High-fidelity, high-isotropic-resolution diffusion imaging through gSlider acquisition with $B_1^{+}$ and T₁ corrections and integrated ΔB₀ /Rx shim array

Purpose: $B_1^{+}$ and T₁ corrections and dynamic multicoil shimming approaches were proposed to improve the fidelity of high-isotropic-resolution generalized slice-dithered enhanced resolution (gSlider) diffusion imaging.

Methods: An extended reconstruction incorporating $B_1^{+}$ inhomogeneity and T₁ recovery information was developed to mitigate slab-boundary artifacts in short-repetition time (TR) gSlider acquisitions. Slab-by-slab dynamic B₀ shimming using a multicoil integrated ΔB₀ /Rx shim array and high in-plane acceleration (R_inplane = 4) achieved with virtual-coil GRAPPA were also incorporated into a 1-mm isotropic resolution gSlider acquisition/reconstruction framework to achieve a significant reduction in geometric distortion compared to single-shot echo planar imaging (EPI).

Results: The slab-boundary artifacts were alleviated by the proposed $B_1^{+}$ and T₁ corrections compared to the standard gSlider reconstruction pipeline for short-TR acquisitions. Dynamic shimming provided >50% reduction in geometric distortion compared to conventional global second-order shimming. One-millimeter isotropic resolution diffusion data show that the typically problematic temporal and frontal lobes of the brain can be imaged with high geometric fidelity using dynamic shimming.

Conclusions: The proposed $B_1^{+}$ and T₁ corrections and local-field control substantially improved the fidelity of high-isotropic-resolution diffusion imaging, with reduced slab-boundary artifacts and geometric distortion compared to conventional gSlider acquisition and reconstruction. This enabled high-fidelity whole-brain 1-mm isotropic diffusion imaging with 64 diffusion directions in 20 min using a 3T clinical scanner.