Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms

Abstract

ObjectiveThis study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD).MethodA total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s.ResultFollow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01–1.11; P = 0.016).ConclusionThe study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

Numerical simulation techniques to predict aneurysm recanalization after coil embolization and their problems

“…where D p is the average particle diameter and κ is the porosity. The methods of Kozeny Carman's equation (K perm = ϕ 3 /cS 2 (where ϕ is the porosity of the medium, S is the specific surface area of coils, and c is the Kozeny coefficient)), and the rule of thumb of Jackson and James has been used in determining coefficients [10,[17][18][19]. When determining these coefficients, adjustments such as changing the size of the particles to be equivalent to the coil diameter or determining the porosity from the embolization rate were made, to make the model realistic.…”

“…There have been many reports on the recanalization factors of aneurysms using the coil modeling methods described above [6][7][8][9][10][11][12]. Studies investigating the hemodynamic aspects of recanalization of aneurysms after coil embolization from CFD analysis of both recanalized cases and stable cases has been conducted since around 2011.…”

“…Due to the improvement of computational technology and improvement of image resolution from the development of diagnostic imaging equipment such as computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA), an increasing amount of blood flow analysis using computational fluid dynamics (CFD) based on medical images have been performed [3][4][5]. This technique has also been introduced to investigate aneurysm recanalization, and multiple studies have been conducted so far [6][7][8][9][10][11][12]. CFD analysis were conducted on cases where coil embolization were performed, and it has been suggested that recanalization may be predicted by derived hemodynamic factors [8,10,12].…”

“…This technique has also been introduced to investigate aneurysm recanalization, and multiple studies have been conducted so far [6][7][8][9][10][11][12]. CFD analysis were conducted on cases where coil embolization were performed, and it has been suggested that recanalization may be predicted by derived hemodynamic factors [8,10,12]. The method in which the coil is modeled and deployed in an aneurysm is a major issue when performing CFD analysis to predict recanalization.…”

Using CFD Simulation and Porous Medium Analogy to Assess Cerebral Aneurysm Hemodynamics after Endovascular Embolization

“…In this study, porous media model is used to simulate the coiled aneurysm. In literature, porous medium has been implemented to model aneurysm coiling [10,11] and to model aneurysm diverting stent [12][13][14]. The current CFD study utilized the porous media parameters to assess the effect of coil parameters, mainly coil diameter and coil compactness, on the blood hemodynamics.…”