Abdominal aortic aneurysm morphology in candidates for endovascular repairevaluated with spiral computed tomography and digital subtraction angiography

Purpose: To analyze the morphology of abdominal aortic aneurysms (AAAs) and to study the usefulness of spiral computed tomography (CT) versus digital subtraction angiography (DSA) in the evaluation of patients for endovascula r repair. Methods: Of 133 AAA patients (120 men, mean age 67 years, range 52 to 84) e valuated preoperatively with CT imaging, 77 endograft candidates (68 men) w ere also assessed with intra-arterial DSA. Arterial parameters were measure d on axial CT scans and angiographic films for comparison. Results: Mean maximum AAA diameter was 58 +/- 11 mm (range 39 to 95). Aneur ysmal neck diameter was consistently smaller on DSA than on CT (20.7 +/- 3. 6 mm versus 23.0 +/- 3.5 mm, p < 0.0001). The distance from the most distal renal artery to the aortic bifurcation was longer on angiography than on C T (mean difference 10.0 mm, p < 0.0001). There was a positive correlation b etween the maximum AAA diameter and the AAA length (r = 0.49, p < 0.0001) a nd an inverse relationship between the neck length and the neck diameter (r = -0.36, p < 0.0001). No correlation was found between the maximum AAA dia meter and maximum iliac diameter, angulation, or length. Conclusions: AAA anatomy varies widely and independently of the aneurysm si ze. Therefore, the maximum size of the aneurysm is a poor predictor of whet her or not an aneurysm is suitable for endovascular repair. The discrepancy between angiographic and axial CT measurements suggests that neither alone is sufficient as a preoperative imaging technique when evaluating a patien t for an endovascular graft procedure.