Incidence of highly important extravascular findings detected on CT angiography of the abdominal aorta and the lower extremities

OBJECTIVE. The purpose of this study was to determine the frequency and significance of extravascular findings on CT angiography of the abdominal aorta and lower extremities. MATERIALS AND METHODS. Reports of CT angiograms of the abdominal aorta and lower extremities for 275 patients (164 men and 111 women; mean age, 72 years) were retrospectively reviewed. Patients were scanned from the level of diaphragm to toes. Extravascular findings were classified into three groups - low, moderate, and high importance - on the basis of clinical significance. Low-importance findings were defined as those with little, if any, clinical significance. Moderate-importance findings were those that may not be clinically apparent but recognition of which could be beneficial at a later time. Highly important findings were defined as previously unknown results requiring further imaging or investigation. For highly important findings, electronic chart review determined the subsequent clinical course. RESULTS. Highly important extravascular findings were found in 40 (15%) patients. Of 462 findings overall, 43 (9%) were of high importance, 77 (17%) were of moderate importance, and 342 (74%) were of low importance. The most common highly important findings were indeterminate lesions of kidney (n = 9), lung (n = 7), and liver (n = 6). Overall, eight (3%) of the 275 patients had findings of high clinical significance that resulted in medical therapy or surgical intervention, including lung carcinoma, renal cell carcinoma, colon carcinoma, cholangiocarcinoma, and pulmonary coccidioidomycosis. CONCLUSION. Of patients undergoing CT angiography of the abdominal aorta and lower extremities, 15% had previously undiagnosed, highly important findings. Radiologists and referring clinicians should be aware of the frequency of these clinically significant extravascular findings at CT angiography.