Stent-induced vessel deformation after intracranial aneurysm treatment - A hemodynamic pilot study

Background Stent-assisted coiling has become an important treatment option for intracranial aneurysms. However, studies have shown that this procedure can lead to the deformation of the local vasculature. Its effect on intra-aneurysmal hemodynamics still remains unclear. Methods: Pre- and post-interventional image data of three representative middle cerebral artery aneurysms are considered in this study. This includes virtually deployed stents and coils. To evaluate the proportional effect of a) vessel deformation, b) stent deployment, and c) coil placement, 24 unsteady blood flow simulations were carried out focusing on the separated effects related to intra-aneurysmal hemodynamics. Four flow parameters (velocity within the aneurysm sac, aneurysm neck inflow rate, inflow concentration index, and ostium inflow area) and four shear parameters (wall shear stress, normalized wall shear stress, shear concentration index, and high shear area) were quantified. Results: All of the considered flow and shear parameters, except for the shear concentration index, were clearly reduced due to treatment. Coiling and stenting caused a distinct and smaller neck inflow rate, respectively, while the impact of deformation was inconsistent among the aneurysms. Overall, coiling appears to have the strongest impact on local hemodynamics. Conclusion: Stent-induced vessel deformation has a clear impact on intra-aneurysmal hemodynamics. This effect is neglected by the majority of previous studies, which consider the pre-interventional state for investigating the relation of stents and hemodynamics. The findings of this pilot study suggest that while stent-assisted coiling can lead to an improved hemodynamic situation, undesired flow conditions may occur in response to treatment.