Clinically feasible NODDI characterization of XXXX using multiband EPI at 7  T.

@entity1 @entity11 @entity5
Recent technological progress in the multiband echo planer imaging (MB EPI) technique enables accelerated MR diffusion weighted imaging (DWI) and allows whole brain, multi-b-value diffusion imaging to be acquired within a clinically feasible time. However, its applications at 7  T have been limited due to B1 field inhomogeneity and increased susceptibility artifact. It is an ongoing debate whether DWI at 7  T can be performed properly in @entity1 , and a systematic SNR comparison for multiband spin-echo EPI between 3  T and 7  T has not been methodically studied. The goal of this study was to use MB EPI at 7  T in order to obtain 90-directional multi-shell DWI within a clinically feasible acquisition time for @entity1 with @entity11 . This study included an SNR comparison between 3  T and 7  T, and the application of B1 mapping and distortion correction procedures for reducing the impact of variations in B0 and B1. The optimized multiband sequence was applied in 20 @entity1 with @entity11 to generate both DTI and NODDI maps for comparison of values in @entity5 and normal appearing white matter (NAWM). Our SNR analysis showed that MB EPI at 7  T was comparable to that at 3  T, and the data quality acquired in @entity1 was clinically acceptable. NODDI maps provided unique contrast within the T2 lesion that was not seen in anatomical images or DTI maps. Such contrast may reflect the complexity of tissue compositions associated with disease progression and treatment effects. The ability to consistently obtain high quality diffusion data at 7  T will contribute towards the implementation of a comprehensive brain MRI examination at ultra-high field.
