Extraspinal Incidental Findings on Routine MRI of Lumbar Spine: Prevalence and Reporting Rates in 1278 Patients

OBJECTIVE The aim of the present study was to determine the prevalence and reporting rate of incidental findings (IF) in adult outpatients undergoing lumbar magnetic resonance imaging (MRI). MATERIALS AND METHODS Re-evaluation of a total of 1278 lumbar MRI images (collected from patients with a mean age of 50.5 years, range 16-91 years) captured between August 2010-August 2011 was done by a neuroradiologist and a musculoskeletal radiologist. IFs were classified according to organ or system (liver, gallbladder, kidney, bladder, uterus, ovary, lymph node, intestine and aorta). The rate of reporting of a range of IF was examined. The outcome of each patient's treatment was evaluated based on review of hospital records and by telephone interviews. RESULTS A total of 253 IFs were found in 241 patients (18.8% of 1278). Among these, clinically significant IFs (n = 34) included: 2 renal masses (0.15%), 2 aortic aneurysms (0.15%), 2 cases of hydronephrosis (0.15%), 11 adrenal masses (0.86%), 7 lymphadenopathies (0.55%), 6 cases of endometrial or cervical thickening (0.47%), 1 liver hemangioma (0.08%), 1 pelvic fluid (0.08%) and 2 ovarian dermoid cysts (0.15%). Overall, 28% (71/253) of IFs were included in the clinical reports, while clinically significant findings were reported in 41% (14/34) of cases. CONCLUSION Extraspinal IFs are commonly detected during a routine lumbar MRI, and many of these findings are not clinically significant. However, IFs including clinically important findings are occasionally omitted from formal radiological reports.