Differences in Cardiac-Pulsatility-Induced Displacement and Geometry Changes between the Cook ZBIS and Gore IBE: Postoperative Comparison Using ECG-Gated CTA Scans

Abstract

To what extent the stentgraft design of iliac branch devices (IBDs) relates to dynamic deformation is currently unknown. Therefore, this study aimed to quantify and compare displacement and geometry changes during the cardiac cycle of two common IBDs. This paper presents a two-center trial with patients treated with a Zenith bifurcated iliac side (ZBIS) or Gore iliac branch endoprosthesis (IBE). All patients underwent a retrospective electrocardiogram (ECG)-gated computed tomographic angiography (CTA) during follow-up. Cardiac-pulsatility-induced displacement was quantified for the following locations: (neo) bifurcation of the aorta, IBD flow divider, distal markers of the internal iliac artery (IIA) component and first IIA bifurcation. Geometrical parameters (length, tortuosity index, curvature and torsion) were quantified over centerlines. Displacement was more pronounced for the IBE than the ZBIS, e.g., craniocaudal displacement of 0.91 mm (0.91–1.13 mm) vs. 0.57 mm (0.40–0.75 mm, p = 0.004), respectively. The IBDs demonstrated similar geometrical parameters in the neo-common iliac artery and distal IIA, except for the larger dynamic curvature and torsion of the distal IIA in IBEs. The IBEs showed more dynamic length and curvature change compared to the ZBIS in the stented IIA. The IIA trajectory showed more pronounced deformation during the cardiac cycle after placement of an IBE than a ZBIS, suggesting the IBE is more conformable than the ZBIS.

The influence of electrocardiogram-gated computed tomography reconstruction into 8 or 10 cardiac phases on cardiac-pulsatility-induced motion quantification of stent grafts in the aorta

“…The dynamic behavior of stent grafts in the aorta has been reported in literature, 3 , 4 , 9 , 13 , 21 , 22 , 23 , 24 including papers that have implemented the same image registration and segmentation techniques as applied in the present study. 3 , 4 , 13 , 21 , 22 Validation of these algorithms has been performed by Koenrades et al, 2 including accuracy assessment for motion calculation in ECG-gated CT scans with reconstructions into 10 phases on CT scanners from two vendors (Somatom Definition Flash as used in the current study and the Aquilion 64, Toshiba Medical Systems Corporation, Otawara City, Tochigi Prefecture, Japan). For this validation, they used an experimental setup and found an absolute error of at most 0.3 mm for motion calculation, with average errors of 0.12 and 0.14 mm for the respective scanners.…”

“…Theoretically, quantifying cardiac-pulsatility-induced motion with 8 or 10 phases in an ECG-gated CT angiography might be an undersampling of the motion signal, especially for reconstructions into 8 phases. For example, Simmering et al 13 investigated the postoperative behavior of 2 different iliac branched devices, scanned with different scanning protocols: reconstruction into 8 phases or 10 phases on a Philips Brilliance iCT 256 scanner. Initially, there may have been doubt as to whether the observed difference between the stent grafts was caused by the stent graft type or the scan type.…”

“…This is achieved by simultaneously collecting the ECG and CT data and reconstructing CT volumes from raw CT data acquired during the predefined cardiac phases. 5 , 6 Retrospective ECG-gated CT scans have been used to investigate motion and deformation of the aorta and its stent grafts during the cardiac cycle 1 , 2 , 3 , 7 , 8 , 9 , 10 , 11 , 12 , 13 However, the number of cardiac phases into which the CT data was reconstructed varied between these studies as some had reconstructed the CT into 8 phases and others into 10 phases, rendering the comparability between studies uncertain. Moreover, as ECG-gated CT scans are becoming more and more frequent in both clinical trials and clinical workflow, the importance of accurate comparability among different scan protocols and CT scanners of different vendors increases further.…”

Innovative Imaging Techniques: Nice to Have or Essential to Treat Complex Diseases?

“…On the other hand, two research groups showed that standard CT angiography (CTA) alone does not suffice when attempting to understand the dynamics of the abdominal aorta that includes implanted stent grafts. In their retrospective series, Simmering and coworkers used electrocardiogram (ECG)-gated CTA to determine the geometry changes in two different types of iliac branch devices for the treatment of common iliac artery aneurysms [2]. In addition to the iliac arteries, ECG-gated CTA may be of great help to study the geometry changes in thoracic and abdominal aortic endografts during the cardiac cycle, their influence on cardiac function, as well as the (changed) compliance of the thoraco-abdominal aorta post endovascular repair of aortic aneurysms (EVAR).…”