PREOPERATIVE CLASSIFICATION OF ABDOMINAL AORTIC-ANEURYSMS WITH SPIRALCT - THE AXIAL SOURCE IMAGES REVISITED

Objective: The differentiation of supra-, juxta- and high infrarenal a bdominal aortic aneurysms (AAA), which is essential for good surgical management, remains problematic, This prospective study assessed the v alue of highly overlapping vs. contiguous axial spiral computed tomogr aphy (CT) reconstructions in the pre-operative assessment of AAA. Pati ents and methods: Thirty-five patients with abdominal aortic aneurysms were studied with spiral CT (10 mm collimation, pitch 1), Axial recon structions were performed at 2 and 10 mm increments and compared with surgical findings, Using each protocol, the aneurysms were classified as infra-, juxta- or suprarenal, Observers also assessed visualization of main and accessory renal artery origins and identification of othe r surgically relevant vascular anomalies. Results: The 2 mm protocol c orrectly identified 29/31 infrarenal, 3/3 juxtarenal and 1/1 suprarena l aneurysms; two infrarenal aneurysms were overestimated as suprarenal , The 10 mm protocol correctly classified 25/31 infrarenal, 3/3 juxtar enal and 1/1 suprarenal aneurysms; five infrarenal aneurysms were over estimated as juxtarenal (n = 3) or suprarenal (n = 2) and one case was equivocal, Correct classification was thus 94% using the 2 mm protoco l and 83% with the 10 mm protocol (P = 0.063), All 70 main renal arter y origins were visualized with the 2 mm protocol, while the 10 mm prot ocol missed six (P = 0.03) The 2 mm protocol identified 10 accessory r enal arteries, four of which were missed by the 10 mm protocol, Both p rotocols demonstrated five surgically relevant venous anomalies. Concl usion: Spiral CT with highly overlapping axial reconstructions correct ly classified 94% of abdominal aortic aneurysms; overlapping reconstru ctions were particularly useful in differentiating high infrarenal fro m juxtarenal aneurysms.