[Magnetic resonance: preoperative assessment of abdominal aortic aneurysms. Comparison with surgical findings in 80 cases]

This work was aimed at assessing Magnetic Resonance (MR) accuracy in the preoperative investigation of abdominal aortic aneurysms, with a view to suggesting MRI as the method of choice for surgical planning, replacing other relatively invasive investigation techniques like angiography and enhanced CT. In the last 3 years 80 patients with abdominal aortic aneurysms identified with US or CT were examined with 0.5-T MRI and underwent surgical repair within 15 days. Spin-echo (SE) T1-weighted axial, sagittal and coronal sequences were always performed. In 18 patients gradient-echo (GE) flow sequences were also acquired; SE T2-weighted sequences were used to study parietal thrombi in 10 patients and finally Gd-DTPA T1-weighted sequences were obtained in inflammatory aneurysms (3 patients). MR images were blindly evaluated by 2 radiologists. The following variables which are useful for surgical planning were considered for each patient: aneurysm extent, characteristics of parietal thrombi, dissections, fixurations, inflammation signs, involvement of renal arteries, vena cava, ureters, duodenum, the presence of retroaortic renal vein or of other anomalies or associated conditions. MR images were always compared with intraoperative findings, since surgery was considered as the gold standard. MR findings were in agreement with surgical findings in the evaluation of cranio-caudal aneurysm extent (78/80), parietal thrombus features (80/80), dissection (1/1) and fixuration signs (8/9), origin of renal arteries (80/80), inferior vena cava involvement (3/3), other anatomical anomalies or conditions (6/6). Inflammation signs were overestimated (14/8) as well as adhesion between aneurysm and duodenum (17/13). The presence of distal renal polar arteries was underestimated (2/4). In conclusion, MRI proves to be a highly sensitive method to demonstrate abdominal aortic aneurysms and is therefore suggested as the examination of choice before surgery.