Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT): a comparative evaluation of VasoCT and intravascular OCT

Abstract

BACKGROUND: Poor vessel wall apposition of flow diverter (FD) stents poses risks for stroke-related complications when treating intracranial aneurysms, necessitating long-term surveillance imaging. To facilitate quantitative evaluation of deployed devices, a novel algorithm is presented that generates intuitive two-dimensional representations of wall apposition from either high-resolution contrast-enhanced cone-beam CT (VasoCT) or intravascular optical coherence tomography (OCT) images. METHODS: VasoCT and OCT images were obtained after FD implant (n=8 aneurysms) in an experimental sidewall aneurysm model in canines. Surface models of the vessel wall and FD device were extracted, and the distance between them was presented on a two-dimensional flattened map. Maps and cross-sections at potential locations of malapposition detected on VasoCT-based maps were compared. The performance of OCT-based apposition detection was evaluated on manually labeled cross-sections using logistic regression against a thresholded ( \u3e /=0.25 mm) apposition measure. RESULTS: VasoCT and OCT acquisitions yielded similar Grading of Regional Apposition after Flow-Diverter Treatment (GRAFT) apposition maps. GRAFT maps from VasoCT highlighted 16 potential locations of malapposition, of which two were found to represent malapposed device struts. Logistic regression showed that OCT could detect malapposition with a sensitivity of 98% and a specificity of 81%. CONCLUSIONS: GRAFT delivered quantitative and visually convenient representations of potential FD malapposition and occasional acute thrombus formation. A powerful combination for future neuroendovascular applications is foreseen with the superior resolution delivered by intravascular OCT

Risk Factors for Ischemic Complications following Pipeline Embolization Device Treatment of Intracranial Aneurysms: Results from the IntrePED Study

“…22 It is thought that poor wall apposition can result in delayed endothelialization of the stent, resulting in an increased risk of instent thrombosis in the delayed postoperative period. 20,21 This is supported by the fact that the fusiform aneurysms that were associated with stroke in our series were generally large or giant, with a mean aneurysm size of nearly 25 mm and a mean neck size of 26 mm. The large aneurysm maximum diameter and neck size likely made achieving good wall apposition, thus increasing the risk of in-stent thrombosis.…”

“…A number of studies have reported poor outcomes and high rates of thrombosis in the treatment of dolichoectatic and fusiform aneurysms, particularly of the posterior circulation, with flow diverters in general. 9,20,21 High rates of infarction seen in these patients are likely due to a combination of poor wall apposition due to the large size of the aneurysm, early discontinuation of antiplatelet therapy, and the requirement for multiple PEDs. 20,21 Recently, there has been increased interest in the relationship between wall apposition of the flow diverter and rates of delayed postoperative stroke.…”

“…9,20,21 High rates of infarction seen in these patients are likely due to a combination of poor wall apposition due to the large size of the aneurysm, early discontinuation of antiplatelet therapy, and the requirement for multiple PEDs. 20,21 Recently, there has been increased interest in the relationship between wall apposition of the flow diverter and rates of delayed postoperative stroke. 22 It is thought that poor wall apposition can result in delayed endothelialization of the stent, resulting in an increased risk of instent thrombosis in the delayed postoperative period.…”

“…As a means to mitigate the risk of delayed thromboembolic events in the treatment of fusiform aneurysms secondary to delayed endothelialization, some authors have advocated the use of prolonged dual-antiplatelet therapy. 21 However, the efficacy of such regimens needs to be studied systematically.…”

Fast acquisition cone-beam computed tomography: initial experience with a 10 s protocol

“…On the one hand, still-developing tools such as optical coherence tomography offer more invasive methods for evaluating the vasculature and endovascular devices with high fidelity 10. High-resolution CBCT protocols also aim for the same bar, to reach even higher resolution.…”