. The higher sensitivity of the 3D-Well (3-folds higher) compared to the 96-well ELISA provides a potential for the expansion of this technology towards miniaturization platforms to reduce time, volume of reagents and samples needed for laboratory or field diagnosis of infectious diseases including applications in other disciplines.

The unique micro porous structure of expanded polytetrafluoroethylene (ePTFE) that allows bio-integration for fixation, as well as overall mechanical integrity make it used successfully in a number of biomedical and clinical applications, which include the reconstruction of the pulmonary valve in in right ventricular outflow tract reconstruction (RVOT) operations. The objective of this study was to determine the effects of the thermal treatment on physical and mechanical properties of ePTFE membranes. ePTFE sheets were cut into 16 rectangle strips (10 mm by 60 mm) and evenly separated into 4 groups. One group was the blank control (group A), while the rest of the three groups (group B to D) were heated to 350°C and cooled to 24°C at different cooling rates (10°C/min, 20°C/min and rapid ambient air cooling) in a temperature controlled atmosphere. The mechanical and morphological characteristics of all the samples were tested using a tensile test machine and a scanning electron microscopy (SEM). The results show that the elastic modulus of group B to D was 24.95%, 33.45% and 72.76% higher than group A. The percentage elongation of groups B to D was found to be between 2.3% and 40.45% lower than group A. The proportion of pores in the ePTFE membrane was reduced following the thermal treatment. There were no morphology differences observed between groups B to D. In summary, the selection of cooling rate was important for preserving the mechanical properties of ePTFE membranes under thermal treatment. These findings may provide useful information for the preparation of molded ePTFE valve in RVOT operations.

The purpose of this study was to evaluate the bonding ability of four representative dentin-adhesive systems by applying the micro-shear bond strength (μ-SBS) test method and to evaluate the influence of adhesive area limitation on the bond strength. Two different adhesive application methods were used in the μ-SBS test (with and without adhesives area limitation), and four representative adhesive systems were used in this study. Each dentin surface was treated with one of the four representative adhesive systems, and with twenty samples per group (n=20), each of the four groups underwent a μ-SBS test. The results showed that the bond strength was significantly influenced by the adhesive application method (p<0.05), the adhesive type (p<0.05) and the interaction between the two factors (p<0.05). With regard to the four representative dentin-adhesive systems, 3-E&R has a much better bond quality compared to the other adhesive systems. Furthermore, the micro-shear bond strength test method of restricting the area of both the adhesive and the resin is more reliable for evaluating the bonding property of adhesives to dentin, and it is also adequate for comparing the different adhesives systems.

A novel artificial peroxidase (AP) with highly catalytic efficiency was designed using hexadecyl trimethyl ammonium bromide (CTAB, 3 mM) nano-micelles and bovine heart cytochrome c (Cyt c, 0.5 µM) in 100 mM, pH 8.0 phosphate buffer at 25°C. The catalytic rate (k_cat) and Michaelis-Menten (K_m) of the AP were determined to be 0.311 ± 0.013 s⁻¹ and 8.64 ± 0.6 µM. The catalytic efficiency was 0.0360 ± 0.0020 µM⁻¹s⁻¹ (about 50% the efficiency of native horseradish peroxidase). The Ultraviolet–visible spectrophotometer and Circular Dichroism techniques were applied to study the properties of the CTAB-Cyt c nano-micelle. Designed AP can be applied instead of native horseradish peroxidase.

The scavenging activity of polysaccharides from Lycium barbarum, Lentinus edodes and Ganoderma Lucidum Karst to DPPH free radicals was investigated. It was found that among the three polysaccharides, Lycium barbarum polysaccharides (LBP) exhibits the best scavenging activity. Polysaccharide loaded collagen membranes were prepared by mixing LBP with collagen, starch, glycerol, sodium carboxymethyl cellulose and glutaraldehyde. In vitro drug release from membranes was evaluated. With increasing the immersion time, the release rate first increases and then slows down. Meanwhile, the scavenging activity to DPPH radicals exhibits similar variation, in agreement with a good release effect of the membrane. The optimal formulation of collagen membrane and preparation parameters were obtained considering the overall properties and the scavenging activity to radicals.

In this study, self-assembly regenerated silk fibroin (RSF) nanofibers were prepared and observed by Atomic Force Microscope (AFM). Then RSF films containing nanospheres and nanofibers were prepared and dissolved with poly (L-lactide-co-ε-caprolactone) (PLCL) with a blending ratio of 30/70 in hexafluoro-2-propanol (HFIP). In order to determine whether different nanostructures in the solution influence the morphological, structural, and mechanical properties of the final electrospun materials, flat membranes were prepared and characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared (FT-IR), and mechanical testing. The secondary structure of as-spun materials with RSF nanofibers were not changed, however, the diameter of electrospun fibers decreased and tensile strength and elongation at breaks increased. Electrospun materials with RSF nanofibers have the potential to be used for skin, cartilage, and blood vessels because of their biocompatibility and improved mechanical properties.

A new fabrication process for designing nerve conduits with a porous ionic cross-linked alginate/chitosan composite for nervous regeneration could be prepared. New designed nerve conduits with a porous ionic cross-linked alginate/chitosan composite were developed for nervous regeneration. Nerve conduits (NCs) represent a promising alternative to conventional treatments for peripheral nerve repair. NCs composed of various polysaccharides such as sodium alginate were designed and prepared by lyophilization as potential matrices for tissue engineering. The use of a porous ionic cross-linked alginate/chitosan composite could provide penetration channels that would lead to the products’ increasing penetration rate properties. Furthermore, the use of a porous ionic cross-linked alginate/chitosan composite also has a highly cross-linked structure, which would give the products relatively good mechanical properties. Furthermore, the drug could be incorporated into nerve conduits as a new drug-carrying system for nerve regeneration because of its porous and cross-linked structures.

The calcium ferrite nano-particles (CaFe₂O₄ NPs) were synthesized using a sol-gel method for targeted drug delivery application. The proposed nano-particles were initially prepared by mixing calcium and iron nitrates that were added with citric acid in order to prevent agglomeration and subsequently calcined at a temperature of 550°C to obtain small particle size. The prepared nanoparticles were characterized by using an XRD (X-ray diffraction), which revealed the configuration of orthorhombic structures of the CaFe₂O₄ nano-particles. A crystallite size of ∼13.59 nm was obtained using a Scherer’s formula. Magnetic analysis using a VSM (Vibrating Sample Magnetometer analysis), revealed that the synthesized particles exhibited super-paramagnetic behavior having magnetization saturation of approximately 88.3emu/g. Detailed observation via the scanning electron microscopy (SEM) showed the calcium ferrite nano-particles were spherical in shape.

The infection in burn wounds covered by biologic dressings leads to wound deepening and chronic wounds. The introduction of silver nanoparticles (AgNPs) into biologic dressings is a beneficial method to prevent wound infection and simultaneously promote wound healing. In this study, an AgNP-loaded silk fibroin (SF)/carboxymethylchitosan (CMC) composite sponge was fabricated. AgNPs with a mean diameter of 4.9 nm was synthesized in SF solution in situ. While CMC was incorporated and chemically crosslinked, SF was insolubilized by ethanol annealing. SEM imaging determined that the AgNP-loaded SF/CMC sponge was more porous than the pure SF sponge. Anti-bacterial results, measured by disk-diffusion and bacterial suspension assay, showed that the AgNP-loaded SF/CMC sponge demonstrated effective anti-bacterial activity against S. aureus and P. aeruginosa, and that its anti-P. aeruginosa activity was higher than that of AQUACEL®; Ag. The introduction of CMC improved the water absorption capacity, retention ability, and water vapor transmission rate of the sponge, which are all important properties of wound dressings.

The security risk of magnesium alloys used as biodegradable implant material was evaluated in this study. Dose-response assessment was conducted by using toxicological data from authoritative public health agencies (World Health Organization) and assuming 1∼3 years of uniform corrosion. Through modification calculation, the tolerable corrosion rate of biodegradable magnesium alloys in vivo was proposed, which theoretically ensured the bio-safety of the degradation products. The tolerable limits corresponding to various component elements in magnesium alloys were considered separately, although there are deficits in the toxicological data of some component elements. The influence of corrosion on the strength of magnesium alloys was evaluated, which would contribute to the rationally utilization of magnesium alloys as degradable implant materials. This study illustrates that not only toxicological calculations but also mechanical performance should be taken into consideration when developing novel degradable metallic implant.

Clinical cases show that zirconia restoration could happen fracture by accident under overloading after using a period of time. The purpose of this study is to research mechanical behavior and predict lifetime of dental zirconia ceramics under cyclic normal contact loading with experiments. Cyclic normal contact loading test and three point bending test are carried on specimens made of two brands of dental zirconia ceramic to obtain flexure strength and damage degree after different number of loading cycles. By means of damage mechanics model, damage degree under different number of contact loading cycles are calculated according to flexure strength, and verified by SEM photographs of cross section morphology of zirconia ceramics specimen phenomenologically. Relation curve of damage degree and number of cycles is fitted by polynomial fitting, then the number of loading cycles can be concluded when the specimen is complete damage. Strength degradation of two brands dental zirconia ceramics are researched in vitro, and prediction method of contact fatigue lifetime is established.

Caused by acute radiation skin reaction and injury, receiving radiotherapy treatment process is often performed side-effects on cancer patients. The clinical manifestations of skin irritation, itching, peeling, pigmentation, ulcer bleeding and other symptoms, in addition to causing patient discomfort and affecting quality of life, may increase the risk of local or systemic infection, and lead to interruption of radiation therapy. At present, for acute radiation dermatitis, there is no uniform treatment, and the various methods are evaluated variously. In this study, the authors focus on broken pearls using room temperature super extraction system, the water extraction process of wet-grinding method, nano-scale pearl, along with a large number of high purity natural amino acid extracts in the water. The room-temperature super-extraction system (RTSES) can be extracted from a relatively high-volume of pearl extract. We use pearl extract as the main component of experimental material, and the blending of pearl extract and poly (γ-glutamic acid) is used to form biodegradable composite hydrogels. This study aims to evaluate the use of RTSES to extract the major active components of pearl and enhance their anti-inflammation and anti-apoptosis effects. The possible effect of pearl extract on inducing apoptosis in human keratinocyte cells (HaCaT) under the exposure of low dose UVB has been investigated. Various concentrations of pearl extracts have been used to study the effect of low dosage UVB on HaCaT cells. The results show that pearl extract has no toxic effect on HaCaT cells. Combining the pearl extract and poly (γ-glutamic acid) hydrogels with UVB irradiation would decrease the inflammation and apoptosis of HaCaT cells. The commercial pearl extract has the potential to inhibit radiation dermatitis occurring within keratinocyte cells.

Polylactic acid (PLA)/styrene-ethylene-butylene-styrene (SEBS) composites were prepared by melt blending. Differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WXRD) were used to characterize PLA and PLA/SEBS composites in terms of their melting behavior and crystallization. Curves from thermal gravimetric analysis (TGA) illustrated that thermostability increased with SEBS content. Further morphological analysis of PLA/SEBS composites revealed that SEBS molecules were not miscible with PLA molecules in PLA/SEBS composites. The tensile testing for PLA and PLA/SEBS composites showed that the elongation at the break was enhanced, but tensile strength decreased with increasing SEBS content. L929 fibroblast cells were chosen to assess the cytocompatibility; the cell growth of PLA was found to decrease with increasing SEBS content. This study proposes possible reasons for these properties of PLA/SEBS composites.

Surface roughness has been considered as an important influencing factor for cell response. The aim of this study was to find out whether MC3T3-E1 cells, a mouse osteoblast-like cell line, can sense the amplitudes of surface topography of titanium alloy (Ti6Al4V), and if surface-dependent cell morphology would be presented on the substrata with varied roughness. A series of polished samples (R_a: 0.30∼1.80 μm) were prepared to produce macroscopically parallel grooves using different grades of silicon carbide sandpaper (#100, #320, #600, #1000 and #2000). The experimental results indicated that the behavior and morphology of cells largely depended on the substrata where they were cultured. More efficient proliferation of MC3T3-E1 cells was shown on the surfaces with R_a of 0.50∼1.00 μm, with respect to either the rougher or the smoother specimens. Furthermore, MC3T3-E1 cells seeded on the Ti6Al4V surfaces within this narrow range responded to the increasing surface roughness with increased proliferation. Contact guidance of cells could be observed on the rougher specimens (R_a: 0.80∼1.00 μm), whereas more random orientations were exhibited for the adsorbed cells on the smoother surfaces (R_a: 0.50∼0.60 μm).

To investigate the inhibition effect of oxymatrine induces human lung cancer A549 cells apoptosis. The A549 cells were cultured for 24 h, than the various concentration of oxymatrine (2 mmol/L, 4 mmol/L, 8 mmol/L, 15 mmol/L) were added into different experimental group cells, and 5-fluorouracil were added into the positive control group cells for 12 h, 24 h, 36 h, 48 h respectively. The A549 cells inhibition rate, apoptosis, and the expression of Bcl-2 and Bax were examined by MTT method, Annexin V/PI double staining method, real-time quantitative PCR and western blot, respectively. At same time, the morphological changes of A549 cells were observed with an inverted microscope. In the range of 2 mmol/L∼15 mmol/L, oxymatrine had obvious inhibition effects on the proliferation of A549 cells. Compared with the negative control group, it has significantly different (P<0.01). There was remarkably the time- and dose-dependent correlation. After A549 cells were treated with 8 mmol/L oxymatrine for 24 h, the morphological change of cell apoptosis was observed and the extent of apoptosis was quantified by flow cytometry. Furthermore, the expression of Bcl-2 was reduced and the expression of Bax was increased remarkably (P<0.05). Oxymatrine has significant inhibition effects on the cells proliferation and the effects showed time-dependent and dose-dependent. Oxymatrine can induce apoptosis of the A549 cells by regulating the expression of Bcl-2 and Bax.

A novel technique and product for carpal tunnel microscopic surgical procedures using a modified medical device containing a head as a surgical scalpel under light guidance were designed and studied. The novel design of the medical device was developed and applied in a new carpal tunnel microscopic surgical procedure in place of the traditional carpal tunnel surgical procedure. Biological and clinical evaluations of carpal tunnel surgical procedure using the designed optically guided medical device were studied. For commercialized reasons, some guidance was considered, such as ISO 10993-1:2009(E), for the biological evaluation of the device. Furthermore, a clinical evaluation was carried out. The designed optically guided medical device could provide a powerful medical device for carpal tunnel syndrome and related applications.

The locking compression plate fixation treatment for the unstable sacral fractures is simple and effective, with less trauma and complications. Some locking compression plate parts have been made of high-strength Plate manufactured by hot stamping process since the demand for lightweight biomedical materials. Finite Element (FE) method of One-Step inverse forming based on deformation theory is the tool to evaluate the formability of locking compression plate panel quickly in initial design for reducing costs and development cycle of Plate. But current one-step inverse forming methods are all suitable for cold stamping, not hot-stamping. This paper proposed one-step inverse forming method and workflow for hot-stamping of locking compression Plate. And the B pillar of a sacral bone was simulated and its computing result was compared with experimental value. The result shows that the proposed method in this paper can quickly evaluate high temperature formability of high-strength Plate. And the method is proposed to be used in initial design.

