Impact of aortoiliac tortuosity on endovascular repair of abdominal aorticaneurysms: Evaluation of 3D computer-based assessment

Objective: The purpose of this study was to examine the effect of aortoilia c tortuosity, as assessed by observers and 3-dimensional (3D) computer-base d methods, on the conduct and outcome of endovascular repair of abdominal a ortic aneurysms. Methods: Infrarenal aortoiliac tortuosity was measured in 75 patients (mean follow-up, 14.8 +/- 10.4 months) who underwent endovascular repair of abdo minal aortic aneurysms by using the following four methods: (1) grading by 2 experienced observers; (2) tortuosity index measured as the inverse radiu s of curvature (cm(-1)) at 1-mm intervals along the median luminal centerli ne (MLC) on 3D reconstructions of computed tomography (CT) angiograms and w as calculated as the sum of values greater than 0.3 cm(-1); (3) MLC-straigh t line length ratio from renal to hypogastric arteries; (4) manual measurem ent of angles at points of angulation on anteroposterior and lateral projec tions of 3D CT reconstructions. In evaluating association between these mea sures, correlation between human observers was accepted as the gold standar d. Results. For rating of overall aortoiliac tortuosity, interobserver correla tion (r = 0.67) was comparable with correlation of observers with tortuosit y index (r = 0.67 and 0.56), whereas correlations of each observer with MLC -straight line ratio (r = 0.50 and 0.56) and cumulative angulation (r = 0.4 4 and 0.44) were significant but weaker. For determining the relative tortu osity of right and left aortoiliac access, agreement between observers and tortuosity index (54% and 58%; P <.05; <kappa>, 0.33 and 0.38) was not as g ood as between observers (68%; P <.001; <kappa>, 0.53). This difference was primarily related to evaluation of the aorta, where interobserver correlat ion (r = 0.71) was better than that between each observer and tortuosity in dex (r = 0.47 and 0.55), whereas correlations in the iliac arteries were co mparable (r = 0.64 and 0.67) (all coefficients P <.01). Increased tortuosit y was associated with a more complex endovascular repair, as reflected by l onger fluoroscopy time (P =.05), use of more contrast material (P =.03), us e of extender modules (P =.04), and more frequent use of arterial reconstru ction (P =.01), but was not associated with a higher overall complication r ate. Increased tortuosity, when it occurred in the aortic neck, was associa ted with predischarge endoleak (P =.03) but not with late endoleak, interve ntion, or aneurysm-related adverse events. Conclusion: Aortoiliac tortuosity is associated with increased complexity o f endovascular aneurysm repair and with predischarge endoleak but does not appear to affect intermediate-term results. Computer-based 3D measurement o f aortoiliac tortuosity is feasible and clinically meaningful. Its ultimate role in relation to human assessment must be further defined in future stu dies.