The abdominal aortic aneurysm sac after endoluminal exclusion: A medium-term morphologic follow-up based on volumetric technology

Purpose: The purpose of this study was to evaluate the role of three-dimens ional spiral computed tomographic angiography (SCTA) for the assessment of the feasibility and results of endoluminal repair of infrarenal abdominal a ortic aneurysm. Methods: Laboratory studies: Phantom glass aneurysms, filled with contrast, underwent SCTA. The correlation between SCTA. and laboratory measurements of linear dimensions and volumes was highly accurate (r(2) = 1.0). Clinical studies: From the first: 7 patients that were suitable for endoluminal rep air, the correlation between SCTA and angiocatheter measurements was 0.85 t o 0.99 (P < .04), but there was poor agreement between individual values. A s determined from the measurements by 2 experienced investigators, intraobs erver and interobserver errors for volume calculation in 12 randomly chosen scans from a total of 120 scans were 5.7 and 4.4 mL, respectively (range o f volumes, 100-403 mt). The conditions of 53 patients were judged suitable for endoluminal repair of which 30 patients reached 1 year or more follow-u p. The median aneurysm neck length and diameter were 24.5 mm (range, 11.5-6 0.8 mm) and 23.4 mm (18.3-31.5 mm), respectively. The fate of the sac after endografting by two techniques (pre-expanded polytetrafluoroethylene [PTFE ] fixed with Palmaz stents and endografts) was defined with three-dimension al SCTA. Results: The sac volume after endografting by pre-expanded PTFE (n = 12 pat ients) showed a significant median increase (P = .02) from 129 mt before su rgery to 141 mi; at 5 days after the operation with no change at 6 (139 mt) , 12 (137 mit), and 18 (159 mt) months later. With the endografts (n = 18), there was an initial increase in median volume at 5 days (179-194 mt; P = .02) and then a significant shrinkage at 6 (148 mt; P = .012) and 12 (94.9 mt; P = .02) months. Conclusion: Three-dimensional SCTA has been validated and is both precise a nd reliable. Interobserver and intraobserver errors are within acceptable r anges, Angiocatheter measurements are less accurate and may give misleading information when used far patient selection and endograft construction. Th e sac volume increased after endografting and later shrank in patients who were treated with endografts, but not. in those patients treated with pre-e xpanded PTFE. We propose that three-dimensional SCTA should be regarded as the gold standard for linear and volumetric measurement for infrarenal abdo minal aortic aneurysm.