The nervous system is an important regulator of the human body because it adapts our responses to the external environment and provides people the ability of thought, memory, and emotion. PC12 is a cell line that is commonly used to study the behavior of neural differentiation. PC12 cells further differentiate into nerve cells when stimulated by nerve growth factor (NGF), which have neurite, dendrite, and axon, and form synapses with neighboring cells to build neural networks. Micropatterns and electric stimulation can significantly influence cellular attachment, proliferation, orientation, extracellular matrix (ECM) expression, neural differentiation, and cellular motion. We fabricated polycaprolactone (PCL) nanofiber with or without carbon nanotubes (CNTs) by electrospinning and promoted the neural differentiation of PC12 cells by electric stimulation. We used scanning electron microscope (SEM) and fluorescence microscope to observe the NGF-induced growth of PC12 cells on PCL nanofiber. Axon formation and cellular activity expression, that confirm that PC12 cells can grow well on PCL nanofiber, and the gene expressions of MAP1b and GAP43 significantly increased after electric stimulation. Based on the results, the structure of nanofibers containing CNTs can effectively induce neural differentiation of PC12 cells in an electric field. This experimental model can be used for future clinical applications.

To determine the optimal ratio of nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) in the novel three-dimensional porous PLLA/n-HA composite scaffolds, low-temperature rapid prototyping technology was employed to fabricate the composite materials with different n-HA contents. Mechanical properties and degradation behaviors of the composites were examined, and the scaffold microstructure and n-HA dispersion were observed by scanning electron microscope (SEM). Mechanical tests demonstrated that the tensile strength of the composite material gradually decreased with an increase in n-HA content. When the n-HA content reached 20 wt%, the bending strength of the composite material peaked at 138.5 MPa. SEM images demonstrated that the optimal content of n-HA was 20 wt% as the largest interconnected pore size that can be seen, with a porosity as high as 80%. In vitro degradation experiments demonstrated that the pH value of the material containing solution gradually decreased in a time-dependent manner, with a simultaneous weakening of the mechanical properties. In vitro study using rat osteoblast cells showed that the composite scaffolds were biocompatible; the 20 wt% n-HA scaffold offered particular improvement to rat osteoblast cell adhesion and proliferation compared to other compositions. It was therefore concluded that 20 wt% n-HA is the optimal nano-hydroxyapatite (n-HA) to polylactic acid (PLLA) ratio, with promise for bone tissue engineering.

This paper presents a new method for real-time modelling soft tissue deformation. It improves the traditional mass-spring model with conical springs to deal with nonlinear mechanical behaviours of soft tissues. A conical spring model is developed to predict soft tissue deformation with reference to deformation patterns. The model parameters are formulated according to tissue deformation patterns and the nonlinear behaviours of soft tissues are modelled with the stiffness variation of conical spring. Experimental results show that the proposed method can describe different tissue deformation patterns using one single equation and also exhibit the typical mechanical behaviours of soft tissues.

A ureteral stenosis or occlusion causes the disturbance of normal urine flow and results in renal failure. Ureteral stents are used to relieve the stagnation of urine in the upper urinary tract. Peristalsis in the ureter, which occurs to help urine flow, becomes to weaken when a stent is inserted and effective peristalsis disappears as time goes on, and a stented ureter seems to be tubular and curved in the human body. Double J stents, which are manufactured by many medical companies and are used widely these days, have different geometries of side holes in the stent shafts. In total, 12 models—six curved models of a stented ureter according to different numbers and positions of side holes and ureteral and stent stenoses and another six straight models for comparison with the curved ones—were made based on the data collected from 19 men. The flow rate and pattern in the stented ureter were evaluated using computational fluid dynamics (CFD). According to the results, curved models reflecting the human anatomy seem to be more desirable in the CFD simulation of urine flow and must be good for evaluating the effect of geometrical variations in stent design on urine flow.

Flow diverter is a kind of stent-like devices with higher metal coverage rate, and it is deployed endovascularly to treat cerebral aneurysms, especially to treat giant aneurysms. However, there exist some arguments about its safety and efficacy. Hemodynamics is considered to play very important role during the initiation, growth and rupture of cerebral aneurysms. In this study, the models of a giant cerebral aneurysm involved a small branch at the aneurysmal sac before and after flow diverter implantation were constructed by virtual deployment, the blood flows in the models were simulated by computational fluid dynamics method. Analyzing the variations of the hemodynamics, the following conclusions were summarized. The flow diverter is very effective device to occlude the aneurysm, the flow rate at the small branch was rarely changed when the flow diverter deployed and the flow diverter.

Portal vein hypertension generally occurs in liver diseases like hepatic cirrhosis. It causes hemodynamic changes that are closely related to liver disease. At advanced stages of hepatic cirrhosis, portal vein hypertension leads to the atrophy of the right lobe of the liver and the hypertrophy of the left lobe through a process that has not yet been fully explained. Based on the hemodynamic changes that are known to occur, we hypothesize that liver volume is related to the distribution of blood flowing from the splenic vein (SV) that carries hepatotrophic factors from the spleen and pancreas. We studied blood flow in the portal vein system to validate this hypothesis through in vitro experimentation and a computational fluid dynamics (CFD) analysis involving both simplified and patient-specific models based on four healthy subjects and two patients with liver cirrhosis. The results confirmed the hypothesis that right-lobe atrophy is significantly influenced by the distribution of blood from the SV. Moreover, the patients with liver cirrhosis had a significantly larger mass fraction of spleen-derived blood in the left portal vein branch (LPV) than healthy subjects, a result consistent with right-lobe atrophy and left-lobe hypertrophy.

Three numerical models of an abdominal aortic aneurysm (AAA) with different geometric parameters are established in order to examine the coupled effect of the fluid-structure of AAA. The study is focused on examining the roles of the dilatation parameter and the aspect ratio of an AAA in the flow dynamic within a pulse period. The numerical results demonstrate that the vortex dominates the dynamic flow behavior within an AAA. During a pressure impulse cycle, an AAA is influenced by the entirety of the vortex, from its generation to its subsequent disappearance. As an indirect effect of the vortex dynamic acting on vessels, a series of alternate impulse responses of the wall shear stress (WSS) is generated in an AAA as eddies induced by the vortex move along the axis of the vessels, and the strength of the responses is proportional to the strength of the eddies. The alternated impulse of WSS may be one of the main influencing factors on AAA rupture. The results of this study aided in understanding the mechanisms underlying the evolutionary processes of AAAs.

The paper presents an application of the FSI technique to determine hemodynamics in the abdominal aorta (AA). To establish boundary conditions for the FSI study, MR anatomical data and 4D MRI velocity-mapping data (in three blood flow velocity directions and time) were collected to acquire realistic geometry of the AA and blood velocity. The mechanical parameters of the patient-specific aortic wall were applied in FSI simulations to describe wall mechanics and blood flow in the AA. Comparison of calculated and measured blood flow patterns and flow rate waveforms shows good agreement, which proves that wall pulsations should be incorporated into simulations that determine hemodynamics in the AA. The results of this work suggest that FSI analysis based on patient-specific data, such as the mechanical parameters of the aortic wall, real geometry of the aorta, and 4D flow information, might be used to predict the development of cardiovascular diseases.

The existence of large blood vessels seriously impacts the results of microwave ablation on heat transfer of surrounding tissue, and the research of influences about large blood vessels could be essential and significant. The temperature distribution in the tissue was analyzed with a microwave heating source by finite element method. The model, where the blood vessel is parallel to antenna, has different distances from antenna to blood vessel. As distance was greater than 20mm, the effect of blood vessel that was parallel to antenna was ignored and the ablation area was elliptical-like. When distance was less than 10mm, the part of asymmetrical coagulated area was on the right side of blood vessel. Therefore, the temperature contour by different conditions could provide numerical references, which is whether to block blood vessel or not, to achieve the aim of guiding the clinical practice, according to the locations of tumor and blood vessel.

Considering the blood coagulation induced by the heating of radio frequency ablation (RFA) and the mechanism of aneurysm embolization, we proposed that RFA may be used to treat arterial aneurysm. But the safety of this method should be investigated. A finite element method (FEM) was used to simulate temperature and pressure distribution in aneurysm with different electrode position, electric field intensity and ablation time. When the electrode is in the middle of the artery aneurysm sac, temperature rose clearly in half side of artery aneurysm, which is not suitable for RFA. Temperature rose in the whole aneurysm when the electrode is under the artery aneurysm orifice, which is suitable for the ablation therapy. And in this way, the highest temperature was 69.585°C when power was 5.0 V/mm with 60 s. It can promote the coagulation and thrombosis generation in the aneurysm sac while the outside tissue temperature rises a little. Meanwhile, the pressure (10 Pa) at the top of aneurysm sac with electrode insertion is less than that (60 Pa) without electrode, so electrode implant may protect the aneurysm from rupture. The results can provide a theoretical basis for interventional treatment of aneurysm with RFA.

Since the vessels in the biological tissues are characterized by low seepage Reynolds numbers and contracting or expanding walls, more attention is paid on the viscous flow outside the porous pipe with small expansion or contraction. This paper presents a numerical solution of the flow and heat transfer outside an expanding or contracting porous cylinder. The coupled nonlinear similarity equations are solved by Bvp4c, which is a collocation method with MATLAB. The effects of the different physical parameters, namely the permeability Reynolds number,the expansion ratio and the Prandtl number, on the velocity and temperature distribution are obtained and the results are shown graphically.

A method is proposed to determine the mechanical properties of retina based on in vivo experiments and numerical simulations. First, saline water was injected into the anterior chamber of the right eye of a cat to cause acute high intraocular pressure. After the eye was scanned using optical coherence tomography under different acute high intraocular pressures, the images of the retina in vivo were obtained and the thickness of the retina was calculated. Then, the three-dimensional structure of the optic nerve head including the retina and the choroid were reconstructed using image processing technology. Three different material models for the retina and the choroid were taken and the finite element models of the optic nerve head were constructed. Finally, an inverse method was proposed to determine the parameters of a constitutive model of the retina and of the choroid simultaneously. The results showed that the deformation of the retina can be properly simulated taking into consideration the nonlinear elastic properties of the retina and of the choroid.

Carotid atherosclerotic disease is highly related to cerebrovascular events. Carotid endarterectomy is the common operation method to treat this disease. In this study, hemodynamics analyses are performed on the carotid arteries in three patients, whose right carotid artery had been treated by carotid endarterectomy and the left carotid artery remained untreated. Flow and loading conditions are compared between these treated and untreated carotid arteries and evaluation of the operative results is discussed. Patient-specific models are reconstructed from MDCT data. Intraoperative ultrasound flow measurements are performed on the treated carotid arteries and the obtained data are used as the boundary conditions of the models and the validations of the computational results. Finite volume method is employed to solve the transport equations and the flow and loading conditions of the models are reported. The results indicate that: (i) in two of the three patients, the internal-to-external flow rate ratio in the untreated carotid artery is larger than that in the treated one, and the average overall flow split ratio by summing up the data of both the left and right carotid arteries is about 2.15; (ii) in the carotid bulb, high wall shear stress occurs at the bifurcation near the external carotid artery in all of the cases without hard plaques; (iii) the operated arteries present low time-averaged wall shear stress at the carotid bulb, especially for the treated arteries with patch technique, indicating the possibility of the recurrence of stenosis; (iv) high temporal gradient of wall shear stress (>35 Pa/s) is shown in the narrowing regions along the vessels; and (v) in the carotid arteries without serious stenosis, the maximum velocity magnitude during mid-diastole is 32∼37% of that at systolic peak, however, in the carotid artery with 50% stenosis by hard plaques, this value is nearly doubled (64%). The computational work quantifies flow and loading distributions in the treated and untreated carotid arteries of the same patient, contributing to evaluation of the operative results and indicating the recurrent sites of potential atheromatous plaques.

The study involved 300 elderly patients with chronic periapical periodontitis. The patients were randomly assigned into three groups. The treatment for group A used a Mtwo Ni-Ti rotary instrument combined with ultrasonic irrigation of a 2.5% NaOCl solution. The group B used the same instrument combined with ultrasonic irrigation of an active silver ion antibacterial solution. The group C used the same instrument combined with syringe irrigation of a 2.5% NaOCl solution. The root canal fillings were performed immediately after canal preparation. Twenty-four hours after the procedure, patients self-assessed pain levels according to the VAS table. The three groups returned after seven days so their postoperative acute reactions could be evaluated clinically. After six and twelve months, efficacy was evaluated. The self-assessed pain levels for group A and B were significantly lower than group C. The incidence of postoperative acute reactions after seven days for group A and B were significantly lower than those of group C. The effective rates after six and twelve months did not differ among these groups. The single-visit root canal treatment with a nickel-titanium rotary instrument combined with ultrasonic irrigation for elderly patients with chronic periapical periodontitis achieved short and long term efficacy and stability.

A double J stent has been used widely these days for patients with a ureteral stenosis or with renal stones and lithotripsy. The stent has multiple side holes in the shaft, which supply detours for urine flow. Even though medical companies produce various forms of double J stents that have different numbers and positions of side holes in the stent, the function of side holes in fluid dynamics has not been studied well. Here, the flow rate and pattern around the side holes of a double J stent were evaluated in curved models of a stented ureter based on the human anatomy and straight models for comparison. The total flow rate was higher in the stent with a greater number of side holes. The inflow and outflow to the stent through the side holes in the curved ureter was more active than in the straight ureter, which means the flow through side holes exists even in the ureter without ureteral stenosis or occlusion and even in the straight ureter. When the diameter of the ureter changed, the in-stent flow rate in the ureter did not change and the extraluminal flow rate was higher in the ureter with a greater diameter.

Wearable robotic devices provide safe and intensive rehabilitation, enabling repeated motions for motor function recovery in stroke patients. The aim of this small case series was to demonstrate the training effects of a three-week robotic leg orthosis, and to investigate possible mechanisms of the sensory-motor alterations and improvements by using gait analysis and EMG. Three survivors of chronic strokes participated in robot-assisted gait therapy for three weeks. EMG signals from the rectus femoris (RF), tibialis anterior (TA), biceps femoris (BF), and medial gastrocnemius (MG), as well as kinetics and kinematics data of the lower limb, were recorded before and after the training. The normalized root mean squared (RMS) values of the muscles, the joint moments, joint angles, and the results of two clinical scales (Berg Balance scale, BBS, and the lower extremity subscale of Fugl-Meyer assessment, LE-FMA) were used for analysis. All participants experienced improved balance and functional performances and increased BBS and LE-FMA scores. The EMG results showed there was an increase of the normalized RMS values of the MG and BF on the affected side. Additionally, EMG activities of the agonist and antagonist pair (i.e. RF and BF) appeared to return to similar levels after training. The peak moment of hip flexor, knee extensor, and plantar flexor, which all contributed to push-off power, were found to have increased after training. In summary, the three-week training period using the wearable RLO improved the three participants’ gait performance by regaining push-off power and improved muscle activation and walking speed.

In the area of manufacturing surgical instruments, the ability to rapidly design, prototype and test surgical instruments is critical. This paper provides a simple case study of the rapid development of two bio-mechanism based surgical instruments which are ergonomic, aesthetic and were successfully designed, prototyped and conceptually tested in a very short period of time.

A new rehabilitation robot was designed. The robot included a suspension mechanism, a drive unit, and an adjustment mechanism. Additionally, innovative weight loss mechanism increased the dynamical device so that it could be used with patients of varying lower extremity muscle strengths. The relationship of hip and knee angles with height, step length, and gait cycle was studied. It was developed to generate different trajectories for different patients. Kinematics and dynamics were studied to lay the foundation for control.

