High Fidelity Virtual Stenting (HiFiVS) for Intracranial Aneurysm Flow Diversion: In Vitro and In Silico

Abstract

A flow diverter (FD) is a flexible, densely braided stent-mesh device placed endoluminally across an intracranial aneurysm to induce its thrombotic occlusion. FD treatment planning using computational virtual stenting and flow simulation requires accurate representation of the expanded FD geometry. We have recently developed a High Fidelity Virtual Stenting (HiFiVS) technique based on finite element analysis to simulate detailed FD deployment processes in patient-specific aneurysms (Ma et al. J. Biomech. 45: 2256–2263, 2012). This study tests if HiFiVS simulation can recapitulate real-life FD implantation. We deployed two identical FDs (Pipeline Embolization Device) into phantoms of a wide-necked segmental aneurysm using a clinical push-pull technique with different delivery wire advancements. We then simulated these deployment processes using HiFiVS and compared results against experimental recording. Stepwise comparison shows that the simulations precisely reproduced the FD deployment processes recorded in vitro. The local metal coverage rate and pore density quantifications demonstrated that simulations reproduced detailed FD mesh geometry. These results provide validation of the HiFiVS technique, highlighting its unique capability of accurately representing stent intervention in silico.

Enhanced Aneurysmal Flow Diversion Using a Dynamic Push-Pull Technique: An Experimental and Modeling Study

“…Two polymer phantoms of the aneurysm were created by using the previous method. 2 The phantom was connected to a flow loop to reduce friction. Microscopic images from the lateral and base (facing the aneurysm neck from the parent vessel) views were obtained during and after FD implantation for mesh analysis.…”

“…We used our previously described, finite-element-analysis-based high-fidelity virtual-stenting technique 2,6 to recapitulate the detailed deployment process in silico to study FD flow modification by computational fluid dynamics. The high-fidelity virtual stenting workflow incorporated several simplifications: 1) The delivery wire functionality was provided by the distal capture coil (before releasing the distal end of the FD) and the pusher (after the distal release); 2) a pathway was specified to guide the distal capture coil, the microcatheter, and the pusher; and 3) the vascular wall was assumed rigid in FD-vessel interaction.…”

“…A bench top study showed that an FD can form varied mesh densities through longitudinal compression, 1 consistent with our recent findings. 2 Meanwhile, there are concerns with using FDs in perforator-rich territories due to the likely occlusion of small vessel ostia. While increased mesh density at the aneurysm orifice may help aneurysmal flow reduction, it would be beneficial for the mesh density to be reducible in perforator-rich regions to preserve the perforators and branch vessels.…”

“…A follow-up study validated it through FD deployment in a fusiform phantom, 2 where DPPT was used on 2 FDs in 2 identical fusiform (basilar artery) aneurysm phantoms for differential mesh densities. We did not verify the posttreatment hemodynamic changes and did not investigate sidewall aneurysm morphology.…”

Editorial: Flow diverters: one device does not fit all

“…The main purpose of this study was to demonstrate that the high-fidelity virtual stenting (HiFiVS) modeling of FD deployment enables quantitative hemodynamic characterization of complex intracranial aneurysm cases. Through a series of earlier studies, we have developed this finite-element method-based HiFiVS technique 2,3 to simulate in silico the mechanical process of implanting FDs and we have investigated hemodynamic modifications by different FD delivery strategies. 4,6 However, the cases used in these virtual experiments were not treated by FDs in real life.…”