Accuracy of Centerline of Flow Measurement for Sizing of the Zenith AAA Endovascular Graft and Predictive Factor for Risk of Inadequate Sizing

The purpose of this study was to evaluate the accuracy of centerline of flow (CLF) measurement for precise sizing of the Zenith AAA endovascular graft (Zenith) and to identify predictive factors of risk of inadequate endograft sizing. We analyzed 42 consecutive patients treated using the Zenith with pre- and postoperative multidetector CT between 2001 and 2007. Endograft sizing was retrospectively performed using CLF on a three-dimensional workstation. The following parameters were investigated: (a) change in distance from lowest renal artery to hypogastric artery between CLF on preoperative CT (CLFp) and CLF of graft path on postoperative CT (CLFg); (b) supposed success rate of adequate endograft length selection; and (c) predictive factors for significant alteration (>10 mm) between CLFp and CLFg. Median change in distance from lowest renal artery to hypogastric artery was 4 mm. CLFg was >10 mm shorter than CLFp in 10 of 84 limbs (12%). Multivariate analysis demonstrated tortuosity index (TI) of infrarenal abdominal aorta (p = 0.019), aneurysm diameter (p = 0.035), and ipsilateral side of the main body insertion (p = 0.042) as predictive factors of significant alteration between CLFp and CLFg. Adequate endograft length selection was achieved in 39 of 42 cases (93%). All three inadequate endograft length selections were associated with tortuous aorta (TI > 20 mm). In conclusion, distance calculations based on CLF measurement provided accurate length selection of the Zenith in the majority of cases. TI, aneurysm diameter, and ipsilateral side were predictive factors for significant alteration. The CLF and aortic measurements including the TI may allow for improved sizing for Zenith placements.