In this paper, we describe a new multi-mode telestimulation system for brain-microstimulation for the navigation of a robo-pigeon, a new type of bio-robot based on Brain-Computer Interface (BCI) techniques. The multi-mode telestimulation system overcomes neuron adaptation that was a key shortcoming of the previous single-mode stimulation by the use of non-steady TTL biphasic pulses accomplished by randomly alternating pulse modes. To improve efficiency, a new behavior model (“virtual fear”) is proposed and applied to the robo-pigeon. Unlike the previous “virtual reward” model, the “virtual fear” behavior model does not require special training. The performance and effectiveness of the system to alleviate the adaptation of neurons was verified by a robo-pigeon navigation test, simultaneously confirming the practicality of the “virtual fear” behavioral model.

A number of issues that exist in common fracture reduction surgeries can be mitigated by robot-assisted fracture reduction. However, the safety of patients and the performance of the robot, which are closely related to the muscle forces, are important indexes that restrict the development of robots. Though researchers have done a great deal of work on the biomechanics of the musculoskeletal system, the dynamics of the musculoskeletal system, particularly the aspects related to the function of the robot, is not well understood. For this reason, we represent the complex biological system by establishing a dynamic biomechanical model based on the Hill muscle model and the Kane method for the robot that we have developed and the musculoskeletal system. We analyzed the relationship between the motion and force of the bone fragments and the robot during a simulation of a robot-assisted fracture reduction. The influence of the muscle force on the robot system was predicted and managed. The simulation results provide a basis for a fracture reduction path plan that ensures patient safety and a useful reference for the mechanical design of the robot.

How to improve placement accuracy of needle insertion into liver tissue is of paramount interest to physicians. A robot-assisted system was developed to experimentally demonstrate its advantages in needle insertion surgeries. Experiments of needle insertion into porcine liver tissue were performed with conic tip needle (diameter 8 mm) and bevel tip needle (diameter 1.5 mm) in this study. Manual operation was designed to compare the performance of the presented robot-assisted system. The real-time force curves show outstanding advantages of robot-assisted operation in improving the controllability and stability of needle insertion process by comparing manual operation. The statistics of maximum force and average force further demonstrates robot-assisted operation causes less oscillation. The difference of liver deformation created by manual operation and robot-assisted operation is very low, 1 mm for average deformation and 2 mm for maximum deformation. To conclude, the presented robot-assisted system can improve placement accuracy of needle by stably control insertion process.

This case study describes the effects of a wearable dynamic knee orthosis to supplement walking training in a patient suffering knee hyperextension. The subject was a 57-year old female who was 3.5 years post-brain tumor surgery. She was presented with impaired right lower extremity muscle performance, increased lower extremity muscle tension, and right knee hyperextension. She reported pain at the right knee joint and tibialis anterior after 10 minutes of over-ground walk. Fifteen one-hour sessions of gait training with robotic knee orthosis (RKO) were provided an over 3 weeks period. The subject demonstrated improvement with right lower limb kinematic and kinetic measures of gait. Peak flexion degree and moment increased (from -4.99° to 13.47°, and from 0.18 Nm/kg to 0.20 Nm/kg respectively).Extension peak moment decreased from 1.03 Nm/kg to 0.53 Nm/kg. Knee joint force decreased from 0.68 N to 0.45 N. Ground reaction force (GRF) reduced from 11.06N to 10.11N. Berg Balance Scale (BBS) improved from 45/56 to 51/56. No difference was observed in Fugl-Meyer Assessment of the Lower limb (FMA-LE) scores. Gait training that integrates an intention-based RKO for correcting knee hyperextension can be clinically effective. The persistence and generalizability of these results need to be further investigated.

The measurement of volume pulse waves may be easily affected based on the measured position (different fingers or toes), body posture, as well as other factors. Therefore, interferences during measurement need to be removed. For this study, relevant parameters of volume pulse wave were obtained by changing the affecting factors. The data were analyzed in order to indicate the differences in volume pulse wave parameters among different fingers and toes in four postures. Results showed that when subjects were lying, inclined or in a sitting posture, volume pulse wave parameters of the index finger, middle finger and ring finger on both hands displayed no apparent differences. When subjects were in a sitting posture, volume pulse wave parameters of the big, second and third toes on both feet showed no significant differences.

A volume of research has been performed on the optical surface profilometry in the field of biomedicine and the optical system with the phase-measuring method becomes the main emphasis of the research. In this research, a brand new fringe projection profilometry with multiple frequencies is described for measuring the biological tissue. A pork liver, as an object, is regarded as a human organ and a DMD projector is used to generate the multi-frequency fringe patterns. The wrapped phase maps are obtained by means of the five-step phase shifting method and calculated via a peak searching algorithm in which the process of measuring the point on the surface of the object is independent so that the step of unwrapping the phase can be avoided. The final results given are acceptable which confirm this method and suggest its enormous potential for the biomedical measurements.

This study investigates the radiation safety of a newly designed magnetic induction sensor. This novel magnetic induction sensor uses a two-arm Archimedean spiral coil (TAASC) as the exciter. A human head model with a real anatomical structure was used to calculate the specific absorption rate (SAR) and temperature change. Computer Simulation Technology (CST) was used to determine the values of the peak 10-g SAR under different operating parameters (current, frequency, horizontal distance between the excitation coil and the receiver coil, vertical distance between the top of the head model and the XOY plane, position of excitation coil, and volume of hemorrhage). Then, the highest response for the SAR and temperature rise was determined. The results showed that this new magnetic induction sensor is safe in the initial state; for safety reasons, the TAASC current should not exceed 4 A. The scalp tissue absorbed most of the electromagnetic energy. The TAASC’s SAR/thermal performance was close to that of the circular coil.

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

Cavitation has great application potential in microvessel damage and targeted drug delivery. Concerning cavitation, droplet vaporization has been widely investigated in vitro and in vivo with plasmonic nanoparticles. Droplets with a liquid dodecafluoropentane (DDFP) core enclosed in an albumin shell have a stable and simple structure with good characteristics of laser absorbing; thus, DDFP droplets could be an effective aim for laser-induced cavitation. The DDPF droplet was prepared and perfused in a mimic microvessel in the optical microscopic system with a passive acoustic detection module. Three patterns of laser-induced cavitation in the droplets were observed. The emitted acoustic signals showed specific spectrum components at specific time points. It was suggested that a nanosecond laser pulse could induce cavitation in DDPF droplets, and specific acoustic signals would be emitted. Analyzing its characteristics could aid in monitoring the laser-induced cavitation process in droplets, which is meaningful to theranostic application.

Based on the electrical properties of biological tissues, bioimpedance measurement technology can be employed to collect physiologic and pathologic information by measuring changes in human bioimpedance. When an alternating current (AC) is applied as a detection signal to a tissue, the current field distribution, which is affected by skin effect, is related to both the bioimpedance of the tissue and the AC frequency. These relations would possibly reduce the accuracy and reliability of the measurement. In this study, an electromagnetic theory-based method, in which cylindrical conductor were divided into layers, was used to obtain current field distribution models of human limbs. Model simulations were conducted in MATLAB. The skin effect phenomenon and its characteristics in human tissues at different frequencies were observed, thus providing essential data on skin effect, which are useful in the development of bioimpedance measurement technology.

Thus far, the measurement of dielectric properties of biological tissues has been achieved on the assumption that the biological tissues are homogeneous. In fact, most tissues should be heterogeneous because there are many small structures included in these tissues, such as blood vessel, nerve fiber and so on. When the dielectric properties of these tissues are measured by conventional sensor, the results are not the dielectric properties of tissues but the effective dielectric properties of the mixture. In this paper, the influence of the inclusion in tissues on the measurement of dielectric properties of heterogeneous biological tissues is studied and the analysis of the effective dielectric properties of heterogeneous tissues based on the mixing rule is proposed. When the coaxial probe is used to measure the dielectric properties of tissue, the results are relative to the dielectric properties of inclusion, dielectric properties of background tissue and the effective volume fraction of inclusion. Therefore, the dielectric properties of inclusion could be calculated according to mixing rule, after the effective dielectric properties are measured and the effective volume fraction of inclusion is estimated.

A non-invasive blood glucose measurement sensor and the data process algorithm based on the metabolic energy conservation (MEC) method are presented in this paper. The physiological parameters of human fingertip can be measured by various sensing modalities, and blood glucose value can be evaluated with the physiological parameters by the multiple linear regression analysis. Five methods such as enter, remove, forward, backward and stepwise in multiple linear regression were compared, and the backward method had the best performance. The best correlation coefficient was 0.876 with the standard error of the estimate 0.534, and the significance was 0.012 (sig. <0.05), which indicated the regression equation was valid. The Clarke error grid analysis was performed to compare the MEC method with the hexokinase method, using 200 data points. The correlation coefficient R was 0.867 and all of the points were located in Zone A and Zone B, which shows the MEC method provides a feasible and valid way for non-invasive blood glucose measurement.

Mean scatterer spacing (MSS) estimated from ultrasonic backscattering is of valuable information for tissue characterization. However, low ultrasound frequency, sound attenuation, and diffuse scattering significantly disturb the current MSS measurement methods. The aim of this study is to improve MSS measurement with Coded Excitation (CE) enhanced cepstrum estimation. The study proposes a Golay code-based cepstrum estimation and uses an equivalent Faran cylinder model of cancellous bone. By solving the elastic wave equation, ultrasonic backscattering signals were obtained through simulations. The adopted ultrasonic excitation is 0.9 MHz and is coded with 4-bit complementary sequences, which is modulated by employing a sinusoidal signal. Also, white Gaussian noise of 60 dB, 55 dB, and 45 dB was added to the backscattering data to study the robustness of the proposed method. Simulation results show that the Golay-based method successfully improved ultrasound energy transmission into the tissue and effectively suppressed interference peaks while identifying the right peaks with permitted errors. In addition, the robustness against noise was enhanced.

Intracoronary ultrasound (ICUS) is a widely used interventional imaging modality in clinical diagnosis and treatment of cardiac vessel diseases. Due to cyclic cardiac motion and pulsatile blood flow within the lumen, there exist changes of coronary arterial dimensions and relative motion between the imaging catheter and the lumen during continuous pullback of the catheter. The action subsequently causes cyclic changes to the image intensity of the acquired image sequence. Information on cardiac phases is implied in a non-gated ICUS image sequence. A 1-D phase signal reflecting cardiac cycles was extracted according to cyclical changes in local gray-levels in ICUS images. The local extrema of the signal were then detected to retrieve cardiac phases and to retrospectively gate the image sequence. Results of clinically acquired in vivo image data showed that the average inter-frame dissimilarity of lower than 0.1 was achievable with our technique. In terms of computational efficiency and complexity, the proposed method was shown to be competitive when compared with the current methods. The average frame processing time was lower than 30 ms. We effectively reduced the effect of image noises, useless textures, and non-vessel region on the phase signal detection by discarding signal components caused by non-cardiac factors.

Optimal graft design has been an objective of many researchers to find correlations between hemodynamics and graft failure. Compared to planar grafts, the helical graft configurations improve hemodynamic performance including the promotion of flow mixing and reduction of flow stagnation regions. In order to evaluate the advantages and disadvantages of the suggested helical type bypass graft model in comparison to a conventional bypass graft configuration, three experimental models were designed and evaluated. The character of complex vortex structures created in the area between the heel and the occluded section depends on the flow parameters (in the case of the straight graft). We have identified two vortices in the symmetrical plane (proximal and distal to the anastomosis). In the new design of the two-turn helical graft, the stagnation point is eliminated from the anastomoses at different time intervals compared to the conventional straight bypass model The present study indicated that the magnitude of the pressure drop along a helical graft was considerably increased compared to a traditional graft which, while still physiologically advantageous, can be surpassed by an optimal geometry model.

Previous literatures have indicated that hypothalamic paraventricular nucleus (PVN) neurons are important for regulating the level of sympathetic and vagal nervous activity. Sympathovagal balance is closely related to heart rate variability (HRV). However, it still requires further elucidation regarding the effect of PVN on HRV by regulating sympathovagal balance. To detect the influence of the PVN on HRV, we evaluated the changes in time domain (including standard deviation of the R-R intervals (SDNN), and the root mean square of successive differences (RMSSD)) and frequency domain (including low frequency (LFnu), high frequency (HFnu) and the ratio of LF/HF) in HRV upon appropriate electronic stimulation, and lesions on the PVN of the rat in vivo. Cardiac vagal modulation was evaluated by HFnu; sympathetic modulation was evaluated by LFnu. Sympathovagal balance was evaluated by LF/HF and SDNN. Upon electronic stimulating (less than 0.6 mA) to the PVN of rats, we found that LFnu and HFnu changed correspondingly but recovered after the stimulation. When the PVN of the rats was injured, the RR intervals were enhanced with the rats’ unilaterally or bilaterally injured PVN, especially the bilateral lesion. Meanwhile, LFnu, LF/HF and SDNN decreased gradually, accompanied with an increase of HFnu levels. So these PVN changes may indicate alterations of the sympathovagal balance.

The effects of gender and other contributory factors on pulse waveform are still under arguments. In view of different results caused by few considerations of possible influential factors and general agreement of gender relating to pulse waveform, this study aims to address the confounding factors interfering with the association between gender and pulse waveform characteristics. A novel method was proposed to noninvasively detect pressure pulse wave and assess the morphology of pulse wave. Forty healthy young subjects were included in the present research. Height, weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured manually and body mass index (BMI), pulse blood pressure (PP) and heart rate (HR) were calculated automatically. Student’s t test was used to analyze the gender difference and analysis of variance (ANOVA) to examine the effects of intrinsic factors. Univariate regression analysis was performed to assess the main factors on the waveform characteristics. Waveform features were found significantly different between genders. However this study indicates that the main factors for time-related and amplitude-related parameters are HR and SBP respectively. In conclusion, the impact of HR and SBP on pulse waveform features should not be underestimated, especially when analyzing the gender difference.

Transparent tooth correction treatment is an esthetic alternative to traditional orthodontic treatment. Recently, attachments were introduced in transparent tooth correction treatments to improve the predictability of orthodontic movement. In order to optimize the attachment configuration, the force delivery system of attachments in orthodontic aligner treatment was analyzed. Based on mechanical principles, such as the synthesis theorem of force system, Varignon theorem, and the theorem of force translation, the force system of attachment was analyzed. How the attachments affected the orthodontic treatment was investigated. The attachments’ force system F r , F t , M r and M t was determined. The optimum attachment for translation and controlled tipping movement was conceived. The attachments can be designed and placed appropriately to improve tooth movement.

To investigate the stress distribution of a severely damaged maxillary anterior tooth restored with a computer-aided design/computer-aided manufacturing (CAD/CAM) glass-fiber post system. Twelve models were fabricated with different alveolar bone levels and cervical dentin wall thicknesses and studied using a two-dimensional finite element method. A force of 100 N was applied to the lingual surface of the crown at 45 degrees, and the maximum von Mises stress was calculated. A higher stress level was observed in the dentin than in the post and crown. With the reduction of dentin thickness, the maximum von Mises stress in the dentin increased slightly to a peak at a thickness of 1.5 mm, followed by a slight decrease at a thickness of 1.0 mm. However, the relative ratio (RR) values did not show a large difference (RR > 80%). Meanwhile, a large difference in RR values was observed with a change in bone level (RR < 80%). When using a CAD/CAM glass-fiber post system, the maximal von Mises stress was significantly affected by the bone level, rather than by the dentin thickness. Moreover, this system may be applied to the treatment of a maxillary anterior tooth with a bone level of only 2/3.

To simulate pulse wave propagation, we set up a wave propagation model using blood-wall interaction in previous work. In this paper, our purpose is to investigate wall stress and deformation of the wave propagation model. The finite element method is employed for solving the governing equations of blood and wall. Our results suggest that there are two peaks in the circumferential stress and strain distributions of the normal model. The stress and strain values change with the varieties of different factors, such as wall thickness and vessel diameter. The results indicate that different parameters of fluid and tube wall have remarked impact on wall stress and deformation.

