Computational fluid dynamics analysis of flow reduction induced by flow-diverting stents in intracranial aneurysms: a patient-unspecific hemodynamics change perspective

R. OUARED; I. LARRABIDE; O. BRINA; P. BOUILLOT; G. ERCEG; H. YILMAZ; K-O LOVBLAD; V. MENDES PEREIRA

Journal of NeuroInterventional Surgery

JNIS

Año: 2016

Background and purpose Flow-diverter stents (FDSs)have been used effectively to treat large neck andcomplex saccular aneurysms on the anterior carotidcirculation. Intra-aneurysmal flow reduction inducesprogressive aneurysm thrombosis in most patients.Understanding the degree of flow modification necessaryto induce complete aneurysm occlusion among patientswith considerable hemodynamics variability may beimportant for treatment planning.Materials and methods Patients with incidentalintracranial saccular aneurysms who underwent FDSendovascular procedures were included and studied for a12 months? follow-up period. We used computationalfluid dynamics on patient-specific geometries from 3Drotational angiography without and with virtual stentplacement and thus compared intra-aneurysmalhemodynamic problems. Receiver operating characteristicanalysis was used to estimate the stent:no-stentminimum hemodynamic ratio thresholds that significantly( p≤0.05) determined the condition necessary for long-term (12 months) aneurysm occlusion.Results We included 12 consecutive patients withsidewall aneurysms located in the internal carotid orvertebral artery. The measured porosity of the 12deployed virtual FDSs was 83±3% (mean±SD). Nineaneurysms were occluded during the 12 months? follow-up, whereas three were not. A significant ( p=0.05) areaunder the curve (AUC) was found for spatiotemporalmean velocity reduction in the aneurysms: AUC=0.889±0.113 (mean±SD) corresponding to a minimum velocityreduction threshold of 0.353 for occlusion to occur. The95% CI of the AUC was 0.66 to 1.00. The sensitivityand specificity of the method were ∼99% and ∼67%,respectively. For both wall shear stress and pressurereductions in aneurysms no thresholds could bedetermined: AUC=0.63±0.16 ( p=0.518) and 0.67±0.165 ( p=0.405), respectively.Conclusions For successful FDS treatment the post-stent average velocity in sidewall intracranial aneurysmsmust be reduced by at least one-third from the initialpre-stent conditions.