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Background: It is estimated that 25-50\% of cerebral aneurysm rupture cases end up with the patient death, while around 50\% of survivors is left with permanent brain damage. Thus, it is extremely important to secure the aneurysm before it ruptures. Each endovascular treatment procedure can be carried out with varied implantable devices and the final choice of the treatment method is done by the neurosurgeon, based on his experience. The main objective of this research was to evaluate blood flow changes resulting from applying varied treatment options for the particular patient with the use of computational fluid dynamics (CFD) tools.
Methods: The patient-specific model of the cerebral aneurysm with afferent and efferent arteries was reconstructed based on biomedical imaging data. Then, idealized perforating vessels were added to the 3D model to mimic the presence of the real small-caliber vessels. Then, the authors performed virtual stenting with Flow Diverters manufactured by different companies (P64, PED, Surpass Streamline and Evolve) and virtual stent-assisted coiling with varied coil-packing density (0, 10, 15, 20, 25, and 30\%). Finally, transient simulation of the pulsatile flow were carried out, utilizing the Immersed Solid Method to model the presence of the particular stent.
Results: We noted significant changes in velocity- and viscosity-related parameters, as well as pressure and wall shear stress (WSS) magnitudes. Additionally, stent/coils presence resulted in more uniform pressure distribution at the aneurysm wall. Furthermore, a drastic reduction in the blood supply to the perforators covered by the stent wirebraid was observed. This confirms the statement that small-caliber vessels cannot be neglected while analyzing an influence of the stent on the overall flow hemodynamics.
Conclusions: Numerical analyses proved that magnitude of the changes in all hemodynamic parameters is strictly related to the topology of the stent wirebraid and coil packing density. Thus, this suggests that CFD tools can provide valuable information during selection of the most optimal treatment method for particular patient.