This paper introduces the application of uniform experimental design to improve dental implant systems subjected to dynamic loads. The dynamic micromotion of the Zimmer dental implant system is calculated and illustrated by explicit dynamic finite element analysis. Endogenous and exogenous factors influence the success rate of dental implant systems. Endogenous factors include: bone density, cortical bone thickness and osseointegration. Exogenous factors include: thread pitch, thread depth, diameter of implant neck and body size. A dental implant system with a crest module was selected to simulate micromotion distribution and stress behavior under dynamic loads using conventional and proposed methods. Finally, the design which caused minimum micromotion was chosen as the optimal design model. The micromotion of the improved model is 36.42 μm, with an improvement is 15.34% as compared to the original model.

The purpose of this study is to compare the stress of the bone around the mini-implant under the two kinds of force: the composite force which contains torque and traditional single force. There were 96 finite element models formed by the combination of mini-implant and bone, with diameters of 1.2 mm, 1.6 mm, 2.0 mm and corresponding length being 6 mm, 8 mm, 10 mm, 12 mm, respectively. Each size corresponded to 8 models. Group SF (each size n=4) was loaded with 200 g single force, while Group CF (each size n=4) was loaded with composite force which contained 6N mm torque and 200 g single force. The maximum equivalent stress (Max EQS) of the bone surrounding mini implant with different loading directions was calculated, and the relationship of force direction, diameter and length was also evaluated. The Max EQS of Group CF was higher than that of Group SF. The effect of force direction on the stress was related to the diameter of mini implant, but had nothing to do with its length. The Max EQS of the cortical bone around mini implant in Group CF was higher (P<0.05) than that in Group SF. In contrast, there was no significant difference (P>0.05) between Group SF and Group CF in terms of bone stress when the diameter of mini implant was 1.6 mm or 2.0 mm. In our study, it is demonstrated that the diameter of mini-implant is better to be larger than 1.2 mm when a mini-implant is used in a torque control of tooth. The impact of this feature in the clinical setting needs to be verified.

A kind of Ti-Ni shape memory alloy (SMA) hysteretic nonlinear model is developed, and the loss mechanism of a SMA tracheal stent subjected to cough excitation is studied in this paper. Nonlinear differential items are introduced to express the hysteretic phenomena of Ti-Ni SMA, and the fitting effect of the SMA constitutive model on the experimental data is proved by the partial least-square regression method. The nonlinear dynamic model of a Ti-Ni SMA tracheal stent subjected to cough excitation is developed, and the system’s dynamic response is obtained. The numerical results show that the system’s vibration is little in weak excitation, becomes large with the increase of the stochastic excitation, and finally becomes little again with the further increase of the stochastic excitation; the stochastic resonance phenomenon occurs in the process, which may cause stent fracture or loss.

The main aim of this article was to introduce the application of a uniform design for experimental methods to drop the micromotion of a novel ITI dental implant model under the dynamic loads. Combining the characteristics of the traditional ITI and Nano-Tite implants, a new implant with concave holes has been constructed. Compared to the traditional ITI dental implant model, the micromotion of the new dental implant model was significantly reduced by explicit dynamic finite element analysis. From uniform design of experiments, the dynamic finite element analysis method was applied to caluculated the maximum micromotion of the full model. Finally, the chief design in all the experiment simulations which cause the minimum micromotion is picked as the advanced model of the design. Related to the original design, which was associated with a micromotion of 45.11 μm, the micromotion of the improved version was 31.37 μm, for an improvement rate of 30.5%.

A driver’s response to a front-coming vehicle collision consists of braking reaction time and braking behavior. The purpose was to investigate drivers’ responses at different speeds, relative distances, and particularly the behavior on the accelerator at the collision moment. Twelve young men participated in driving simulator tests. Vehicle parameters and electromyograms (EMGs) of the drivers’ tibialis anterior muscles were recorded and responses were analyzed. The drivers’ braking reaction time windows were divided into pre-motor time, muscle activation time, accelerator release time, and movement time. By comparing the reaction times and collision times, braking behaviors were investigated. It was found that movement times (r = -0.281) decreased with speed. Pre-motor times (r = 0.326) and muscle activation times (r = 0.281) increased with relative distance. At the collision moment, the probability of the driver’s lower extremity being on the accelerator, in the air, and on the brake pedal was 7.4%, 18.9%, and 73.7%, respectively. With higher speeds and smaller distances, the lower extremity was more likely to be in the air or even on the accelerator in different muscle activation states. The driver will collide in normal driving postures which muscles are not or not fully activated in very urgent situation.

Applications of neural machine interfaces have received increased attention during the last decades. It is crucial to realize the continuous control of prosthetic devices based on biological signals. In order to deal with the highly nonlinear relationship between the Electromyography (EMG) signals and motion, this study presents a novel decoding approach which employs multi-output support vector regression (M-SVR). The proposed M-SVR is compared with other popular regression techniques and the experimental results demonstrate the effectiveness of M-SVR in hand continuous movement trajectory reconstruction.

This study investigated the feasibility of the Infrared (IR) sensor-based walking aids for detecting the gait intention. To compensate for the defects of Force Sensing Resistors (FSRs) or force sensors, such as the velocity control problem on gait slopes, we used IR sensors to investigate knee joint anterior displacement in order to recognize the gait intention. We also measure leg muscle activities and foot pressure, in order to verify our investigation. We placed two IR sensors on the rollator center to sense left and right leg walking intentions. We took EMG signals of four leg muscles, and analyzed them. Foot pressure analysis parameters were the measured force and mean pressure. We conducted experiments on twenty young healthy adults. The results show that knee joint anterior displacement increases according to gait slope and velocity. We confirm similar results of knee joint anterior displacement through the IR sensors.

Tremor usually occurs in a patient’s upper limb with a roughly sinusoidal profile. Understanding the inner mechanism of the involuntary movement is fundamental to improving tremor suppression treatments. Therefore, the musculoskeletal model of the elbow joint was developed in this study. Initially, healthy subjects were selected to simulate tremor and the tremulous data was collected with the purpose of sparing patients from fatigue. With the recorded joint angle and surface EMG (sEMG), the model was calibrated to subjects by optimization approach. The activation derived from the electric pulse was employed to drive the tuned model and the model’s output was compared with the angle predicted by the EMG-driven musculoskeletal model. The results demonstrated that the performance of the calibrated model was improved by a smaller normalized root mean square error and a higher coefficient of determination compared with the no-tuned model. There was no significant difference between the angles estimated by the tuned model activated by the electric pulse and muscle excitation. It indicates that neural activation could be replaced by the electric pulse to excite the limbs for desired angle. Therefore, the study presents a good way to evaluate the feasibility of Functional Electric Stimulation to suppress tremor.

The effects of pelvic asymmetry and idiopathic scoliosis on postural balance during sitting were studied by measuring inclination angles, pressure distribution, and electromyography. Participants were classified into a control group, pelvic asymmetry group, scoliosis group, and scoliosis with pelvic asymmetry and then performed anterior, posterior, left, and right pelvic tilting while sitting on the unstable board for 5 seconds to assess their postural balance. Inclination and obliquity angles between the groups were measured by an accelerometer located on the unstable board. Pressure distribution (maximum force and peak pressure) was analyzed using a capacitive seat sensor. In addition, surface electrodes were attached to the abdominal and erector spinae muscles of each participant. Inclination and obliquity angles increased more asymmetrically in participants with both pelvic asymmetry and scoliosis than with pelvic asymmetry or scoliosis alone. Maximum forces and peak pressures of each group showed an asymmetrical pressure distribution caused by the difference in height between the left and right pelvis and curve type of the patients’ spines when performing anterior, posterior, left, and right pelvic tilting while sitting. Muscle contraction patterns of external oblique, thoracic erector spinae, lumbar erector spinae, and lumbar multifidus muscles may be influenced by spine curve type and region of idiopathic scoliosis. Asymmetrical muscle activities were observed on the convex side of scoliotic patients and these muscle activity patterns were changed by the pelvic asymmetry. From these results, it was confirmed that pelvic asymmetry and idiopathic scoliosis cause postural asymmetry, unequal weight distribution, and muscular imbalance during sitting.

This study designs and fabricates a novel integrated digital hand grip dynamometer and analyzes collected grip strength data. The dynamometer directly stores collected data in a computer, unlike those on the market that cannot directly store information. A strain gauge load cell is used as a force sensor. The dynamometer is designed to maximize ergonomics. Excitation voltage of the load cell is 5 V, and a 9 V battery supplies power to its circuit. The signal receiver is National Instruments (NI) data acquisition (DAQ) card that transmits signals to the computer. The operation system is designed using LabView. This study assesses the correlation between variables of collected data. The correlation coefficients for height, weight and palm length were 0.793, 0.609 and 0.715, respectively, indicating that variables were moderately to strongly correlate with grip strength.

Frontal vehicle collisions can cause injury to a driver’s cervical muscles resulting from intense changes in muscle strain and muscle load. This study investigated the influence of collision forces in a sled test environment using a modified Hybrid III 50^th percentile dummy equipped with simulated spring-type muscles. Cervical muscle responses including strain and load of the sternocleidomastoid (SCM), splenius capitis (SPL), and trapezius (TRP) were analyzed, and muscle injury was assessed. The SCM, SPL, and TRP suffered average peak muscle strains of 21%, 40%, and 23%, respectively, exceeding the injury threshold. The average peak muscle loads of the SCM, SPL and TRP were 11 N, 25 N, and 25 N, respectively, lower than the ultimate failure load. The SPL endured the largest injury, while the injuries to the SCM and TRP were relatively small. This is a preliminary study to assess the cervical muscle of driver during a frontal vehicle collision. This study provides a foundation for investigating the muscle response and injury in sled test environments, which can lead to the improvement of occupant protections.

To investigate the stress distribution in a maxillary canine restored with each of four different post systems at different levels of alveolar bone loss. Two-dimensional finite element analysis (FEA) was performed by modeling a severely damaged canine with four different post systems: CAD/CAM zirconia, CAD/CAM glass fiber, cast titanium, and cast gold. A force of 100 N was applied to the crown, and the von Mises stresses were obtained. FEA revealed that the CAD/CAM zirconia post system produced the lowest maximum von Mises stress in the dentin layer at 115.8 MPa, while the CAD/CAM glass fiber post produced the highest stress in the dentin at 518.2 MPa. For a severely damaged anterior tooth, a zirconia post system is the best choice while a cast gold post ranks second. The CAD/CAM glass fiber post is least recommended in terms of stress level in the dentin.

To compare the biomechanical characters of three-level anterior cervical fusion and hybrid constructs by measuring coupled motion changes of the cervical spine, Eighteen adult human cadaveric cervical spines were biomechanically investigated under eccentric displacement control in lateral bending and axial rotation by measuring vertebral motion (X, Y, Z -axis).The 3DPD condition displayed similar coupled motion compared to the intact condition both in lateral bending and in axial rotation, while the 3PDP condition was similar only in lateral bending. However, the coupled motion of the cervical spine under 3P conditions markedly changed in both lateral bending and axial rotation. Considering the coupled motion characteristics, the 3DPD hybrid construct is biomechanically advantageous in three types of reconstructions (3DPD, 3PDP, 3P).

Muscular rigidity and atrophy caused by long-term underactivity usually lead to foot drop, strephenopodia, foot extorsion or some other complications for the lower limb movement disorders or lower limb surgery sufferers. The ankle-foot orthosis can help patients conduct the right ankle motion mode training, inhibit spasm and prevent ankle complications. In this paper, a quasi-passive 3 DOFs ankle-foot wearable orthosis was designed on the basis of kinematics and dynamics analysis of the ankle joint. Ankle joint trajectory and dynamic characteristics similar to those of natural gait can be obtained by the combination of passive energy storage and additional power complement. In terms of function, the orthosis has shock absorption and low energy consumption. Given its excellent characteristics of comfortableness, lightweight, and anthropomorphic construction, the orthosis can be used in medical institutions for rehabilitation training or as a daily-walking auxiliary equipment for surgery sufferers.

Robot-assisted rehabilitation has been developed and proved effective for motion function recovery. Humanization is one of the crucial issues in the designing of robot-based rehabilitation system. However, most of the previous investigations focus on the simplex position control when comes to the control system design of robot-assisted passive training, and pay little attention to the dynamic adjustment according to the patient’s performances. This paper presents a novel method to design the passive training system using a developed assessing-and-regulating section to online assess the subject’s performances. The motion regulating mechanism is designed to dynamically adjust the training range and motion speed according to the actual performances, which is helpful to improve the humanization of the rehabilitation training. Moreover, position-based impedance control is adopted to achieve compliant trajectory tracking movement. Experimental results demonstrate that the proposed method presents good performances not only in motion control but also in humanization.

Aiming at the hand rehabilitation of stroke patients, a wearable hand exoskeleton with circuitous joint is proposed. The circuitous joint adopts the symmetric pinion and rack mechanism (SPRM) with the parallel mechanism. The exoskeleton finger is a serial mechanism composed of three closed-chain SPRM joints in series. The kinematic equations of the open chain of the finger and the closed chains of the SPRM joints were built to analyze the kinematics of the hand rehabilitation exoskeleton. The experimental setup of the hand rehabilitation exoskeleton was built and the continuous passive motion (CPM) rehabilitation experiment and the test of human-robot interaction force measurement were conducted. Experiment results show that the mechanical design of the hand rehabilitation robot is reasonable and that the kinematic analysis is correct, thus the exoskeleton can be used for the hand rehabilitation of stroke patients.

This study shows the improvement of muscle activity and muscle strength imbalance in the lower extremities through independent exercise loads in vibration platform. Twenty females of age 20 participated in this study. The subjects were divided into WBV group, with more than 10% of muscle strength imbalance between left and right the lower extremities, and control group, with less than 10% of muscle strength imbalance between left and right the lower extremities. As the prior experiment showed, different exercise postures provide different muscular activities. As a result, the highest muscular activity was found to be in the low squat posture. Therefore, the LS posture was selected for the exercise in this experiment. Vibration intensities were applied to dominant muscle and non-dominant muscle, and the vibration frequency was fixed at 25Hz for the WBV group. The control group was asked to perform the same exercise as the WBV group, without stimulated vibration. This exercise was conducted for a total of 4 weeks. As a result, the WBV group which showed an average deviation of 16% before the experiment, tended to decrease approximately to 5%. In this study, vibration exercise using load deviation is shown to be effective in improving the muscle strength imbalance.

Marker placement can be a significant source of error in biomechanical studies of human movement. The toe marker placement error is amplified by footwear since the toe marker placement on the shoe only relies on an approximation of underlying anatomical landmarks. Three total knee replacement subjects were recruited and three self-speed gait trials per subject were collected. The height variation between toe and heel markers of four types of footwear was evaluated from the results of joint kinematics and muscle forces using OpenSim. The reference condition was considered as the same vertical height of toe and heel markers. The results showed that the residual variances for joint kinematics had an approximately linear relationship with toe marker placement error for lower limb joints. Ankle dorsiflexion/plantarflexion is most sensitive to toe marker placement error. The influence of toe marker placement error is generally larger for hip flexion/extension and rotation than hip abduction/adduction and knee flexion/extension. The muscle forces responded to the residual variance of joint kinematics to various degrees based on the muscle function for specific joint kinematics. This study demonstrates the importance of evaluating marker error for joint kinematics and muscle forces when explaining relative clinical gait analysis and treatment intervention.

