Do second-order motion-compensation gradients and spiral sampling suppress phase variations in DWI?

Motivation: Phase variation introduces complexity to multishot 2D or 3D DWI. Using second-order motion-compensation (MC2) gradients and peripheral pulse unit (PPU) trigger, single-slab whole-brain 3D EPI DWI shows promise. We aim to test whether stack of spiral(3D spiral) using MC2 avoid phase variation without trigger. Goal(s): To test the performance of motion-compensated 3D spiral imaging without trigger. Approach: We acquired whole-brain DWI data using motion-compensated 3D spiral with and without trigger, and collected 2D SMS EPI data for reference. Results: Without trigger, 3D spiral showed instable image quality using direction reconstruction, while with trigger, 3D spiral eliminated phase variation, resulting in better reconstruction. Impact: This study confirms the necessity of trigger in motion-compensated stack of spiral, as whole-brain single-slab DWI cannot be achieved without it.