Rhinology Abstracts

Otolaryngology

Restricting Indications for Sinonasal Computed Tomography in Children with Cystic Fibrosis

Cavel O, Quintal MC, Marcotte JÉ, Garel L, Froehlich P. JAMA Otolaryngol Head Neck Surg 139:54–58, 2013

The vast majority of patients with cystic fibrosis (CF) suffer from chronic rhinosinusitis. Currently there are no accepted guidelines regarding imaging in this patient population. This study was intended to evaluate if limiting exposure to ionizing radiation in children with CF can be achieved through restricting the indications for sinonasal CT to the preoperative evaluation.

Cavel et al. retrospectively reviewed 277 patients with a diagnosis of CF over an 11 year period. 33 of these patients underwent 39 scans. They examined charts for symptoms/exam findings at time the scan was ordered, the clinical indication for ordering the CT, imaging findings and number of sinonasal procedures performed on each patient. Secondary to incomplete CT dosimetry data, the 75th percentile of the effective radiation dose (0.31 mSv) was assumed for the radiation dose for imaging performed before 2010. Afterwards, a low dose imaging protocol was adopted yielding in a radiation dose of 0.12 to 0.19 mSV. All patients were medically managed with nasal irrigations, twice daily nasal steroid sprays and short term oxymetazoline (during acute exacerbations). Patients were considered for surgery when medically refractory nasal obstruction or purulent rhinorrhea was present.

The average age of the patient at the conclusion of follow up was 13.7 years. Out of the 33 patients (12% of the total patients) that underwent CT scan, 39 total scans were performed over an 11 year period. This amounted to 0.018 scans per patient per year of follow-up. The indications for images ordered were preoperative planning (74%), rule out mucocele (5%), pre-lung transplant (5%), disease severity assessment (10%), headache evaluation (3%), and pre-orbital cellulitis (3%). The most common pathologies encountered on preoperative and non-preoperative imaging were frontal and/or sphenoid sinus hypoplasia, maxillary mucocele and partially obstructing nasal polyposis. Regarding scans that were ordered for non-preoperative assessments, 3/10 were ordered by an otolaryngologist and 7/10 were ordered by a pulmonologist.

Ultimately, this study demonstrated that through restricting indications for imaging, the overall rate of exposure to CT scans was limited to 12% of patients. This compared favorably to the quoted rate in the literature of CT scan exposure in CF children of 15–40%. Furthermore, Cavel added that the exposure rate would have been less if imaging had been solely restricted to preoperative planning. Additionally, the authors concluded that studies that were not ordered for preoperative planning did not change the treatment of the patients. They also reminded the reader that while CT is an accepted tool to evaluate the severity of the disease in patients without CF, there is a lack of correlation between imaging and symptom severity.

The strength of this study is that it presents imaging recommendations for the cystic fibrosis population; a population that ubiquitously suffers from chronic sinusitis and undergoes frequent imaging/radiation exposure in the face of longer life expectancies. They demonstrate a clear reduction in the number of studies that are performed when one attempts to apply a criteria for ordering imaging.

A relative weakness of this study is that the authors aim to demonstrate lower radiation exposure by employing a lose dose imaging protocol, but did not specifically state the total radiation dose that each patient received. Ultimately, it is unclear if the total radiation dose differences were significant.

Furthermore, the small size of this group and the retrospective nature of this paper limit the power of the study and its conclusions. Ultimately, one may argue that limiting indications for CT scans simply to pre-operative planning may be too stringent. For example, in cases of rhinosinusitis with concern for orbital complications, these criteria may be overly restrictive.

Overall, this is an interesting paper that provides evidence towards establishing formal criteria for sinonasal imaging in the CF patient population.

John M. Carter, M.D.

Ronald G. Amedee, M.D.