Visualizing wall enhancement over time in unruptured intracranial aneurysms using 3D vessel wall imaging

Abstract

Background: Few studies directed at assessing the visualization of the walls of unruptured aneurysms have used higher-resolution 3D MRI vessel wall imaging. Prospective longitudinal studies are also needed to screen vessel wall changes in unruptured aneurysms.

Purpose: To compare the aneurysm wall visualization on pre- and post-3D isotropic T₁ -weighted Sampling Perfection with Application-optimized Contrasts by using different flip angle Evolutions (SPACE) images and to explore whether there is a change in wall enhancement at follow up.

Study type: Prospective.

Population: Twenty-nine patients with a total of 35 unruptured intracranial aneurysms.

Sequence: 3D T₁ -weighted pre- and postcontrast SPACE (0.5 mm isotropic) at 3.0T.

Assessment: The aneurysm wall visibility (0-5 scale) between pre- and postcontrast images as well as the wall enhancement (0-5 scale) between follow-up and baseline studies (6-30 months, average 12.7 months) were compared. Differences in wall visibility and enhancement were also investigated as a function of aneurysm diameter and location.

Statistical test: The Wilcoxon signed rank paired test was used to compare the wall visibility score between pre- and postcontrast SPACE images, as well as wall enhancement between follow-up and baseline. The Mann-Whitney and Kruskal-Wallis tests were used to investigate the enhancement difference between different diameters and locations.

Results: Postcontrast images had significantly higher wall visibility (P = 0.01). A wall enhancement score ≥2 was found in 71% of the aneurysms. Changes in levels of wall enhancement were found in 17% of the aneurysms at follow-up studies, but those changes were small. Wall visibility and enhancement scores of large aneurysms were significantly higher than small ones (P < 0.001).

Data conclusion: 3D T₁ -weighted higher resolution SPACE can be used to assess changes in enhancement at follow-up studies. Contrast SPACE image provides better aneurysm wall visibility and improves visualization of the aneurysm wall.

Level of evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:193-200.