Comparison of 7T and 3T vessel wall MRI for the evaluation of intracranial aneurysm wall.

Abstract

To compare the visibility of intracranial aneurysm wall and thickness quantification between 7 and 3T vessel wall imaging and evaluate the association between aneurysm size and wall thickness. Twenty-nine patients with 29 unruptured intracranial aneurysms were prospectively recruited for 3D T1-weighted vessel wall MRI at both 3T and 7T with 0.53mm (3T) and 0.4mm (7T) isotropic resolution, respectively. Two neuroradiologists independently evaluated wall visibility (0-5 Likert scale), quantified the apparent wall thickness (AWT) using a semi-automated full-width-half-maximum method, calculated wall sharpness, and measured the wall-to-lumen contrast ratio (CRwall/lumen). Twenty-four patients with 24 aneurysms were included in this study. 7T achieved significantly better aneurysm wall visibility than 3T (3.6 ± 1.1 vs 2.7 ± 0.8, p = 0.003). AWT measured on 3T and 7T had a good correlation (averaged r = 0.63 ± 0.19). However, AWT on 3T was 15% thicker than that on 7T (0.52 ± 0.07mm vs 0.45 ± 0.05mm, p < 0.001). Wall sharpness on 7T was 57% higher than that on 3T (1.95 ± 0.32mm-1 vs 1.24 ± 0.15mm-1, p < 0.001). CRwall/lumen on 3T and 7T was comparable (p = 0.424). AWT on 7T was positively correlated with aneurysm size (saccular: r = 0.58, q = 0.046; fusiform: r = 0.67, q = 0.049). 7T provides better visualization of intracranial aneurysm wall with higher sharpness than 3T. 3T overestimates the wall thickness relative to 7T. Aneurysm wall thickness is positively correlated with aneurysm size. 7T MRI is a promising tool to evaluate aneurysm wall in vivo. • 7T provides better visualization of intracranial aneurysm wall with higher sharpness than 3T. • 3T overestimates the wall thickness comparing with 7T. • Aneurysm wall thickness is positively correlated with aneurysm size.