The present study evaluated effects of exercise training on the proprioception sensitivity, postural stability, and the likelihood of slip-induced falls. Eighteen older adults (6 in balance, 6 in weight, and 6 in control groups) participated in this study. Three groups met three times per week over the course of eight weeks. Ankle and knee proprioception sensitivities and postural stability were measured. Slip-induced events were introduced for all participants before and after training. The results indicated that, overall, strength and postural stability were improved only in the training group, although proprioception sensitivity was improved in all groups. Training for older adults resulted in decreased likelihood of slip-induced falls. The study suggested that proprioception can be improved by simply being active, however, the results suggested that training would aid older adults in reducing the likelihood of slip-induced falls.

From a subject group of pes cavus, the purpose of this study was to evaluate the biomechanical characteristics of lower limbs, based on plantar foot pressure and electromyography (EMG) activities, by the effects on two kind of custom-made insoles. Ten individuals among thirty females with a clinical diagnosis of idiopathic pes cavus (mean age (SD): 22.3 (0.08) years) were selected for the study. The plantar foot pressure data and EMG activities of four lower limb muscles were collected, when subjects walked on a treadmill, under three different experimental conditions. The plantar foot pressure data was analyzed, after the bilateral foot was divided into three areas of masks and into four sections of stance phase, to compare plantar foot pressure. The EMG activities were analyzed for integrated EMG (IEMG) value. The results show that plantar foot pressure concentrated in particular parts is decreased by custom-made insoles. In the case of EMG, all the muscle activities decreased significantly. The custom-made insoles dispersed pressure concentrated by the higher medial longitudinal arch and improved the efficient use of muscles. In particular, the extension structure in the forefoot of custom-made insoles was more efficient for pes cavus. Therefore, it could help patients to walk, by offering support to prevent the disease of pes cavus deformity, and to relieve the burden and fatigue in the lower limbs on gait.

This study analyzes the moment of human main joints (knee and hip) for developing a wearable walking assistant robot. Experiments were performed on two steps to analyze motions. Three healthy males with no neural and musculoskeletal disorders volunteered to participate in this study. In the step up test, the maximum moment was 0.98±0.05 Nm/kg for the knee and 0.52±0.04 Nm/kg for the hip. In the sit-to-stand test, the maximum moment was 0.88±0.06 Nm/kg for the knee and 0.44±0.04 Nm/kg for the hip. The moment of the hip was significantly higher than the knee. In addition, the motion analysis results were compared with proven validity and inverse dynamics analysis results. Experimental results showed that there was no significant difference in the absolute value or pattern. For the step up motion, after wearing Powered Gait Orthosis (PGO), the hip joint torque value (1.22 Nm/kg) was about 1.3 times greater than the knee joint torque value (0.96 Nm/kg). It indicates that the step up motion requires more power from the hip joint than the knee joint. Moreover, there was a significant torque value difference for before and after wearing the device.

This paper introduces novel modern equipment—a lower extremity exoskeleton, which can implement the mutual complement and the interaction between human intelligence and the robot’s mechanical strength. In order to provide a reference for the exoskeleton structure and the drive unit, the human biomechanics were modeled and analyzed by LifeModeler and Adams software to derive each joint kinematic parameter. The control was designed to implement the zero-force interaction between human and exoskeleton. Furthermore, simulations were performed to verify the control and assist effect. In conclusion, the system scheme of lower extremity exoskeleton is demonstrated to be feasible.

Sino-atrial node cells (SANCs) play a significant role in rhythmic firing. To investigate their role in arrhythmia and interactions with the atrium, computer simulations based on cellular dynamic mathematical models are generally used. However, the large-scale computation usually makes research difficult, given the limited computational power of Central Processing Units (CPUs). In this paper, an accelerating approach with Graphic Processing Units (GPUs) is proposed in a simulation consisting of the SAN tissue and the adjoining atrium. By using the operator splitting method, the computational task was made parallel. Three parallelization strategies were then put forward. The strategy with the shortest running time was further optimized by considering block size, data transfer and partition. The results showed that for a simulation with 500 SANCs and 30 atrial cells, the execution time taken by the non-optimized program decreased 62% with respect to a serial program running on CPU. The execution time decreased by 80% after the program was optimized. The larger the tissue was, the more significant the acceleration became. The results demonstrated the effectiveness of the proposed GPU-accelerating methods and their promising applications in more complicated biological simulations.

To evaluate the fidelity of the iDental system and investigate its utility and performance on simulated drilling operations, user studies consisting of objective and subjective evaluations were performed. A voxel-based drilling simulation sub-system in the iDental system was employed for evaluation. Twenty participants were enrolled to take part in the experiments and were divided into two groups: novice and resident. A combined evaluation method including objective and subjective methods was employed. The objective evaluation included two dental drilling tasks: caries removal operation and pulp chamber opening operation. In the subjective method, participants were required to complete a questionnaire to evaluate the fidelity of the system after the operation task. Based on the structured global assessment scales in the questionnaire, the average subjective evaluation scores of the proposed metrics were greater than 4.5, demonstrating that the system operated above medium fidelity. Dentists expressed great interest and positive attitudes toward the potential of the iDental system. The objective evaluation data including time spent and the volume of removed healthy and carious tissue were obtained. Although no significant differences could be found between the two groups, the volume of removed caries and the depth of pulp chamber insertion manifested small standard deviations. Evaluation results illustrated that dentists were willing to use the virtual reality training system. Several future research topics were identified, including increasing the task difficulty, improving the system fidelity and introducing appropriate finger rest points.

High compliant legs are essential for the efficient versatile locomotion and shock absorbency of humans. This study proposes a biped robot actuated by pneumatic artificial muscles to mimic human locomotion. On the basis of the musculoskeletal architecture of human lower limbs, each leg of the biped robot is modeled as a system of three segments, namely, hip joint, knee joint, and ankle joint, and eleven muscles, including both monoarticular and biarticular muscles. Each rotational joint is driven by a pair of antagonistic muscles, enabling joint compliance to be tuned by operating the pressure inside the muscles. Biarticular muscles play an important role in transferring power between joints. Walking simulations verify that biarticular muscles contribute to joint compliance and can absorb impact energy when the robot makes an impact upon ground contact.

Auditory temporal integration (ATI) has been widely described in psychoacoustic studies, especially for loudness perception. Loudness increases with increasing sound duration for durations up to a time constant about 100 ∼ 200 ms, and then loudness becomes saturated with more duration increase. However, the electrophysiological mechanism underlying the ATI phenomenon has not been well understood. To investigate ATI at the brainstem level of auditory system and its relationship to cortical and behavioral ATI, frequency follow response (FFR) was acquired in our study. Simultaneously, ATI in auditory cortex was evaluated by cortical response P1. Behavioral loudness and electrophysiological measures were estimated from normal-hearing young adults for vowel /a/ whose durations varied from 50 ms to 175 ms. Significant effects of stimulus duration were found both on FFR and P1 amplitudes. Linear regression analysis revealed that as stimulus duration increased, brainstem FFR amplitude was significantly associated with cortical P1 amplitude and behavioral loudness, which confirmed the existence of temporal integration in auditory brainstem. Moreover, behavioral loudness ATI was better predicted using brainstem and cortical measures together than merely using each one separately, indicating an interplay and coordination for ATI across the three levels along auditory pathway.

Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

Snoring, a common symptom in the general population may indicate the presence of obstructive sleep apnea (OSA). In order to detect snoring events in sleep sound recordings, a novel method was proposed in this paper. The proposed method operates by analyzing the acoustic characteristics of the snoring sounds. Based on these acoustic properties, the feature vectors are obtained using the mean and standard deviation of the sub-band spectral energy. A support vector machine is then applied to perform the frame-based classification procedure. This method was demonstrated experimentally to be effective for snoring detection. The database for detection included full-night audio recordings from four individuals who acknowledged having snoring habits. The performance of the proposed method was evaluated by classifying different events (snoring, breathing and silence) from the sleep sound recordings and comparing the classification against ground truth. The proposed algorithm was able to achieve an accuracy of 99.61% for detecting snoring events, 99.16% for breathing, and 99.55% for silence.

During the rehabilitation process, it is essential to accurately judge a patient’s recovery in a timely manner. A reasonable and matched training program is significant in the development of rehabilitation system. This paper presents a new upper limb rehabilitation training system, which consists of an upper limb rehabilitation training device, a current detection circuit, a motor speed test circuit, a surface EMG (sEMG) sensor, and a dSPACE HIL simulation platform. The real-time output torque of the servo motor is calculated by using the motor’s real-time current and speed, in order to monitor the patient’s training situation. The signal of sEMG is collected in real time and is processed with root mean square (RMS) to characterize the degree of muscle activation. Based on this rehabilitation system, maximum voluntary contraction (MVC) experiments, passive training experiments under different speeds, and active training experiments under different damping are studied. The results show that this new system performs real-time and accurate monitoring of a patient’s training situation. It can also assess a patient’s recovery through muscle activation. To a certain extent, this system provides a platform for research and development of rehabilitation medical engineering.

Essential tremor is an involuntary trembling of body limbs in people without tremor-related disease. In previous study, suppression of tremor by sensory electrical stimulation was confirmed on the index finger. This study investigates the effect of sensory stimulation on multiple segments and joints of the upper limb. It denotes the observation regarding the effect’s continuity after halting the stimulation. 18 patients with essential tremor (8 men and 10 women) participated in this study. The task, “arms stretched forward”, was performed and sensory electrical stimulation was applied on four muscles of the upper limb (Flexor Carpi Radialis, Extensor Carpi Radialis, Biceps Brachii, and Triceps Brachii) for 15 seconds. Three 3-D gyro sensors were used to measure the angular velocities of segments (finger, hand, and forearm) and joints (metacarpophalangeal and wrist joints) for three phases of pre-stimulation (Pre), during-stimulation (On), and 5 minute post-stimulation (P5). Three characteristic variables of root-mean-squared angular velocity, peak power, and peak power frequency were derived from the vector sum of the sensor signals. At On phase, RMS velocity was reduced from Pre in all segments and joints while peak power was reduced from Pre in all segments and joints except for forearm segment. Sensory stimulation showed no effect on peak power frequency. All variables at P5 were similar to those at On at all segments and joints. The decrease of peak power of the index finger was noted by 90% during stimulation from that of On phase, which was maintained even after 5 min. The results indicate that sensory stimulation may be an effective clinical method to treat the essential tremor.

This paper studies and assesses how rehabilitation activities and supervised computer games incorporated into a system aimed at people diagnosed with Autism Spectrum Disorder (ASD) can be used to work on the areas affected by ASD at any time and in any place. This research specifically assesses the areas that affect communication and interaction between people with ASD and professionals. In order to do this, a group of 20 children diagnosed with ASD of between 3 and 8 years old (clinical group) was used, together with a group of 20 children of between 3 and 8 years old with a neurotypical development, which served as a control group. During the tests, response time and visual interaction with the session leader were evaluated. Despite the fact that the clinical group spent more time (M = 21.08 sec) than the control group (M = 4.52) to interact leader, eye contact predominated in the interaction. As a result of the pilot study, the system obtained could help in cognitive rehabilitation.

To evaluate the ability of assessing the refractive change induced by myopic laser surgery using the intrinsic data, obtained from a reference intrinsic to the cornea. Twenty-nine eyes with laser in situ keratomileusis for myopia were included in the study. Statistical analyses were performed to determine the relationship between refractive changes and two kinds of corneal power: KIP_value (obtained by keratometric index of 1.3375 and radius of curvature) and RIP_value (obtained by real corneal refraction index of 1.376 and radius of curvature). The comparisons were made between results given by intrinsic data and Pentacam HR. Preoperatively, the intrinsic radii of curvature are significantly less (p≪0.001) than those from Pentacam HR, while the intrinsic radii of curvature are significantly larger (p≪0.001) after surgery. The corneal power changes given by Pentacam HR always underestimate the refractive changes. However, the intrinsic data generally reduce the discrepancies between the corneal power and the refractive changes. The intrinsic KIP_value correlated best with the refractive changes at the corneal plane (p≪0.001) with a prediction error as low as 1.51%. The use of intrinsic data of the cornea can possibly provide an accurate estimation of surgically induced refractive changes.

The change of neuronal activation due to the passive perception of various driving speeds in comparison to a reference driving speed was assessed using functional Magnetic Resonance Imaging. Videos recorded in real driving conditions on the road at driving speeds of 50, 70, 90, and 110 km/h were shown as visual stimuli. An experiment consisted of three blocks, each having a control phase (50km/h) and a stimulation phase (70, 90, or 110 km/h). In the passive perception of various driving speed differences, the areas related to visual cognition and spatial attention such as temporal, occipital, parietal, frontal areas, and cerebellum were activated. As the driving speed difference increased, the number of activated voxels also increased in the areas related to visual cognition. However, the visual cognition related areas showed a different pattern from the spatial attention related area with an increase of the driving speed difference. This implies that each brain area has a different level of involvement in the passive perception of the driving speed difference, although both visual cognitions related areas and spatial attention related area are related to it.

In this study, it was investigated whether a NO signaling pathway is involved in the anti-epileptic effect of curcumin on pentylenetetrazol (PTZ)-kindled rats. PTZ-kindled rats received different doses of curcumin that were administered intraperitoneally for 24 days. Either a non-selective inhibitor of nitric oxide synthase (NOS) (N-nitro-L-arginine methyl ester (L-NAME)), a selective inhibitor of neuronal NOS (7-Nitroindazole (7-NI)), a selective inhibitor of inducible NOS (aminoguanidine (AG)), or a NO precursor (L-arginine (L-ARG)) was administered chronically to evaluate the role of NO in curcumin’s anti-seizure effect. A chronic administration of curcumin (200 mg/kg) was most effective for decreasing the mean frequency of epileptiform discharge. Furthermore, a pretreatment with L-NAME or 7-NI augmented the anti-epileptic effect of curcumin. In contrast, AG failed to significantly alter the anti-epileptic effect of curcumin. A pretreatment with L-ARG temporally reversed the anti-epileptic effect of curcumin in the early stage, but in the late stage, it potentiated curcumin’s anti-epileptic effect. These findings suggest that the L-arginine–nitric oxide pathway may be involved in the anti-epileptic properties of curcumin, and that the role of nNOS (and not iNOS) is prominent in this neuroprotective feature.

In this study, the contrast-induced-nephropathy (CIN) of vascular patients who had undergone angiography was quantitatively evaluated using a semi-empirical model. The model compiled six essential serum readings and biological data from 70 patients in order to develop a 1st-order nonlinear equation with 16 defined terms. The expectation value of the model was used to predict the serum creatinine reading of patients that had been determined to be at high risk of CIN after contrast media (CM) administration. The other five variables included body surface area (BSA), administrated CM, serum creatinine level before CM administration, blood urea nitrogen (BUN), and systolic blood pressure level. A loss function was used to define the difference between the observed and predicted serum creatinine readings after CM administration. The dominant variables were proven to be systolic blood pressure, serum creatinine level before CM administration, and BSA. The cross interaction between the serum creatinine level before CM administration and systolic blood pressure was the decisive term of the model’s performance, indicating that both should be specially considered in order to prevent CIN. The BSA, which was usually ignored by medical staff, was also proven to be a significant variable, whereas the BUN reading and amount of injected contrast media were negligible in the semi-empirical model.

