Canadian Association of Radiologists Journal

Dual-energy computed tomography (CT) is a promising tool with increasing availability and multiple emerging and established clinical applications in neuroradiology. With its ability to allow characterization of materials based on their differential attenuation when imaged at two different energy levels, dual-energy CT can help identify the composition of brain, neck, and spinal components. Virtual monoenergetic imaging allows a range of simulated single energy-level reconstructions to be created with postprocessing. Low-energy reconstructions can aid identification of edema, ischemia, and subtle lesions due to increased soft tissue contrast as well as increasing contrast-to-noise ratios on angiographic imaging. Higher energy reconstructions can reduce image artifact from dental amalgam, aneurysm clips and coils, spinal hardware, dense contrast, and dense bones. Differentiating iodine from hemorrhage may help guide management of patients after thrombectomy and aid diagnosis of enhancing tumors within parenchymal hemorrhages. Iodine quantification may predict hematoma expansion in aneurysmal bleeds and outcomes in traumatic brain injury. Calcium and bone subtraction can be used to distinguish hemorrhage from brain parenchymal mineralization as well as improving visualization of extra-axial lesions and vessels adjacent to dense plaque or skull. This article reviews the basics of dual-energy CT and highlights many of its clinical applications in the evaluation of acute neurological presentations.

Although acute ischemic stroke remains one of the most common causes of death and disability worldwide, it is a potentially treatable condition if appropriately managed in a timely manner. The goals of acute stroke imaging include establishing a diagnosis as fast as possible with (1) accurate infarct quantification, (2) intracranial and cervical vasculature assessment, and (3) brain perfusion analysis for detection of infarct core and potentially salvageable penumbra allowing optimal patient selection for appropriate therapy. Given the extensive number of images generated from acute stroke imaging studies and as “time is brain,” this article aims to highlight a logical approach for the radiologist in acute stroke computed tomography imaging in order to accurately interpret and communicate results in a timely manner.

Traumatic injuries of the cervical carotid and vertebral arteries, collectively referred to as blunt cerebrovascular injury (BCVI), can result in significant patient morbidity and mortality, with one of the most feared outcomes being cerebrovascular ischemia. Systematic imaging-guided screening for BCVI aims for early detection to guide timely management. In particular, accurate detection of the severity and grade of BCVI is paramount in guiding initial management. Furthermore, follow-up imaging is required to decide the duration of antithrombotic therapy. In this article, classification of the grades of BCVI and associated imaging findings will be outlined and diagnostic pitfalls and mimickers that can confound diagnosis will be described. In addition, updates to existing screening guidelines and recent efforts of criteria modification to improve detection of BCVI cases will be reviewed. The advent of postprocessing tools applied to conventional computed tomography (CT) angiograms and new diagnostic tools in dual energy CT for improved detection will also be discussed.

Emergency trauma radiology, although a relatively new subspecialty of radiology, plays a critical role in both the diagnosis/triage of acutely ill patients, but even more important in providing leadership and taking the lead in the preparedness of imaging departments in dealing with novel highly infectious communicable diseases and mass casualties. This has become even more apparent in dealing with COVID-19, the disease caused by the novel coronavirus SARS-CoV-2, first emerged in late 2019. We review the symptoms, epidemiology, and testing for this disease. We discuss characteristic imaging findings of COVID-19 in relation to other modern coronavirus diseases including SARS and MERS. We discuss roles that community radiology clinics, outpatient radiology departments, and emergency radiology departments can play in the diagnosis of this disease. We review practical methods to reduce spread of infections within radiology departments.

Traumatic cardiovascular injuries are only second to the central nervous system injuries as a cause of death in young adult population. Multidetector computed tomography is the gold standard diagnostic modality in patients with blunt or penetrating chest trauma and clinical suspicion of cardiac injury. The imaging spectrum of cardiac injuries includes but not limits to pericardial rupture, myocardial contusions, valve rupture, coronary artery injuries, cardiac herniations, and cardiac tamponade. In this review article, we discuss clinical presentation, types, and mechanism of cardiac trauma with emphasis on the imaging findings and illustrations in blunt, penetrating traumatic, and iatrogenic cardiac injuries.

Traumatic diaphragmatic injury (TDI) is an underdiagnosed condition that has recently increased in prevalence due to its association with automobile collisions. The initial injury is often obscured by concurrent thoracic and abdominal injuries. Traumatic diaphragmatic injury itself is rarely lethal at initial presentation, however associated injuries and complications of untreated TDI such as herniation and strangulation of abdominal viscera have serious clinical consequences. There are 2 primary mechanisms of TDIs: penetrating TDI which tend to be smaller, more difficult to detect, and result in fewer complications; and blunt TDIs which are larger and have higher overall mortality due to associated injuries or delayed complications. The anatomy of thoracic and abdominal cavities distinguishes the epidemiology, pathophysiology, symptoms, treatment, and prognosis of right versus left TDI. Although there is no definitive radiologic sign for diagnosing TDI, many signs have been introduced in the literature and the concurrent presence of multiple signs increases the sensitivity of TDI detection. Conservative versus surgical management depends on mechanism of TDI, side, and most importantly the associated injuries.

