Phase stabilization with motion compensated diffusion weighted imaging

Ariel J Hannum; Tyler E Cork; Kawin Setsompop; Daniel B Ennis

doi:10.1002/mrm.30218

Phase stabilization with motion compensated diffusion weighted imaging

Magn Reson Med. 2024 Jul 12. doi: 10.1002/mrm.30218. Online ahead of print.

Authors

Ariel J Hannum^{1

2

3}, Tyler E Cork^{1

2

3}, Kawin Setsompop^{1

4}, Daniel B Ennis^{1

2}

Affiliations

¹ Department of Radiology, Stanford University, Stanford, California, USA.
² Division of Radiology, Veterans Administration Health Care System, Palo Alto, California, USA.
³ Department of Bioengineering, Stanford University, Stanford, California, USA.
⁴ Department of Electrical Engineering, Stanford University, Stanford, California, USA.

PMID: 38997801
DOI: 10.1002/mrm.30218

Abstract

Purpose: Diffusion 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.

Methods: Healthy volunteers received neuro ( $N = 10$ ) and cardiac ( $N = 10$ ) MRI. Three gradient moment nulling levels were evaluated: compensation for position ( $M_{0}$ ), position + velocity ( $M_{1}$ ), and position + velocity + acceleration ( $M_{1} + M_{2}$ ). 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 ( $p < 0.05$ ) of the temporal phase SD between repeated acquisitions and the spatial phase gradient across a given image were assessed.

Results: $M_{0}$ moment nulling was a reference for all measures. In Exp-1, temporal phase SD for $G_{z}$ diffusion encoding was significantly reduced with $M_{1}$ (35% of t-tests) and $M_{1} + M_{2}$ (68% of t-tests). The spatial phase gradient was reduced in 23% of t-tests for $M_{1}$ and 2% of cases for $M_{1} + M_{2}$ . In Exp-2, temporal phase SD significantly decreased with $M_{1} + M_{2}$ gradient moment nulling only for $G_{z}$ (83% of t-tests), but spatial phase gradient significantly decreased with only $M_{1}$ (50% of t-tests). In Exp-3, $M_{1} + M_{2}$ 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.

Conclusion: We 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.

Keywords: brain; cardiac; diffusion‐weighted imaging; motion‐compensation; phase.

Abstract

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