Correct-active-repetitive exercise is important for the motor recovery in hemiplegics. The present study hypothesizes that the electromyogram (EMG)-controlled assistance of motion would be an effective implementation of the concept for the rehabilitation of the hemiplegic shoulder, even in chronic patients. This study aims to investigate the feasibility of the suggested method. The motor intention is derived from the EMG of the shoulder muscles and the shoulder movement (flexion and abduction) is assisted by an electro-mechanical system only when the motor intention (EMG amplitude) exceeded the threshold. Twelve patients in the chronic stage of stroke participated in this pilot study. The EMG-controlled assistive exercise lasts for two weeks, 20 min per day and 5 days a week. The active range of motion in both abduction and flexion increases significantly after the intervention (p < 0.01). The maximum torque increases in both directions, and the increase is significant in the abduction (p < 0.01). The Fugl–Myer motor assessment score is improved greatly in the shoulder-related items (p < 0.01), but neither in the shoulder-unrelated items of the upper extremity (p = 0.13) nor in the lower extremity items (p = 0.19). This pilot study demonstrates that EMG-controlled assistive exercise can improve shoulder motor functions related to selected muscles and the suggested method is promising for the motor recovery of the shoulder in chronic hemiplegia.

Mental workload is an important component in complex human-machine systems. The limited applicability of empirical workload measures produces the need for workload modeling and prediction methods. In the present study, a mental workload prediction model is built on the basis of attentional resource allocation and information processing to ensure pilots’ accuracy and speed in understanding large amounts of flight information on the cockpit display interface. Validation with an empirical study of an abnormal attitude recovery task showed that this model’s prediction of mental workload highly correlated with experimental results. This mental workload prediction model provides a new tool for optimizing human factors interface design and reducing human errors.

The objective of this study is to build a fuzzy linguistic prediction model (FLPM) for analyzing the actuation duration of acute hyperglycemia to sinoatrial node field potential. The field potential was recorded using microelectrode arrays (MEA). The experimental data were analyzed using partial least squares (PLS), support vector machine (SVM), back propagation neural network (BPNN) and the proposed method. The experimental results showed that the fuzzy linguistic prediction model could be adopted for predicting the actuation duration of high glucose to the sinoatrial node field potential. Compared with the other aforementioned models, the proposed model had higher prediction accuracy.

In this paper, participants operated visual display terminals (VDT); the authors analyzed their pulse wave signals to develop objective indices for diagnosing and assessing VDT-induced. The experiment used 30 healthy undergraduates test subjects; each subject operated static PC for 4 hours. The pulse waves of local blood volumes in the test subjects’ finger-tips were measured every 30 minutes for 2 minutes. After the experiment, the pulse wave parameters were analyzed. All test subjects exhibited signs of visual fatigue according to the fatigue scale results. There were significant differences of heart rate (HR), which clearly declined before and after the experiment (P<0.01). The indexes RMSSD, SDNN, P3, P4, P5, P6, and TP had significant differences (P<0.01) and all rose. The positions of the main and dicrotic waves advanced (P<0.01). The experiment parameters prompted significant changes; pulse wave forms changed during VDT work. Based on these results, pulse wave analysis holds promise as an effective, noninvasive technique for measuring VDT fatigue.

Lung carcinoma has become one of the malignancies whose morbidity and mortality are growing significantly. Blood is a functional body fluid, it delivers oxygen and nutrients to the other parts of the body, and it is a pathway of tumor metastasis. This paper studies the possibility of diagnosing lung carcinoma by blood dielectric spectroscopy. Comparison experiments were carried out to trace the dielectric spectroscopy of blood with and without lung carcinoma changing at different tumor stages from 100 Hz to 100 MHz. The research results show that the discrepancy of complex permittivity between rat blood with and without lung carcinoma becomes significant with tumor growing, which is worthy for clinical diagnosis.

Non-contact and remote measurements of vital physical signals are important for reliable and comfortable physiological self-assessment. We presented a novel optical imaging-based method to measure the vital physical signals. Using a digital camera and ambient light, the cardiovascular pulse waves were extracted better from human color facial videos correctly. And the vital physiological parameters like heart rate were measured using a proposed signal-weighted analysis method. The measured HRs consistent with those measured simultaneously with reference technologies (r=0.94, p<0.001 for HR). The results show that the imaging–based method is suitable for measuring the physiological parameters, and provide a reliable and comfortable measurement mode. The study lays a physical foundation for measuring multi-physiological parameters of human noninvasively.

Fluorescence dye DiR and superparamagnetic iron oxide nanoparticles (SPIONs) embedded in PEG-PLGA nanobubbles (DiR-SPIO-NBs) were produced using double emulsion method on a membrane of Shirasu porous glass (SPG). The nanobubbles encapsulated with DiR and SPIONs had a liquid core (perfluoropentane) and a PEG-PLGA shell. DiR-SPIO-NBs showed biocompatibility based on MTT cytotoxicity and hemolysis studies. The PFP encapsulated in the nanobubbles experienced phase transition under ultrasonic irradation. Nanobubbles dispersed well in saline over 3 months, and the relaxivity was 127.9 mM⁻¹s⁻¹, suggesting that it could be used as a contrast agent in MRI. The MR and fluorescence images in vivo demonstrated that the signal intensity in the spleen and liver was significantly enhanced with the treatment of nanobubbles. In addition, results of ultrasound images suggested that the nanobubbles had persistent contrast ability. In conclusion, nanobubbles could be utilized as an US/MRI/fluorescence contrast agent.

In a previous study (unpublished), Emotiv headset was validated for capturing event-related potentials (ERPs) from normal subjects. In the present follow-up study, the signal quality of Emotiv headset was tested by the accuracy rate of discriminating Major Depressive Disorder (MDD) patients from the normal subjects. ERPs of 22 MDD patients and 15 normal subjects were induced by an auditory oddball task and the amplitude of N1, N2 and P3 of ERP components were specifically analyzed. The features of ERPs were statistically investigated. It is found that Emotiv headset is capable of discriminating the abnormal N1, N2 and P3 components in MDD patients. Relief-F algorithm was applied to all features for feature selection. The selected features were then input to a linear discriminant analysis (LDA) classifier with leave-one-out cross-validation to characterize the ERP features of MDD. 127 possible combinations out of the selected 7 ERP features were classified using LDA. The best classification accuracy was achieved to be 89.66%. These results suggest that MDD patients are identifiable from normal subjects by ERPs measured by Emotiv headset.

This paper improves the learning dictionary construction method for morphological component analysis (MCA) to separate the atrial and ventricular signals. The incoherence is added into the objective function to reduce the sparsity ratio between the atrial and ventricular dictionaries. By using the dictionaries, atrial and ventricular activities are separated from the location of the coefficients. We test the methods on both the synthetic and real atrial data. While extracting AFW from synthetic data, we use the Poisson relation as the measure. The result shows that we can obtain greater relation value using the method this paper presents than using the methods of ABS and PCA. We also conduct spectral analysis on AFW extracted from real atrial data.

This paper presents an analog front-end (AFE) IC design for recording biopotential signals. The AFE employs a capacitively coupled instrumentation amplifier to achieve a low-noise and high-common mode rejection ratio (CMRR) system. A ripple reduction loop is proposed to reduce the ripple generated by the up-modulating chopper. The low frequency noise is attenuated by an input AC coupling capacitor, and is attenuated again by a DC servo loop. The proposed AFE features a differential gain of 71 dB, and a CMRR of 89 dB, at 50 Hz. Furthermore, the proposed AFE can robustly acquire biopotential signals even in the presence of an input offset and ripples.

Fiducial Localization Error (FLE) is one of the major reasons of inaccuracy in point-based spatial registration of Image-Guided Neurosurgery System (IGNS), and minimizing FLE is the fundamental way to improve spatial registration accuracy. A reliable estimation of FLE is needed, as it cannot be measured directly in real application of IGNS. In this paper, we propose a method to estimate the FLE in a point-based registration of IGNS. Test fiducial point sets were generated in one coordinate system around the given fiducial point set by utilizing simple random sampling. Further, these points were registered to the fiducial point set in the other coordinate system. The average position of the test fiducial point sets with small FRE are calculated and its displacement from the given fiducial point set is the parameter used to estimate the FLE of each fiducial point. The correlation between the displacement and the FLE of each fiducial point is greater than 0.75 when nine or more fiducial points were utilized. This correlation gradually increases up to 0.9 with the increase of the number of fiducial points.

Laser Doppler imagery is a contemporary form biomedical science specializing in non-evasive micro-circulation investigation. This paper outlines the process and results of applying twelve different test samples to mouse skin to collect data variation of micro-circulation, then judge the effects of different formulas in skin health improvement. More specifically, it is said [15] that micro-circulation is associated with anti-aging (otherwise known as micro-circulation acceleration) by the way of improvement of nutrition supply and hazard substance elimination, has some effects of skin anti-aging. In this paper, compared with Group 0 (the blank group), Group 1, and Group 2 formulas have statistically significant differences in skin micro-circulation perfusion, which implies that those two groups are provided with better anti-aging formulas. So, Group 1’s formula and Group 2’s formula have the most significant positive effect on the skin health.

Electromagnetic compatibility (EMC) is a key issue in the design and development of safe and effective medical instruments. The treatment probes of high intensity focused ultrasound (HIFU) systems not only receive and transmit electromagnetic waves, but also radiate ultrasound waves, resulting in electromagnetic coupling. In this paper, an electromagnetic shielding method involving the enclosure of the probe in a copper wire mesh was introduced. First, sound pressure distribution simulations and measurements were performed using a hydrophone in order to evaluate the effects of the wire mesh on the acoustic performance of the HIFU system. The results indicated that the wire mesh did not disturb the normalized sound pressure field. In addition, the attenuation of the maximum pressure in the focal plane was equal to 6.2%. Then, the electronic emission level was tested in a chamber. After the implementation of the wire mesh, the 10-100 MHz frequency band radiation was suppressed, and the HIFU system satisfied the national EMC standards.

This study presents a novel spatial registration method of Image-guided neurosurgery system (IGNS) based on stereo-vision. Images of the patient’s head are captured by a video camera, which is calibrated and tracked by an optical tracking system. Then, a set of sparse facial data points are reconstructed from them by stereo vision in the patient space. Surface matching method is utilized to register the reconstructed sparse points and the facial surface reconstructed from preoperative images of the patient. Simulation experiments verified the feasibility of the proposed method. The proposed method it is a new low-cost and easy-to-use spatial registration method for IGNS, with good prospects for clinical application.

Support vector machine (SVM) is one of the most effective classification methods for cancer detection. The efficiency and quality of a SVM classifier depends strongly on several important features and a set of proper parameters. Here, a series of classification analyses, with one set of photoacoustic data from ovarian tissues ex vivo and a widely used breast cancer dataset- the Wisconsin Diagnostic Breast Cancer (WDBC), revealed the different accuracy of a SVM classification in terms of the number of features used and the parameters selected. A pattern recognition system is proposed by means of SVM-Recursive Feature Elimination (RFE) with the Radial Basis Function (RBF) kernel. To improve the effectiveness and robustness of the system, an optimized tuning ensemble algorithm called as SVM-RFE(C) with correlation filter was implemented to quantify feature and parameter information based on cross validation. The proposed algorithm is first demonstrated outperforming SVM-RFE on WDBC. Then the best accuracy of 94.643% and sensitivity of 94.595% were achieved when using SVM-RFE(C) to test 57 new PAT data from 19 patients. The experiment results show that the classifier constructed with SVM-RFE(C) algorithm is able to learn additional information from new data and has significant potential in ovarian cancer diagnosis.

A grid-driven gridding (GDG) method is proposed to uniformly re-sample non-Cartesian raw data acquired in PROPELLER, in which a trajectory window for each Cartesian grid is first computed. The intensity of the reconstructed image at this grid is the weighted average of raw data in this window. Taking consider of the single instruction multiple data (SIMD) property of the proposed GDG, a CUDA accelerated method is then proposed to improve the performance of the proposed GDG. Two groups of raw data sampled by PROPELLER in two resolutions are reconstructed by the proposed method. To balance computation resources of the GPU and obtain the best performance improvement, four thread-block strategies are adopted. Experimental results demonstrate that although the proposed GDG is more time consuming than traditional DDG, the CUDA accelerated GDG is almost 10 times faster than traditional DDG.

Diffusion tensor imaging allows for the non-invasive in vivo mapping of the brain tractography. However, fiber bundles have complex structures such as fiber crossings, fiber branchings and fibers with large curvatures that tensor imaging (DTI) cannot accurately handle. This study presents a novel brain white matter tractography method using Q-ball imaging as the data source instead of DTI, because QBI can provide accurate information about multiple fiber crossings and branchings in a single voxel using an orientation distribution function (ODF). The presented method also uses graph theory to construct the Bayesian model-based graph, so that the fiber tracking between two voxels can be represented as the shortest path in a graph. Our experiment showed that our new method can accurately handle brain white matter fiber crossings and branchings, and reconstruct brain tractograhpy both in phantom data and real brain data.

Laser can precisely deliver quantitative energy to a desired region in a non-contact way. Since it can stimulate regions and minutely control parameters such as the intensity, duration and frequency of stimulus, laser is often used for the areas such as low power laser treatment and clinical physiology. This study proposes simulation using pulse diode laser with reliable output and identifies laser parameters that can present a variety of somesthesis. It is found that typically, as frequency and energy increase, the ratio of feeling senses increases, and dominant sense moves from the sense of heat through tactile sense to pain. This study will be baseline data for studies of the sense of heat, tactile sense and pain, contribute to studying neurophysiology sector and be applied to basic clinical research.

Segmentation technique is widely accepted to reduce noise propagation from transmission scanning for positron emission tomography. The conventional routine is to sequentially perform reconstruction and segmentation. A smoothness penalty is also usually used to reduce noise, which can be imposed to both the ML and WLS estimators. In this paper we replace the smoothness penalty by a segmentation penalty that biases the object toward piecewise-homogeneous reconstruction. Two updating algorithms are developed to solve the penalized ML and WLS estimates, which monotonically decrease the cost functions. Experimental results on simulated phantom and real clinical data were both given to demonstrate the effectiveness and efficiency of the algorithms which were proposed.

This paper aims to solve automated feature selection problem in brain computer interface (BCI). In order to automate feature selection process, we proposed a novel EEG feature selection method based on decision tree (DT). During the electroencephalogram (EEG) signal processing, a feature extraction method based on principle component analysis (PCA) was used, and the selection process based on decision tree was performed by searching the feature space and automatically selecting optimal features. Considering that EEG signals are a series of non-linear signals, a generalized linear classifier named support vector machine (SVM) was chosen. In order to test the validity of the proposed method, we applied the EEG feature selection method based on decision tree to BCI Competition II datasets Ia, and the experiment showed encouraging results.

Computed tomography (CT) has been widely used to acquire volumetric anatomical information in the diagnosis and treatment of illnesses in many clinics. However, the ART algorithm for reconstruction from under-sampled and noisy projection is still time-consuming. It is the goal of our work to improve a block-wise approximate parallel implementation for the ART algorithm on CUDA-enabled GPU to make the ART algorithm applicable to the clinical environment. The resulting method has several compelling features: (1) the rays are allotted into blocks, making the rays in the same block parallel; (2) GPU implementation caters to the actual industrial and medical application demand. We test the algorithm on a digital shepp-logan phantom, and the results indicate that our method is more efficient than the existing CPU implementation. The high computation efficiency achieved in our algorithm makes it possible for clinicians to obtain real-time 3D images.

Radiotherapy treatment plan may be replanned due the changes of tumors and organs at risk (OARs) during the treatment. Deformable image registration (DIR) based Computed Tomography (CT) contour propagation in the routine clinical setting is expected to reduce time needed for necessary manual tumors and OARs delineations and increase the efficiency of replanning. In this study, a DIR method was developed for CT contour propagation. Prior structure delineations were incorporated into Demons DIR, which was represented by adding an intensity matching term of the delineated tissues pairs to the energy function of Demons. The performance of our DIR was evaluated with five clinical head-and-neck and five lung cancer cases. The experimental results verified the improved accuracy of the proposed registration method compared with conventional registration and Demons DIR.

