In vivo MR imaging

All MR imaging was performed using a 3.0T MR scanner (Achieva TX, Philips, Best, The Netherlands) with a 32-channel head coil. First, a 3D black-blood T1-weighted volumetric isotropic turbo spin echo acquisition (T1-VISTA) sequence (12) was used to investigate IA size and wall conditions. The imaging parameters were TR/TE =800/21 ms, FOV =200×180×40 mm³, voxel size =0.6×0.6×0.6 mm³, echo train length (ETL) =30, 2 startup echoes, and number of averages =1. The variable flip angle scheme was set according to a previously reported study (16). Further, 4D flow MRI data was acquired by a free-breathing, peripheral pulse-gated, multi-shot turbo field echo sequence for hemodynamic parameters evaluation. The scan parameters were TR/TE =8.0/3.6 ms, FOV =160×160×30 mm³, voxel size =1×1×1 mm³, velocity encoding (VENC) =120 cm/s for all 3 directions, flip angle =20°, turbo factor=3, 4 startup echoes, and number of averages =1. Parallel imaging was applied to accelerate the acquisition for T1-VISTA and 4D flow, with a sensitivity encoding (SENSE) factor of 2 and 3 in a right-to-left direction, respectively.