Phase stabilization with motion compensated diffusion weighted imaging

Abstract

AbstractPurposeDiffusion encoding gradient waveforms can impart intra‐voxel and inter‐voxel dephasing owing to bulk motion, limiting achievable signal‐to‐noise and complicating multishot acquisitions. In this study, we characterize improvements in phase consistency via gradient moment nulling of diffusion encoding waveforms.MethodsHealthy volunteers received neuro () and cardiac () MRI. Three gradient moment nulling levels were evaluated: compensation for position (), position + velocity (), and position + velocity + acceleration (). Three experiments were completed: (Exp‐1) Fixed Trigger Delay Neuro DWI; (Exp‐2) Mixed Trigger Delay Neuro DWI; and (Exp‐3) Fixed Trigger Delay Cardiac DWI. Significant differences () of the temporal phase SD between repeated acquisitions and the spatial phase gradient across a given image were assessed.Results moment nulling was a reference for all measures. In Exp‐1, temporal phase SD for diffusion encoding was significantly reduced with (35% of t‐tests) and (68% of t‐tests). The spatial phase gradient was reduced in 23% of t‐tests for and 2% of cases for . In Exp‐2, temporal phase SD significantly decreased with gradient moment nulling only for (83% of t‐tests), but spatial phase gradient significantly decreased with only (50% of t‐tests). In Exp‐3, gradient moment nulling significantly reduced temporal phase SD and spatial phase gradients (100% of t‐tests), resulting in less signal attenuation and more accurate ADCs.ConclusionWe characterized gradient moment nulling phase consistency for DWI. Using M1 for neuroimaging and M1 + M2 for cardiac imaging minimized temporal phase SDs and spatial phase gradients.