SNR-efficient distortion-free diffusion relaxometry imaging using accelerated echo-train shifted echo-planar time-resolving imaging (ACE-EPTI).

Autor: Dong Z; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.; Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts, USA., Wang F; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.; Harvard-MIT Health Sciences and Technology, MIT, Cambridge, Massachusetts, USA., Wald L; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.; Harvard-MIT Health Sciences and Technology, MIT, Cambridge, Massachusetts, USA., Setsompop K; Department of Radiology, Stanford University, Stanford, California, USA.; Department of Electrical Engineering, Stanford University, Stanford, California, USA.
Jazyk: angličtina
Zdroj: Magnetic resonance in medicine [Magn Reson Med] 2022 Jul; Vol. 88 (1), pp. 164-179. Date of Electronic Publication: 2022 Feb 28.
DOI: 10.1002/mrm.29198
Abstrakt: Purpose: To develop an efficient acquisition technique for distortion-free diffusion MRI and diffusion-relaxometry.
Methods: A new accelerated echo-train shifted echo-planar time-resolved imaging (ACE-EPTI) technique is developed to achieve high-SNR, distortion-free diffusion, and diffusion-relaxometry imaging. ACE-EPTI uses a newly designed variable density spatiotemporal encoding with self-navigators for phase correction, that allows for submillimeter in-plane resolution using only 3-shot. Moreover, an echo-train-shifted acquisition is developed to achieve minimal TE, together with an SNR-optimal readout length, leading to ∼30% improvement in SNR efficiency over single-shot EPI. To recover the highly accelerated data with high image quality, a tailored subspace image reconstruction framework is developed, that corrects for odd/even-echo phase difference, shot-to-shot phase variation, and the B 0 field changes because of field drift and eddy currents across different dynamics. After the phase-corrected subspace reconstruction, artifacts-free high-SNR diffusion images at multiple TEs are obtained with varying T 2 * weighting.
Results: Simulation, phantom, and in vivo experiments were performed, which validated the 3-shot spatiotemporal encoding provides accurate reconstruction at submillimeter resolution. The use of echo-train shifting and optimized readout length improves the SNR-efficiency by 27%-36% over single-shot EPI. The level of image distortion was also evaluated, which shows no noticeable susceptibility and eddy-current distortions in ACE-EPTI images that are common in EPI. The time-resolved acquisition of ACE-EPTI also provides multi-TE images for diffusion-relaxometry analysis.
Conclusion: ACE-EPTI was demonstrated to be an efficient and powerful technique for high-resolution diffusion imaging and diffusion-relaxometry, which provides high SNR, distortion- and blurring-free, and time-resolved multi-echo images by a fast 3-shot acquisition.
(© 2022 International Society for Magnetic Resonance in Medicine.)
Databáze: MEDLINE
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