  Purpose: This work aims to raise a novel design for navigator-free multiband
(MB) multishot uniform-density spiral (UDS) acquisition and reconstruction, and
to demonstrate its utility for high-efficiency, high-resolution diffusion
imaging. Theory and Methods: Our design focuses on the acquisition and
reconstruction of navigator-free MB multishot UDS diffusion imaging. For
acquisition, radiofrequency (RF) pulse encoding was employed to achieve
Controlled Aliasing in Parallel Imaging (CAIPI) in MB imaging. For
reconstruction, a new algorithm named slice-POCS-enhanced Inherent Correction
of phase Errors (slice-POCS-ICE) was proposed to simultaneously estimate
diffusion-weighted images and inter-shot phase variations for each slice. The
efficacy of the proposed methods was evaluated in both numerical simulation and
in vivo experiments. Results: In both numerical simulation and in vivo
experiments, slice-POCS-ICE estimated phase variations more precisely and
provided results with better image quality than other methods. The inter-shot
phase variations and MB slice aliasing artifacts were simultaneously resolved
using the proposed slice-POCS-ICE algorithm. Conclusion: The proposed
navigator-free MB multishot UDS acquisition and reconstruction method is an
effective solution for high-efficiency, high-resolution diffusion imaging.
