Can Endovascular Treatment of Fusiform Intracranial Aneurysms Restore the Healthy Hemodynamic Environment?–A Virtual Pilot Study

Abstract

Numerous studies assess intracranial aneurysm rupture risk based on morphological and hemodynamic parameter analysis in addition to clinical information such as aneurysm localization, age, and sex. However, intracranial aneurysms mostly occur with a saccular shape located either lateral to the parent artery or at a bifurcation. In contrast, fusiform intracranial aneurysms (FIAs), i.e., aneurysms with a non-saccular, dilated form, occur in approximately 3–13% of all cases and therefore have not yet been as thoroughly studied. To improve the understanding of FIA hemodynamics, this pilot study contains morphological analyses and image-based blood flow simulations in three patient-specific cases. For a precise and realistic comparison to the pre-pathological state, each dilation was manually removed and the time-dependent blood flow simulations were repeated. Additionally, a validated fast virtual stenting approach was applied to evaluate the effect of virtual endovascular flow-diverter deployment focusing on relevant hemodynamic quantities. For two of the three patients, post-interventional information was available and included in the analysis. The results of this numerical pilot study indicate that complex flow structures, i.e., helical flow phenomena and the presence of high oscillating flow features, predominantly occur in FIAs with morphologically differing appearances. Due to the investigation of the individual healthy states, the original flow environment could be restored which serves as a reference for the virtual treatment target. It was shown that the realistic deployment led to a considerable stabilization of the individual hemodynamics in all cases. Furthermore, a quantification of the stent-induced therapy effect became feasible for the treating physician. The results of the morphological and hemodynamic analyses in this pilot study show that virtual stenting can be used in FIAs to quantify the effect of the planned endovascular treatment.

Fusiform versus Saccular Intracranial Aneurysms—Hemodynamic Evaluation of the Pre-Aneurysmal, Pathological, and Post-Interventional State

“…Deploying FDS as a minimally-invasive endovascular treatment of SIAs was established and the reduction of the flow into the SIA has been presented in many studies [ 6 , 41 , 42 ]. Fusiform-shaped IAs in the cerebrovascular circulation are as of yet not well studied, and knowledge about the flow field and treatment effect is still low [ 20 ]. The aim of this study was to analyze FIAs in comparison to SIAs focusing on the treatment with FDS.…”

“…Since FIAs occur only with a prevalence of approx. 3% of all IAs [ 15 ] and are rarely captured by medical imaging so far, this is nevertheless a progress in their investigation [ 20 , 47 ]. Third, regarding the virtual stenting and vessel reconstruction only one FDS version was virtually placed into the IAs neglecting the analysis of differences in porosity and no proof of the healthy vessel was available.…”

“…The goal is to bring the intra-aneurysmal flow to stasis by allowing a thrombus formation to occlude the aneurysm. The wall shear stress (WSS) along the scaffolding is restored to that of the original parent vessel prior to the pathological growth [ 19 ], while the goal of FIA treatment is identical, there are few studies to confirm that the hemodynamic outcomes are the same between FIAs and SIAs when treated with a FDS [ 20 , 21 , 22 , 23 ]. As found by Barletta et al, flow diversion seems to show most promising results concerning the treatment of FIAs [ 21 ].…”

“…As found by Barletta et al, flow diversion seems to show most promising results concerning the treatment of FIAs [ 21 ]. Saalfeld et al analyzed FIA’s hemodynamics qualitatively within pathological, healthy, and treated cases [ 20 ]. Lv et al investigated FIA morphology and stent deformation when applying virtual multiple treatment [ 24 ].…”