Arrhythmia diagnosis is very significant to ensure human health. In this paper, a new model is developed for arrhythmia diagnosis. A salient feature of the algorithm is a synergistic combination of statistical and fuzzy set-based techniques. It is distribution-free and is realized in an unsupervised mode. Arrhythmia diagnosis is viewed as a certain statistical hypothesis testing. ‘Abnormal’ is typically a much complex concept, so it can be described with the technology of fuzzy sets which bring a facet of robustness to the overall scheme and play an important role in the successive step of hypothesis testing. Intensive fuzzification is engaged in parameters determination which is self-adaptive and no parameter needs to be specified by the user. The algorithm is validated with a number of experiments, which prove its effectiveness for arrhythmia diagnosis.

Epilepsy is a neurological disorder characterized by the sudden abnormal discharging of brain neurons that can lead to encephalographic (EEG) abnormalities. In this study, data was obtained from epileptic patients with intracranial depth electrodes and analyzed using wavelet entropy algorithms in order to locate the epileptic foci. Significant increases in the wavelet entropy of the epileptic signals were identified during multiple episodes of clinical seizures. The results indicated that the algorithm was capable of identifying entropy changes in the epileptic sources. Furthermore, the correlations among the electrocorticogram (ECoG) signals of different channels determined using the amplitude-amplitude coupling method verified that the epileptic foci exhibited significantly higher coupling strengths. Thus, cross frequency coupling (CFC) could be an inspiration to energy and signal transitive mode of seizure and, thereby, improve diagnostic processes.

Based on the idea of telemedicine, 24-hour uninterrupted monitoring on electrocardiograms (ECG) has started to be implemented. To create an intelligent ECG monitoring system, an efficient and quick detection algorithm for the characteristic waveforms is needed. This paper aims to give a quick and effective method for detecting QRS-complexes and R-waves in ECGs. The real ECG signal from the MIT-BIH Arrhythmia Database is used for the performance evaluation. The method proposed combined a wavelet transform and the K-means clustering algorithm. A wavelet transform is adopted in the data analysis and preprocessing. Then, based on the slope information of the filtered data, a segmented K-means clustering method is adopted to detect the QRS region. Detection of the R-peak is based on comparing the local amplitudes in each QRS region, which is different from other approaches, and the time cost of R-wave detection is reduced. Of the tested 8 records (total 18201 beats) from the MIT-BIH Arrhythmia Database, an average R-peak detection sensitivity of 99.72 and a positive predictive value of 99.80% are gained; the average time consumed detecting a 30-min original signal is 5.78s, which is competitive with other methods.

This paper briefly describes the basic principle of wavelet packet analysis, and on this basis introduces the general principle of wavelet packet transformation for signal den-noising. The dynamic EEG data under +Gz acceleration is made a de-noising treatment by using wavelet packet transformation, and the de-noising effects with different thresholds are made a comparison. The study verifies the validity and application value of wavelet packet threshold method for the de-noising of dynamic EEG data under +Gz acceleration.

This paper presents a technical solution that analyses sleep signals captured by biomedical sensors to find possible disorders during rest. Specifically, the method evaluates electrooculogram (EOG) signals, skin conductance (GSR), air flow (AS), and body temperature. Next, a quantitative sleep quality analysis determines significant changes in the biological signals, and any similarities between them in a given time period. Filtering techniques such as the Fourier transform method and IIR filters process the signal and identify significant variations. Once these changes have been identified, all significant data is compared and a quantitative and statistical analysis is carried out to determine the level of a person’s rest. To evaluate the correlation and significant differences, a statistical analysis has been calculated showing correlation between EOG and AS signals (p=0,005), EOG, and GSR signals (p=0,037) and, finally, the EOG and Body temperature (p=0,04). Doctors could use this information to monitor changes within a patient.

The very first step to process electrocardiogram (ECG) signal is to eliminate baseline wandering interference that is usually caused by electrode-skin impedance mismatch, motion artifacts due to a patient’s body moment or respiratory breathing. A new method is thus suggested to remove baseline wandering in ECG by improving the detrending method that was originally proposed for eliminating slow non-stationary trends from heart rate variability (HRV). In our proposed method, a global trend is estimated in terms of baseline wandering by merging the local trend based on an ECG segment that represents a part of the ECG signal. The experimental results show that the improved detrending method can efficiently resolve baseline wandering without distorting any morphological characteristic embedded in the ECG signal in no time delay manner.

The heart sound signal is a reflection of heart and vascular system motion. Long-term continuous electrocardiogram (ECG) contains important information which can be helpful to prevent heart failure. A single piece of a long-term ECG recording usually consists of more than one hundred thousand data points in length, making it difficult to derive hidden features that may be reflected through dynamic ECG monitoring, which is also very time-consuming to analyze. In this paper, a Dynamic Time Warping based on MapReduce (MRDTW) is proposed to make prognoses of possible lesions in patients. Through comparison of a real-time ECG of a patient with the reference sets of normal and problematic cardiac waveforms, the experimental results reveal that our approach not only retains high accuracy, but also greatly improves the efficiency of the similarity measure in dynamic ECG series.

Recently, exploring the cognitive functions of the brain by establishing a network model to understand the working mechanism of the brain has become a popular research topic in the field of neuroscience. In this study, electroencephalography (EEG) was used to collect data from subjects given four different mathematical cognitive tasks: recite numbers clockwise and counter-clockwise, and letters clockwise and counter-clockwise to build a complex brain function network (BFN). By studying the connectivity features and parameters of those brain functional networks, it was found that the average clustering coefficient is much larger than its corresponding random network and the average shortest path length is similar to the corresponding random networks, which clearly shows the characteristics of the small-world network. The brain regions stimulated during the experiment are consistent with traditional cognitive science regarding learning, memory, comprehension, and other rational judgment results. The new method of complex networking involves studying the mathematical cognitive process of reciting, providing an effective research foundation for exploring the relationship between brain cognition and human learning skills and memory. This could help detect memory deficits early in young and mentally handicapped children, and help scientists understand the causes of cognitive brain disorders.

Unrecognized spatial disorientation (SD) which is intimately linked with brain cognitive function is always a fatal issue for the safety of pilots. To explore its effects on human brain cognitive functions, electroencephalography (EEG) functional network analysis methods were adopted to examine topological changes in the connection of cognitive regions when experiencing unrecognized SD. Twelve male pilots participated in the study. They were subjected to a SD scene, namely visual rotation, which evoked unrecognized SD. For the main EEG frequency intervals, the phase lag index (PLI) and normalized mutual information (NMI) were calculated to quantify the EEG data. Then weighted connectivity networks were constructed and their properties were characterized in terms of an average clustering coefficient and global efficiency. A T-test was performed to compare PLI, NMI and network measures under unrecognized SD and non-SD conditions. It indicated a weak functional connectivity level in the theta band under unrecognized SD based on the significant decrease of mean values of PLI and NMI (p<0.05). Meanwhile, both the average clustering coefficient and global efficiency in the theta band reduced under the unrecognized SD condition. The decrease of the average clustering coefficient and global efficiency demonstrates a lack of small-world characteristics and a decline in processing efficiency of brain cognitive regions. All the experimental results show that unrecognized SD may have a negative effect on brain functional networks in the theta band.

Motor imagery EEG-based BCI has advantages in the assistance of human control of peripheral devices, such as the mobile robot or wheelchair, because the subject is not exposed to any stimulation and suffers no risk of fatigue. However, the intensive training necessary to recognize the numerous classes of data makes it hard to control these nonholonomic mobile systems accurately and effectively. This paper proposes a new approach which combines motor imagery EEG with the Adaptive Neural Fuzzy Inference System. This approach fuses the intelligence of humans based on motor imagery EEG with the precise capabilities of a mobile system based on ANFIS. This approach realizes a multi-level control, which makes the nonholonomic mobile system highly controllably without stopping or relying on sensor information. Also, because the ANFIS controller can be trained while performing the control task, control accuracy and efficiency is increased for the user. Experimental results of the nonholonomic mobile robot verify the effectiveness of this approach.

The use of electroencephalograms (EEGs) to diagnose and analyses Alzheimer’s disease (AD) has received much attention in recent years. The sample entropy (SE) has been widely applied to the diagnosis of AD. In our study, nine EEGs from 21 scalp electrodes in 3 AD patients and 9 EEGs from 3 age-matched controls are recorded. The calculations show that the kurtoses of the AD patients’ EEG are positive and much higher than that of the controls. This finding encourages us to introduce a kurtosis-based de-noising method. The 21-electrode EEG is first decomposed using independent component analysis (ICA), and second sort them using their kurtoses in ascending order. Finally, the subspace of EEG signal using back projection of only the last five components is reconstructed. SE will be calculated after the above de-noising preprocess. The classifications show that this method can significantly improve the accuracy of SE-based diagnosis. The kurtosis analysis of EEG may contribute to increasing the understanding of brain dysfunction in AD in a statistical way.

In this paper we report a detection method for different sleep stages and it is based on a single-channel electroencephalogram (EEG) system. The system is simple and can be easily setup in homes to perform sleep EEG recording, overnight sleep EEG automatic staging, and sleep quality evaluation. EEG data of 14 sleeping subjects were recorded through the entire night. All subjects were within the age group of 20-30 years and having no significant sleep disorders. To analyze the EEG data, it is segmented into equal time intervals. This is followed by calculation of Sample Entropy (SampEn) for each section, and the SampEn’s statistical characteristics, such as the median, upper quartile, lower quartile and inter-quartile range. The sleep data were divided into training group (7 cases) and test group (7 cases). Sleep stages’ quantitative ranges of training group referring to ZEO results were extracted and the quantization range used to sleep staging EEG data. Both the training group and test group results were close to ZEO results. It suggested that the statistical characteristics of Sample Entropy could be used as a criterion for sleep staging and evaluation.

This paper explores the application of multifractal detrended fluctuation analysis (MF-DFA) on the nonlinear characteristics of correlation between operation force and surface electromyography (sEMG), which is an applied frontier of human neuromuscular system activity. We established cross-correlation functions between the signal of force and four typical sEMG time-frequency domain index sequences (force-sEMG cross-correlation sequences), and dealt with the sequences with MF-DFA. In addition, we demonstrated that the force-sEMG cross-correlation sequences have strong statistical self-similarity and the fractal characteristic of the signal spectrum is similar to 1/f noise or fractional Brownian motion.

This study investigated the correlation between AQP4 expression and DTI in rat brainstems after diffuse axonal injuries (DAI). Forty rats were imaged before injury and reimaged at 3, 6, 12, 24 and 72 h post-injury. A control group of 8 rats was imaged and sacrificed for histology but not injured. After brain injury, AQP4 expression and ADC values in the brainstems increased gradually, reaching peak values at 24 h and 12 h, respectively. FA values decreased within 72 h. There was a negative correlation between ADC values and brainstem AQP4 expression at 12 h, and a positive correlation at 24 h or 72 h ( P < 0.01 ), respectively. Changes in the ADC and FA values in the brainstems indicated brain edema and severe axonal injuries. The correlations between AQP4 expression and time-dependent ADC values aid in understanding brain edema development after DAI.

Methods based on the magnetic-acoustic effect are of great significance in studying the electrical imaging properties of biological tissues and currents. The continuous wave method, which is commonly used, can only detect the current amplitude without the sound source position. Although the pulse mode adopted in magneto-acoustic imaging can locate the sonic source, the low measuring accuracy and low SNR has limited its application. In this study, a vector method was used to solve and analyze the magnetic-acoustic signal based on the continuous sine wave mode. This study includes theory modeling of the vector method, simulations to the line model, and experiments with wire samples to analyze magneto-acoustic (MA) signal characteristics. The results showed that the amplitude and phase of the MA signal contained the location information of the sonic source. The amplitude and phase obeyed the vector theory in the complex plane. This study sets a foundation for a new technique to locate sonic sources for biomedical imaging of tissue conductivity. It also aids in studying biological current detecting and reconstruction based on the magneto-acoustic effect.

Decoding brain states from response patterns with multivariate pattern recognition techniques is a popular method for detecting multivoxel patterns of brain activation. These patterns are informative with respect to a subject’s perceptual or cognitive states. Linear discriminant analysis (LDA) cannot be directly applied to fMRI data analysis because of the “few samples and large features” nature of functional magnetic resonance imaging (fMRI) data. Although several improved LDA methods have been used in fMRI-based decoding, little is known regarding the relative performance of different LDA classifiers on fMRI data. In this study, we compared five LDA classifiers using both simulated data with varied noise levels and real fMRI data. The compared LDA classifiers include LDA combined with PCA (LDA-PCA), LDA with three types of regularizations (identity matrix, diagonal matrix and scaled identity matrix) and LDA with optimal-shrinkage covariance estimator using Ledoit and Wolf lemma (LDA-LW). The results indicated that LDA-LW was the most robust to noises. Moreover, LDA-LW and LDA with scaled identity matrix showed better stability and classification accuracy than the other methods. LDA-LW demonstrated the best overall performance.

In this study, the radiation generated in the diagnosis of scoliosis, to solve the problems by using an infrared camera and an optical marker system that can diagnose scoliosis developed. System developed by the infrared camera attached to the optical spinal curvature is recognized as a marker to shoot the angle between the two optical markers are measured. Measurement of angle, we used the Cobb’s Angle method used in the diagnosis of spinal scoliosis. We developed a software to be able to output to the screen using an infrared camera to diagnose spinal scoliosis. Software is composed of camera output unit was manufactured in Labview, angle measurement unit, in Cobb’s Angle measurement unit. In the future, kyphosis, Hallux Valgus, such as the diagnosis of orthopedic disorders that require the use of a diagnostic system is expected case.

In this work, abundant anticorrelated networks were successfully detected in rest-stating fMRI-BOLD data from 20 subjects. Spatial independent component analysis (sICA) method was applied at both individual and group levels. At the individual level, for each subject, 30 independent components (IC) were estimated, and each IC was transformed using Z-score mapping. The voxels with >5 and < -5 Z-score were denoted as positive signals (PS) and negative signals (NS) respectively. The correlation coefficients between the mean time series of the PS and NS voxels were computed; if the calculated coefficients were <-0.3, the PS and NS voxels were considered to form an anticorrelated PS-NS network. It was found that 36.5% of the ICs contained an anticorrelated PS-NS network. The spatiotemporal patterns of most PS-NS networks varied from subject to subject, but three networks displaying spatial patterns were comparably consistent among different subjects. For group-level analysis, no anticorrelated PS-NS networks were detected. Our results suggest that future investigations adopt a broader approach for negative BOLD signal characterization. Combined consideration of PS and NS systems help to better elucidate hemodynamic and neuronal brain behavior and further develop understanding of neural mechanisms of brain information processing.

In this study, a computer-aided detection (CAD) system was developed for the detection of lung nodules in computed tomography images. The CAD system consists of four phases, including two-dimensional and three-dimensional preprocessing phases. In the feature extraction phase, four different groups of features are extracted from volume of interests: morphological features, statistical and histogram features, statistical and histogram features of outer surface, and texture features of outer surface. The support vector machine algorithm is optimized using particle swarm optimization for classification. The CAD system provides 97.37% sensitivity, 86.38% selectivity, 88.97% accuracy and 2.7 false positive per scan using three groups of classification features. After the inclusion of outer surface texture features, classification results of the CAD system reaches 98.03% sensitivity, 87.71% selectivity, 90.12% accuracy and 2.45 false positive per scan. Experimental results demonstrate that outer surface texture features of nodule candidates are useful to increase sensitivity and decrease the number of false positives in the detection of lung nodules in computed tomography images.

