Axial unenhanced lumbar spine CT scans in a 50-year-old man demonstrate increased conspicuity of a slightly hyperattenuating, lobulated left renal mass (arrow) on the full-FOV spinal image. Source: Radiology (doi: 10.1148/radiol.12112152)

Full-field-of-view (FOV) images from lumbar spine CT exams will show many incidental findings; however, most will be benign and only a small number of extraspinal pathologic findings will have substantial clinical importance, according to a study published online March 21 in Radiology.

Current practice in CT of the lumbar spine is to limit the FOV to the spine, but this means potentially important findings outside of the FOV may be missed entirely, explained study authors Andrew E. Leung, MD, and colleagues from the department of medical imaging at London Health Sciences Centre-University Hospital in Ontario, Canada. Their study was designed to determine the prevalence and clinical importance of these extraspinal abnormalities.

“Findings outside the region of interest may result in the early detection of potentially curable disease, which raises an ethical issue in regard to the practice of excluding scanned data from review. However, working up benign incidental findings in otherwise asymptomatic patients may also lead to increased morbidity and expense,” they wrote.

The authors conducted a prospective study of 400 consecutive adult outpatients undergoing lumbar spine CT for lower back pain and/or radiculopathy. Patients were followed for two to three years after the initial CT to determine outcomes.

Results showed that 162 exams had extraspinal findings. Some patients had two or three findings, for an overall total of 201 findings. A full-FOV was required to best visualize the extraspinal abnormalities in 79.4 percent of cases.

The majority of these findings, however, were benign and did not require further work-up. Fifty-nine patients had indeterminate or potentially important findings requiring further evaluation. Substantial extraspinal pathologic findings were present in 4.3 percent of patients. These significant findings consisted of early-stage renal cell carcinoma, transitional cell carcinoma, chronic lymphocytic leukemia, sarcoidosis and abdominal aortic aneurysms.

“Because routine review of the full-FOV abdominal images is not currently performed in most centers, careful consideration of the benefits and risks of routinely reviewing the entire scanned volume on images from lumbar spine CT examinations is needed,” wrote Leung et al.

The authors wrote that their findings are relevant to debates regarding incidental findings in other exams. In cardiac CT, for example, they noted that current practice in lumbar spine CT is cited as an argument against including extracardiac structures from the analysis of cardiac CT scans.