The value of intraoperative intravascular ultrasound for determining stentgraft size (excluding abdominal aortic aneurysm) with a modular system

Since the introduction of endovascular stent grafts at our institution we h ave used intraoperative intravascular ultrasound (IVUS) to definitively det ermine stent graft size. In this study, expected stent graft size, based on preoperative helical CT scan measurements, was compared with the actual fi nal size, based on intraoperative IVUS measurements. Between December 1996 and January 1998, 54 patients were treated with an AneuRx(TM) bifurcated st ent graft. Preoperatively all patients underwent angiography and helical CT scanning. Expected stent graft size was determined according to these meas urements. The final stent graft size was based on IVUS measurements acquire d during the procedure. Differences in expected and final size were compare d and follow-up endoleaks were also noted. Differences in diameter measurem ents between CT and IVUS were compared using the paired Student's t-test. D ifferences in expected and chosen stent graft length were compared using th e McNemar's test for paired proportions of binomial outcomes. Our results s howed that helical CT scanning overestimates diameter and underestimates le ngth. This underestimation of length is explained by the tortuosity of the aorta and iliac arteries while using axial slices of the CT scan. The last- minute corrections based on the intraoperative IVUS measurements did not re sult in a high incidence of endoleaks at fixation zones. In our opinion, th e possibility of making final corrections in the choice of diameter or leng th of the stent graft is the additional value of intraoperative IVUS. DOI: 10.1007/s100169910067.