Aortic emergencies comprise of a list of conditions which are uncommon but are potentially fatal. Prognosis is usually determined by emergent diagnosis and treatment and hence radiology plays a key role in patient management. In this article, we aim to review the various causes of aortic emergencies and the relevant imaging findings placing special emphasis on acute aortic syndromes.

Here in Canada, we often think of gun violence as confined to conflict zones, terrorism, and more of a problem for our southern neighbor. However, in recent years, it has also become a Canadian problem with increased gun violence related to criminal activity presenting in daily practice. Radiologists play a critical role in the evaluation of ballistic trauma and must therefore be familiar with both the common and uncommon patterns of ballistic injury. In this article, we review the mechanisms of ballistic trauma as well as their resultant injury patterns in order to guide image interpretation.

This review aims to examine the challenges facing radiologists interpreting trauma computed tomography (CT) images in this era of a changing approach to management of solid organ trauma. After reviewing the pearls and pitfalls of CT imaging protocols for detection of traumatic solid organ injuries, we describe the key changes in the 2018 American Association for the Surgery of Trauma Organ Injury Scales for liver, spleen, and kidney and their implications for management strategies. We then focus on the important imaging findings in observed in patients who undergo nonoperative management and patients who are imaged post damage control surgery.

Since the advent of multidetecter computed tomography (CT), radiologist sensitivity in detection of traumatic bowel and mesenteric abnormalities has significantly improved. Although several CT signs have been described to identify intestinal injury, accurate interpretation of these findings can remain challenging. Early detection of bowel and mesenteric injury is important as it alters patient management, disposition, and follow-up. This article reviews the common imaging findings of traumatic small bowel and mesenteric injury.

Abdominal trauma, one of the leading causes of death under the age of 45, can be broadly classified into blunt and penetrating trauma, based on the mechanism of injury. Blunt abdominal trauma usually results from motor vehicle collisions, fall from heights, assaults, and sports and is more common than penetrating abdominal trauma, which is usually seen in firearm injuries and stab wounds. In both blunt and penetrating abdominal trauma, an optimized imaging approach is mandatory to exclude life-threatening injuries. Easy availability of the portable ultrasound in the emergency department and trauma bay makes it one of the most commonly used screening imaging modalities in the abdominal trauma, especially to exclude hemoperitoneum. Evaluation of the visceral and vascular injuries in a hemodynamically stable patient, however, warrants intravenous contrast-enhanced multidetector computed tomography scan. Dual-energy computed tomography with its postprocessing applications such as iodine selective imaging and virtual monoenergetic imaging can reliably depict the conspicuity of traumatic solid and hollow visceral and vascular injuries.

A mass casualty incident (MCI) is an event that generates more patients at one time than locally available resources can manage using routine procedures. By their nature, many of these incidents have no prior notice but result in large numbers of casualties with injuries that range in severity. They can happen anywhere and at any time and regional hospitals and health-care providers have to mount a response quickly and effectively to save as many lives as possible. Radiologists must go from passenger to pilot when it comes to MCI planning. When involved at the hospital-wide planning stage, they can offer valuable expertise on how radiology can improve triage accuracy and at what cost in terms of time and resources and thereby contribute a pragmatic understanding of radiology’s role and value during MCIs. By taking ownership of MCI planning in their own departments, radiologists can ensure that the radiology department can respond quickly and effectively to unforeseen emergencies. Well-designed radiology protocols will save lives in an MCI setting.

The use of diagnostic imaging studies in the emergency setting has increased dramatically over the past couple of decades. The emergency imaging of pregnant and lactating patients poses unique challenges and calls upon the crucial role of radiologists as consultants to the referring physician to guide appropriate use of imaging tests, minimize risk, ensure timely management, and occasionally alleviate unwarranted trepidation. A clear understanding of the risks and benefits involved with various imaging tests in this patient population is vital to achieve this. This review discusses the different safety and appropriateness issues that could arise with the use of ionizing radiation, iodinated-, and gadolinium-based contrast media and radiopharmaceuticals in pregnant and lactating patients. Special considerations such as trauma imaging, safety concerns with magnetic resonance imaging and ultrasound, management of claustrophobia, contrast extravasation, and allergic reactions are also reviewed. The consent process for these examinations has also been described.

As forensic radiology sees an exponential gain in popularity, postmortem computed tomography (PMCT) is increasingly being used in the appropriate setting, either as preautopsy guidance or as part of complementary virtual autopsy protocol. Many articles have expounded the value it adds to forensic pathology in the general setting and the appropriate technical parameters to be used for optimum benefit. We aim to put forth a concise review on the role of PMCT specifically in trauma and the pitfalls to be aware of. Reviews have shown that presumed cause of death in trauma have been proven by autopsy to be wrong in about 30% cases. Radiology applied to postmortem investigation in unnatural deaths and more specifically in trauma shares many semiotic features with emergency radiology. Therefore, in the near future, emergency radiologists might be required to integrate this type of imaging in their regular practice. Although the predominant drawbacks are time-dependent, PMCT also has some difficulty in differentiating antemortem and postmortem events. However, in many such scenarios, PMCT and autopsy play a complementary role in arriving at conclusions, and we believe understanding the benefits and role in trauma is imperative considering the expanding usage of PMCT.