Porous Media Computational Fluid Dynamics and the Role of the First Coil in the Embolization of Ruptured Intracranial Aneurysms

Abstract

Background: The objective of our project was to identify a late recanalization predictor in ruptured intracranial aneurysms treated with coil embolization. This goal was achieved by means of a statistical analysis followed by a computational fluid dynamics (CFD) with porous media modelling approach. Porous media CFD simulated the hemodynamics within the aneurysmal dome after coiling. Methods: Firstly, a retrospective single center analysis of 66 aneurysmal subarachnoid hemorrhage patients was conducted. The authors assessed morphometric parameters, packing density, first coil volume packing density (1st VPD) and recanalization rate on digital subtraction angiograms (DSA). The effectiveness of initial endovascular treatment was visually determined using the modified Raymond–Roy classification directly after the embolization and in a 6- and 12-month follow-up DSA. In the next step, a comparison between porous media CFD analyses and our statistical results was performed. A geometry used during numerical simulations based on a patient-specific anatomy, where the aneurysm dome was modelled as a separate, porous domain. To evaluate hemodynamic changes, CFD was utilized for a control case (without any porosity) and for a wide range of porosities that resembled 1–30% of VPD. Numerical analyses were performed in Ansys CFX solver. Results: A multivariate analysis showed that 1st VPD affected the late recanalization rate (p < 0.001). Its value was significantly greater in all patients without recanalization (p < 0.001). Receiver operating characteristic curves governed by the univariate analysis showed that the model for late recanalization prediction based on 1st VPD (AUC 0.94 (95%CI: 0.86–1.00) is the most important predictor of late recanalization (p < 0.001). A cut-off point of 10.56% (sensitivity—0.722; specificity—0.979) was confirmed as optimal in a computational fluid dynamics analysis. The CFD results indicate that pressure at the aneurysm wall and residual flow volume (blood volume with mean fluid velocity > 0.01 m/s) within the aneurysmal dome tended to asymptotically decrease when VPD exceeded 10%. Conclusions: High 1st VPD decreases the late recanalization rate in ruptured intracranial aneurysms treated with coil embolization (according to our statistical results > 10.56%). We present an easy intraoperatively calculable predictor which has the potential to be used in clinical practice as a tip to improve clinical outcomes.

Onyx prevent the bleeding of ruptured aneurysms during interventional embolization

“…Consequently, small amounts of Onyx injected into an aneurysmal sac instantaneously coagulate within the aneurysm [21][22][23][24]24]. The decrease in blood ow velocity in the aneurysm-carrying artery accelerates intraaneurysmal retention of blood, thereby further minimizing the likelihood of Onyx escape.…”

Improving Computational Fluid Dynamics Simulations of Coiled Aneurysms Using Finite Element Modeling

“…Additionally, imaging of coils in vivo is limited by the imaging artifacts caused by the presence of the coils themselves. Due to this limitation the majority of CFD studies of coiled aneurysms have relied on naïve porous media assumptions(11, 12, 33, 34) that affect hemodynamic factors in unpredictable ways. (14) While predicting aneurysm recurrence is outside of the scope of this study, Damiano et al(35) demonstrated the potential for predicting aneurysm recurrence using CFD of virtually coiled aneurysms, representing the best attempt to relate post coiling hemodynamics to recurrence to date.…”

Hemodynamic study on the therapeutic effects of varying diameter embolic coils in the treatment of intracranial aneurysms

“…Karol et al utilized porous media computational fluid dynamics (CFD) to determine the reperfusion prediction factor for late-stage ruptured intracranial aneurysms treated with coil embolization. 13 Yasuyuki et al used porous media modeling to predict the recurrence of unruptured cerebral aneurysms after treatment. 14 However, the porous media approach assumes a uniform porosity as the volume density of the coil, which fails to accurately reflect the non-uniform distribution of the coils; ultimately, errors may be introduced in hemodynamic analysis.…”

“…Currently, the method of using porous media is commonly employed to simulate the post‐embolization state of an aneurysm in studies on coil embolization for aneurysms. Karol et al utilized porous media computational fluid dynamics (CFD) to determine the reperfusion prediction factor for late‐stage ruptured intracranial aneurysms treated with coil embolization 13 . Yasuyuki et al used porous media modeling to predict the recurrence of unruptured cerebral aneurysms after treatment 14 .…”