Comparison of 7 T and 3 T vessel wall MRI for the evaluation of intracranial aneurysm wall.
OBJECTIVES
To compare the visibility of intracranial aneurysm wall and thickness quantification between 7 and 3 T vessel wall imaging and evaluate the association between aneurysm size and wall thickness.


METHODS
Twenty-nine patients with 29 unruptured intracranial aneurysms were prospectively recruited for 3D T1-weighted vessel wall MRI at both 3 T and 7 T with 0.53 mm (3 T) and 0.4 mm (7 T) 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).


RESULTS
Twenty-four patients with 24 aneurysms were included in this study. 7 T achieved significantly better aneurysm wall visibility than 3 T (3.6 ± 1.1 vs 2.7 ± 0.8, p = 0.003). AWT measured on 3 T and 7 T had a good correlation (averaged r = 0.63 ± 0.19). However, AWT on 3 T was 15% thicker than that on 7 T (0.52 ± 0.07 mm vs 0.45 ± 0.05 mm, p < 0.001). Wall sharpness on 7 T was 57% higher than that on 3 T (1.95 ± 0.32 mm-1 vs 1.24 ± 0.15 mm-1, p < 0.001). CRwall/lumen on 3 T and 7 T was comparable (p = 0.424). AWT on 7 T was positively correlated with aneurysm size (saccular: r = 0.58, q = 0.046; fusiform: r = 0.67, q = 0.049).


CONCLUSIONS
7 T provides better visualization of intracranial aneurysm wall with higher sharpness than 3 T. 3 T overestimates the wall thickness relative to 7 T. Aneurysm wall thickness is positively correlated with aneurysm size. 7 T MRI is a promising tool to evaluate aneurysm wall in vivo.


KEY POINTS
• 7 T provides better visualization of intracranial aneurysm wall with higher sharpness than 3 T. • 3 T overestimates the wall thickness comparing with 7 T. • Aneurysm wall thickness is positively correlated with aneurysm size.
['Feng|Junqiang|J|', 'Liu|Xinke|X|', 'Zhang|Zihao|Z|', 'Wu|Yue|Y|', 'Li|Zhixin|Z|', 'Zhang|Qiang|Q|', 'Jiang|Yuhua|Y|', 'You|Wei|W|', 'Liu|Peng|P|', 'Wang|Yan|Y|', 'Mossa-Basha|Mahmud|M|', 'Saloner|David|D|', 'Li|Youxiang|Y|http://orcid.org/0000-0002-3995-4106', 'Zhu|Chengcheng|C|']
MRI Intracranial aneurysm Wall thickness