  3D multi-slab acquisitions are an appealing approach for diffusion MRI
because they are compatible with the imaging regime delivering optimal SNR
efficiency. In conventional 3D multi-slab imaging, shot-to-shot phase
variations caused by motion pose challenges due to the use of multi-shot
k-space acquisition. Navigator acquisition after each imaging echo is typically
employed to correct phase variations, which prolongs scan time and increases
the specific absorption rate (SAR). The aim of this study is to develop a
highly efficient, self-navigated method to correct for phase variations in 3D
multi-slab diffusion MRI without explicitly acquiring navigators. The sampling
of each shot is carefully designed to intersect with the central kz plane of
each slab, and the multi-shot sampling is optimized for self-navigation
performance while retaining decent reconstruction quality. The central kz
intersections from all shots are jointly used to reconstruct a 2D phase map for
each shot using a structured low-rank constrained reconstruction that leverages
the redundancy in shot and coil dimensions. The phase maps are used to
eliminate the shot-to-shot phase inconsistency in the final 3D multi-shot
reconstruction. We demonstrate the method's efficacy using retrospective
simulations and prospectively acquired in-vivo experiments at 1.22 mm and 1.09
mm isotropic resolutions. Compared to conventional navigated 3D multi-slab
imaging, the proposed self-navigated method achieves comparable image quality
while shortening the scan time by 31.7% and improving the SNR efficiency by
15.5%. The proposed method produces comparable quality of DTI and white matter
tractography to conventional navigated 3D multi-slab acquisition with a much
shorter scan time.
