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

Abstract

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.

Impact of 3-Dimensional-Computed Tomography Workstation for Precise Planning of Endovascular Aneurysm Repair

“…The subject population was small. Although our previous retrospective study indicated tortuosity index of the infrarenal abdominal aorta >20 mm as a predictive factor for inadequate endograft design including the overlong main body, 14 median tortuosity index of the infrarenal aorta was 5 mm (range: 1-15 mm) in the present study. We do not make sure that CLF measurement can contribute to selection of device in patients with inadequate anatomy (exclusion criteria), especially severe tortuous neck.…”

“…Both axial CT and angiography with measurement catheters result in significant differences, particularly shortening. 9,14 There were statistically significant differences in measurements of L1, L2, and L3 between CLF measurement and axial CT measurement in this study. Moreover, there were several discrepancies in device size selected by between CLF measurement and axial CT measurement.…”

“…In our previous study, for regular devices, changes in distance from lowest renal artery to hypogastric artery between preoperative CLF measurement and postoperative graft path were 4mm. 14 We therefore consider that use of a 3D workstation could provide accurate sizing and placement of endografting for patients treated with EVAR, compensating for our lack of experience.…”

“…Limitations of it resulted from short cut of devices. 14 Considering tortuosity of arterial structures, a CLF image was produced with manual adjustment in the present study. Manual adjustment means adjustment for short-cut anticipated in patients with tortuous aorta or large aneurysm sac.…”

Repair of abdominal aortic aneurysms: preoperative imaging and evaluation

“…Sobocinski et al demonstrated that the proper utilization of a 3D workstation resulted in less type I endoleaks and secondary interventions when compared to preprocedure imaging evaluation solely by axial 2D CTA (48). CTA 3D reconstruction can also utilize a centerline flow rendering of the aorta and aneurysm, which produces orthogonal images that can be used for pre-procedure imaging evaluation for EVAR, providing an accurate method for aortic measurements (33,51,52). Production of orthogonal images minimizes the inaccurate measurements of a tortuous aorta by allowing for perpendicular measurements.…”