Prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta and lower limbs

Purpose The aim of this study was to assess the prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta (AA-CTA) and lower limbs (LL-CTA). Materials and methods The images of 536 AA-CTA and LL-CTA examinations performed for suspected aortic and peripheral vascular disease in 500 patients were retrospectively reviewed. Two radiologists evaluated the 5-mm axial images independently using appropriate window settings for the area under investigation. Collateral findings were divided according to their clinical significance into significant, nonsignificant and meriting further investigation. Results No collateral findings were identified in 97/500 patients (19.4%). In the remaining patients, 821 collateral findings were detected, of which 43 (5.24%) were classified as significant, 135 (16.44%) as meriting further investigation and 643 (78.32%) as nonsignificant. The findings indicative of the presence of a malignant lesion totalled 36 (4.5%). Conclusions AA-CTA and LL-CTA demonstrate a nonnegligible prevalence of collateral findings, many of them major. It therefore appears that the evaluation should focus not only on the image reconstructions to identify vascular disease, but also on the native axial images to detect incidental findings.