Eects of Coil Conguration and Packing Density on Intra-aneurysmal Hemodynamics

H. MORALES; M. KIM; E. E. VIVAS; M.C. VILLA-URIOL; I. LARRABIDE; T. SOLA; L. GUIMARAENS; A. F. FRANGI

Houston

Conferencia; Live Interventional Neuroradiology Conference (LINC) in conjunction with Intracranial Stent Meeting (ICS) 2010; 2010

Texas Heart Institute

Background and Purpose: Nowadays there is a lack of information about the influence of the coil configuration, i.e. the arrangement of the coil, on intra-aneurysmal hemodynamics. This makes difficulties to elucidate the hemodynamic changes with in vivo studies due to the unpredictable distribution of the coil inside the aneurysm after treatment and the limitations of the image acquisition modalities. Nonetheless, computational fluid dynamics (CFD) arise as a promising alternative to investigate this issue and to support clinical treatment planning without affecting the patient. In this work, we evaluated how coil configuration might influence the intra-aneurysmal hemodynamics insofar as the coil packing density increases using CFD modeling.Method: Three patient-specific intracranial aneurysms from different location in the human brain vasculature were studied. Vascular models were obtained after 3DRA image segmentation. These models were virtually treated with a coiling method. Each aneurysm was treated with five different packing densities (from 5.6% to 32 %). For each packing density, three different coil configurations were modeled. Transient CFD simulations were carried out in the untreated and the treated models. Blood was considered as a Newtonian fluid in an incompressible laminar flow regime. A fully-developed velocity profile was imposed at the inlet of each model while a traction-free condition at the outlets was considered. For each CFD simulation, the intra-aneurysmal velocity reduction rate (IVRR), defined as the differences between the intra-aneurysmal velocity before and after coiling, divided by the velocity before coiling was calculated. The relative influence of coil configuration among packing densities was statistically examined.Results: CFD simulations showed that IVRR progressively increased, and the IVRR differences induced by coil configuration decreased as packing density increased. When the packing densities were near 30%, IVRR of case 1 reached 70%, case 2 around 65%, while in case 3 almost 90%. The variance of the IVRR induced by the coil configuration was significant (p<0.01) when the packing density was lower than 22.2% (case 2 was the critical one). No significant differences (p>0.01) of IVRR due to coil configuration were obtained for packing densities near 30% in all the cases.Conclusion: From the hemodynamic point of view, our findings suggest that the influence of coil configuration on aneurysm hemodynamics was no significant (p>0.01) when the coil packing density near 30%.