Increased aneurysm wall permeability colocalized with low wall shear stress in unruptured saccular intracranial aneurysm.

Abstract

Aneurysm wall permeability has recently emerged as an in vivo marker of aneurysm wall remodeling. We sought to study the spatial relationship between hemodynamic forces derived from 4D-flow MRI and aneurysm wall permeability by DCE-MRI in a region-based analysis of unruptured saccular intracranial aneurysms (IAs). We performed 4D-flow MRI and DCE-MRI on patients with unruptured IAs of ≥ 5mm to measure hemodynamic parameters, including wall shear stress (WSS), oscillatory shear index (OSI), WSS temporal (WSSGt) and spatial (WSSGs) gradient, and aneurysm wall permeability (Ktrans) in different sectors of aneurysm wall defined by evenly distributed radial lines emitted from the aneurysm center. The spatial association between Ktrans and hemodynamic parameters measured at the sector level was evaluated. Thirty-one patients were scanned. Ktrans not only varied between aneurysms but also demonstrated spatial heterogeneity within an aneurysm. Among all 159 sectors, higher Ktrans was associated with lower WSS, which was seen in both Spearman's correlation analysis (rho = -0.18, p = 0.025) and linear regression analysis using generalized estimating equation to account for correlations between multiple sectors of the same aneurysm (regression coefficient = -0.33, p = 0.006). Aneurysm wall permeability by DCE-MRI was shown to be spatially heterogenous in unruptured saccular IAs and associated with local WSS by 4D-flow MRI.