Here we developed a real-time photoacoustic tomography (PAT) imaging acquisition device based on the linear array transducer utilized on ultrasonic devices. Also, we produced a phantom including diverse contrast media and acquired PAT imaging as the light source wavelength was changing to see if the contrast media reacted. Indocyanine green showed the highest reaction around the 800-nm band, methylene blue demonstrated the same in the 750-nm band, and gold nanoparticle showed the same in the 700-nm band. However, in the case of superparamagnetic iron oxide, we observed not reaction within the wavelength bands used herein to obtain imaging. Moreover, we applied selective filtering to the acquired PAT imaging to remove noise from around and reinforce the object’s area. Consequentially, we could see the object area in the imaging was effectively detected and the image noise was removed.

To improve the speed and accuracy of cerebral vessel extraction, a fast and robust method is proposed in this paper. First, volume data are divided into sub-volumes by using octree, and at the same time invalid volume data are eliminated. Second, fuzzy connectedness is introduced to achieve fast cerebral vessel segmentation from 3D MRA Images. The values of gradient and Laplacian transformation are then calculated to improve the accuracy of the distance field. Last, the center of gravity is utilized to refine the initial centerline to make it closer to the actual centerline of the vessel cavity. The experiment demonstrates that the proposed method can effectively improve the speed and precision of centerline extraction.

Pelger-Huet anomaly (PHA) and Pseudo Pelger-Huet anomaly (PPHA) are neutrophil with abnormal morphology. They have the bilobed or unilobed nucleus and excessive clumping chromatin. Currently, detection of this kind of cell mainly depends on the manual microscopic examination by a clinician, thus, the quality of detection is limited by the efficiency and a certain subjective consciousness of the clinician. In this paper, a detection method for PHA and PPHA is proposed based on karyomorphism and chromatin distribution features. Firstly, the skeleton of the nucleus is extracted using an augmented Fast Marching Method (AFMM) and width distribution is obtained through distance transform. Then, caryoplastin in the nucleus is extracted based on Speeded Up Robust Features (SURF) and a K-nearest-neighbor (KNN) classifier is constructed to analyze the features. Experiment shows that the sensitivity and specificity of this method achieved 87.5% and 83.33%, which means that the detection accuracy of PHA is acceptable. Meanwhile, the detection method should be helpful to the automatic morphological classification of blood cells.

In this paper, we propose a computer information processing algorithm that can be used for biomedical image processing and disease prediction. A biomedical image is considered a data object in a multi-dimensional space. Each dimension is a feature that can be used for disease diagnosis. We introduce a new concept of the top ( k 1 , k 2 ) outlier. It can be used to detect abnormal data objects in the multi-dimensional space. This technique focuses on uncertain space, where each data object has several possible instances with distinct probabilities. We design an efficient sampling algorithm for the top ( k 1 , k 2 ) outlier in uncertain space. Some improvement techniques are used for acceleration. Experiments show our methods’ high accuracy and high efficiency.

Retinal prostheses have the potential to restore some level of visual function to the patients suffering from retinal degeneration. In this paper, an epiretinal approach with active stimulation devices is presented. The MEMS-based processing system consists of an external micro-camera, an information processor, an implanted electrical stimulator and a microelectrode array. The image processing strategy combining image clustering and enhancement techniques was proposed and evaluated by psychophysical experiments. The results indicated that the image processing strategy improved the visual performance compared with direct merging pixels to low resolution. The image processing methods assist epiretinal prosthesis for vision restoration.

Due to the inherent speckling and low contrast of ultrasonic images, the accurate and efficient location of regions of interest (ROIs) is still a challenging task for breast ultrasound (BUS) computer-aided diagnosis (CAD) systems. In this paper, a fully automatic and efficient ROI generation approach is proposed. First, a BUS image is preprocessed to improve image quality. Second, a phase of max-energy orientation (PMO) image of the preprocessed image is calculated. Otsu’s threshold selection method is then used to binarize the preprocessed image, the phase image and the composed image obtained by adding and normalizing the set of two images. Finally, a region selection algorithm is developed to select the true tumor region from these three binary images before generating a final ROI. The method was validated on a BUS database with 168 cases (81 benign and 87 malignant); the accuracy, average precision rate and average recall rate are calculated and compared with conventional method. The results indicate that the proposed method is more accurate and efficient in locating ROIs.

Noise is one of the main sources of quality deterioration not only for visual inspection but also in computerized processing in brain magnetic resonance (MR) image analysis such as tissue classification, segmentation and registration. Accordingly, noise removal in brain MR images is important for a wide variety of subsequent processing applications. However, most existing denoising algorithms require laborious tuning of parameters that are often sensitive to specific image features and textures. Automation of these parameters through artificial intelligence techniques will be highly beneficial. In the present study, an artificial neural network associated with image texture feature analysis is proposed to establish a predictable parameter model and automate the denoising procedure. In the proposed approach, a total of 83 image attributes were extracted based on four categories: 1) Basic image statistics. 2) Gray-level co-occurrence matrix (GLCM). 3) Gray-level run-length matrix (GLRLM) and 4) Tamura texture features. To obtain the ranking of discrimination in these texture features, a paired-samples t-test was applied to each individual image feature computed in every image. Subsequently, the sequential forward selection (SFS) method was used to select the best texture features according to the ranking of discrimination. The selected optimal features were further incorporated into a back propagation neural network to establish a predictable parameter model. A wide variety of MR images with various scenarios were adopted to evaluate the performance of the proposed framework. Experimental results indicated that this new automation system accurately predicted the bilateral filtering parameters and effectively removed the noise in a number of MR images. Comparing to the manually tuned filtering process, our approach not only produced better denoised results but also saved significant processing time.

With the aim of developing an accurate pathological brain detection system, we proposed a novel automatic computer-aided diagnosis (CAD) to detect pathological brains from normal brains obtained by magnetic resonance imaging (MRI) scanning. The problem still remained a challenge for technicians and clinicians, since MR imaging generated an exceptionally large information dataset. A new two-step approach was proposed in this study. We used wavelet entropy (WE) and Hu moment invariants (HMI) for feature extraction, and the generalized eigenvalue proximal support vector machine (GEPSVM) for classification. To further enhance classification accuracy, the popular radial basis function (RBF) kernel was employed. The 10 runs of k-fold stratified cross validation result showed that the proposed “WE + HMI + GEPSVM + RBF” method was superior to existing methods w.r.t. classification accuracy. It obtained the average classification accuracies of 100%, 100%, and 99.45% over Dataset-66, Dataset-160, and Dataset-255, respectively. The proposed method is effective and can be applied to realistic use.

Level set method has been widely used in medical image analysis, but it has difficulties when being used in the segmentation of left ventricular (LV) boundaries on echocardiography images because the boundaries are not very distinguish, and the signal-to-noise ratio of echocardiography images is not very high. In this paper, we introduce the Active Shape Model (ASM) into the traditional level set method to enforce shape constraints. It improves the accuracy of boundary detection and makes the evolution more efficient. The experiments conducted on the real cardiac ultrasound image sequences show a positive and promising result.

3D anatomical feature curves (AFC) on bone models reconstructed from CT/MRI images are important in some fields, such as preoperative planning, intra-operative navigation, patient-specific prosthesis design, etc. Interactive extraction of feature curves on patient-specific bone models is time-consuming, has low repeatability and accuracy. This paper presents a computer graphics method to automatically extract AFC from 3D hip bone models reconstructed from CT images. A DCSS (direct curvature scale space)-based technique is firstly used to extract anatomical feature points (AFP) in every contour, using anatomical structure information as prior knowledge so that AFP are extracted and only extracted. Then, corresponding AFP are linked in different contours and AFC is generated. AFC obtained by our method were compared with those interactively extracted by three surgeons, which showed that our method is feasible (Dice coefficient: 0.94; Average symmetric surface distance: 3.97 mm). The method was also applied to identify anatomical landmarks, which showed that our method is superior to the curvature-based methods that fail to identify landmark regions or have too many redundant regions, which results in failures to subsequently label landmark regions using pre-defined spatial adjacency matrices.

For quantitative analysis of glioma, multimodal Magnetic Resonance Imaging (MRI) signals are required in combination to perform a complementary analysis of morphological, metabolic, and functional changes. Most of the morphological analyses are based on T1-weighted and T2-weighted signals, called traditional MRI. But more detailed information about tumorous tissues could not be explained. An information combination scheme of Diffusion-Weighted Imaging (DWI) and Blood-Oxygen-Level Dependent (BOLD) contrast Imaging is proposed in this paper. This is a non-model segmentation scheme of brain glioma tissues in a particular perspective of combining multi-parameters of DWI and BOLD contrast functional Magnetic Resonance Imaging (fMRI). Compared with traditional MRI, a promising advantage of our work is to provide an effective and adequate subdivision of the related pathological regions with glioma, by incorporating both knowledge of image graylevel and spatial structure. Furthermore, it is an automatic segmentation method without needs of parameter selection and model fitting for the extracted tissues. By the experiments in patients with glioma, the proposed method has achieved the average overlap ratios of 83.6% in the whole tumor region and 82.5% in the peritumoral edema region with the manual segmentation as “ground truth”.

In this study, we develop a new algorithm based on fractional operators of variable-order in order to enhance image quality. First, three kinds of popular high-order discrete formulas are adopted to obtain the coefficients, and subsequently, a mask optimization method for selecting the fractional order adaptively is applied to construct a variable-order fractional differential mask along with the coefficients generated from the first step. We carry out experiments on OCT thoracic aorta images and some nature images with low contrast and noise, demonstrating that the high-order discrete method leads to significantly better performance in enhancing the edge information nonlinearly compared to the standard first-order discrete method. Moreover, the optimized mask with variable-order of the fractional derivative not only can preserve the edge information of the processed images adequately, but it also effectively suppresses the noise in the smooth area.

An automatic method for estimating the density of cell nuclei in whole slide images (WSI’s) of hepatic histological sections is presented. The method can be applied to hematoxylin-eosin (H&E) stained sections with slight histological atypism, such as early well-differentiated hepatocellular carcinoma (ewHCC). It is shown that measured nuclear density is affected by the nuclear size due to fragments of nuclei. This size-dependent problem has been solved by estimating the standard nuclear area for each image patch. The method extracts typical nuclei, which are used to automatically adjust the parameters, including the standard nuclear area. The method is robust for variations in contrast, color, and nuclear size. 40 image patches sampled from 20 WSI’s of surgical sections were used for accuracy evaluation. The mean absolute percentage error of estimated nuclear densities was 8.2%. It was also confirmed that the distributions of nuclear density were successfully estimated and visualized for all 20 WSI’s. The computation time for a WSI of typical surgical section (754 mm², about 1,280,000 nuclei) was about 57 minutes on a PC.

Multi-threshold image segmentation is a powerful image processing technique that is used for the preprocessing of pattern recognition and computer vision. However, traditional multilevel thresholding methods are computationally expensive because they involve exhaustively searching the optimal thresholds to optimize the objective functions. To overcome this drawback, this paper proposes a flower pollination algorithm with a randomized location modification. The proposed algorithm is used to find optimal threshold values for maximizing Otsu’s objective functions with regard to eight medical grayscale images. When benchmarked against other state-of-the-art evolutionary algorithms, the new algorithm proves itself to be robust and effective through numerical experimental results including Otsu’s objective values and standard deviations.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is widely used for breast lesion differentiation. Manual segmentation in DCE-MRI is difficult and open to viewer interpretation. In this paper, an automatic segmentation method based on image manifold revealing was introduced to overcome the problems of the currently used method. First, high dimensional datasets were constructed from a dynamic image series. Next, an embedded image manifold was revealed in the feature image by nonlinear dimensionality reduction technique. In the last stage, k-means clustering was performed to obtain final segmentation results. The proposed method was applied in actual clinical cases and compared with the gold standard. Statistical analysis showed that the proposed method achieved an acceptable accuracy, sensitivity, and specificity rates.

In this paper, a fully automatic scheme for measuring liver volume in 3D MR images was developed. The proposed MRI liver volumetry scheme consisted of four main stages. First, the preprocessing stage was applied to T1-weighted MR images of the liver in the portal-venous phase to reduce noise. The histogram of the 3D image was determined, and the second-to-last peak of the histogram was calculated using a neural network. Thresholds, which are determined based upon the second-to-last peak, were used to generate a thresholding image. This thresholding image was refined using a gradient magnitude image. The morphological and connected component operations were applied to the refined image to generate the rough shape of the liver. A 3D geodesic-active-contour segmentation algorithm refined the rough shape in order to more precisely determine the liver boundaries. The liver volumes determined by the proposed automatic volumetry were compared to those manually traced by radiologists; these manual volumes were used as a “gold standard.” The two volumetric methods reached an excellent agreement. The Dice overlap coefficient and the average accuracy were 91.0 ±2.8% and 99.0 ±0.4%, respectively. The mean processing time for the proposed automatic scheme was 1.02 ±0.08 min (CPU: Intel, core i7, 2.8GHz), whereas that of the manual volumetry was 24.3 ±3.7 min (p < 0.001).

Pinhole SPECT for small animal has become a routine procedure in many applications of molecular biology and pharmaceutical development. There is an increasing demand in the whole body imaging of lab animals. A simple and direct solution is to scan the object along a helical trajectory, similar to a helical CT scan. The corresponding acquisition time can be greatly reduced, while the over-lapping and gap between consecutive bed positions can be avoided. However, helical pinhole SPECT inevitably leads to the tremendous increase in computational complexity when the iterative reconstruction algorithms are applied. We suggest a novel voxel-driven (VD) system model which can be integrated with geometric symmetries from helical trajectory for fast iterative image reconstruction. Such a model construction can also achieve faster calculation and lower storage requirement of the system matrix. Due to the independence among various symmetries, it permits parallel coding to further boost computation efficiency of forward/backward projection. From phantom study, the results also indicate that the proposed VD model can adequately model the helical pinhole SPECT scanner with manageable storage size of system matrix and clinically acceptable computation loading of reconstruction.

Static imaging of the electrical impedance tomography can obtain the absolute electrical conductivity distribution at one section of the subject. The test is performed on a cylinder physical phantom in which slim rectangle, hollow cylinder, small rectangle or three cylinders are selected to simulate complex conductivity perturbation objects. The measurement data is obtained by a data acquisition system with 32 compound electrodes. A group of static images of conductivity distribution in the cylinder phantom are reconstructed by the modified Newton-Raphson algorithm with two kinds of regularization methods. The results show correct position, size, conductivity difference, and similar shape of the perturbation objects in the images.

Low-dose computed tomography reconstruction is an important issue in the medical imaging domain. Sparse-view has been widely studied as a potential strategy. Compressed sensing (CS) method has shown great potential to reconstruct high-quality CT images from sparse-view projection data. Nonetheless, low-contrast structures tend to be blurred by the total variation (TV, L₁-norm of the gradient image) regularization. Moreover, TV will produce blocky effects on smooth and edge regions. To overcome this limitation, this study has proposed an iterative image reconstruction algorithm by combining L₁ regularization and smoothed L₀ (SL₀) regularization. SL₀ is a smooth approximation of L₀ norm and can solve the problem of L₀ norm being sensitive to noise. To evaluate the proposed method, both qualitative and quantitative studies were conducted on a digital Shepp-Logan phantom and a real head phantom. Experimental comparative results have indicated that the proposed L₁/SL₀-POCS algorithm can effectively suppress noise and artifacts, as well as preserve more structural information compared to other existing methods.