Incidental findings on renal MR angiography

OBJECTIVE. The purpose of this article is to assess the incidence of incidental vascular and nonvascular findings in patients undergoing renal MR angiography and to determine the extent to which these findings alter patient management. MATERIALS AND METHODS. Reports from 380 consecutive renal MR angiography examinations performed at a single institution over a 12-month interval were examined. The presence of incidental vascular (i.e., nonrenal artery) and nonvascular findings was noted. Clinical records of patients with significant incidental findings were examined to determine whether additional imaging, biopsy, or surgery was performed. RESULTS. Overall, 151 (40%) of 380 patients had one or more additional vascular findings not related to the renal arteries, and 221 (58%) of 380 patients had one or more additional nonvascular findings. Vascular findings included mesenteric artery stenosis or occlusion in 33% of patients, moderate to severe aortic atherosclerosis in 17%, aortic aneurysms in 7%, and aortic dissection in 2%. Incidental malignancies were detected in 10 patients (3%), and indeterminate lesions requiring follow-up imaging, biopsy, or surgery were noted in 18 patients (5%). Overall, management in 5% of patients was significantly altered (i.e., required biopsy, surgery, or other intervention) by incidental findings detected on renal MR angiography. Benign lesions not requiring additional imaging or follow-up occurred in 54% of patients and consisted predominantly of renal cysts. CONCLUSION. Incidental findings on renal MR angiography are common. Most incidental lesions can be adequately detected and characterized with the addition of a few pulse sequences to the standard renal MR angiography protocol at a minimal cost in imaging time. The high incidence of incidental findings emphasizes the importance of performance and interpretation of these examinations by physicians with training in abdominal cross-sectional imaging.