Hemodynamic Characteristic Analysis of Aneurysm Wall Enhancement in Unruptured Middle Cerebral Artery Aneurysm

Abstract

Background and PurposeAneurysm wall enhancement (AWE) on vessel wall magnetic resonance imaging has been suggested as a marker of the unstable status of intracranial aneurysm (IA) and may predict IA rupture risk. However, the role of abnormal hemodynamics in unruptured IAs with AWE remains poorly understood. This study aimed to determine the association between abnormal hemodynamics and AWE in unruptured middle cerebral artery (MCA) aneurysms.MethodsA total of 28 patients with 32 bifurcation aneurysms of the middle cerebral artery>3mm in size were retrospectively selected for this study. Vessel wall magnetic resonance images were reviewed, and the AWE pattern of each aneurysm was classified as no AWE, partial AWE, and circumferential AWE. Computational fluid dynamics were used to calculate the hemodynamic variables of each aneurysm. Univariate and multivariate analyses investigated the association between AWE and hemodynamic variables.ResultsAWE was present in 13 aneurysms (40.6%), with 7 (21.9%) showing partial AWE and 6 (18.7%) showing circumferential AWE. Kruskal–Wallis H analysis revealed that hemodynamic variables including wall shear stress (WSS), oscillatory shear index, aneurysm pressure (AP), relative residence time, and low shear area (LSA) were significantly associated with AWE (p < 0.05). Further ordinal logistic regression analysis found that WSS was the only factor with a significant association with AWE (p = 0.048); similar trends were identified for LSA (p = 0.055) and AP (p = 0.058). Spearman's correlation analysis showed that AWE was negatively correlated with WSS (rs = −0.622, p < 0.001) and AP (rs = −0.535, p = 0.002) but positively correlated with LSA (rs = 0.774, p < 0.001).ConclusionLow wall shear stress, low aneurysm pressure, and increased low shear area were associated with aneurysm wall enhancement on vessel wall magnetic resonance imaging in unruptured cerebral aneurysms. These abnormal hemodynamic parameters may induce inflammation and cause aneurysm wall enhancement. However, the association between these parameters and their underlying pathological mechanisms requires further investigation.

Aneurysm wall enhancement, hemodynamics, and morphology of intracranial fusiform aneurysms

“…As mentioned earlier, low WSS may promote inflammatory cell infiltration, leading to pathological changes in the aneurysm wall. At the same time, increased vascular permeability may facilitate the penetration of contrast media into the aneurysm wall ( Zhong et al, 2022 ). Therefore, the enhanced regions showed the characteristics of low WSS.…”

“…The relationship between AWE and other hemodynamic parameters such as RRT, GON, and OSI is still controversial. It has been reported that circumferential wall enhancement is associated with long RRT ( Lv et al, 2020 ; Zhong et al, 2022 ). RRT, as an index of low or oscillatory WSS, reflects the residence time of blood near the vessel wall.…”

“…As is reported that different AWE patterns may be related to different morphological changes, with focal AWE related to secondary aneurysm formation and circumferential AWE related to whole sac dilation ( Hashimoto et al, 2021 ). Several studies have found a correlation between AWE patterns and hemodynamic characteristics, suggesting the possibility of aneurysm rupture ( Lv et al, 2020 ; Zhang et al, 2021 ; Zhong et al, 2022 ). Hemodynamics, which plays an important role in evaluating the risk of aneurysm progression, can be investigated through computational fluid dynamics (CFD) simulations.…”

“…Frontiers in Aging 08 frontiersin.org that circumferential wall enhancement is associated with long RRT (Lv et al, 2020;Zhong et al, 2022). RRT, as an index of low or oscillatory WSS, reflects the residence time of blood near the vessel wall.…”