A comparison of three imaging techniques in the assessment of an abdominal aortic aneurysm.

Twenty-five patients undergoing elective surgery for large abdominal aortic aneurysms (AAAs) were investigated by preoperative ultrasonography (US), computed tomography (CT) or intravenous digital subtraction angiography (IV-DSA). The accuracy of each modality in assessing the upper and lower extent of aneurysmal disease was then compared. IV-DSA proved 100% accurate in assessing the relationship of the renal arteries to the aneurysm sac. Both CT and US overestimated the incidence of juxta or suprarenal AAAs and only had a predictive value for suprarenal disease of 13% and 14% respectively. If, however, US or CT stated the aneurysm to be infrarenal this was likely to be true though both investigations classified one suprarenal aneurysm as infrarenal. The distal extent of aneurysmal disease was again most accurately predicted by IV-DSA (predictive value 88%). Bowel gas frequently prevented US from visualizing the iliac arteries (19 of 25 cases). IV-DSA is a safe and accurate method for defining the relationship of an aneurysm to the renal arteries and should be adopted as a routine preoperative investigation of abdominal aneurysmal disease.