Dataset Information

Romer-EPTI: Rotating-view motion-robust super-resolution EPTI for SNR-efficient distortion-free in-vivo mesoscale dMRI and microstructure imaging.

ABSTRACT:

Purpose

To overcome the major challenges in diffusion MRI acquisition, including low SNR, distortion/blurring, and motion vulnerability.

Methods

A novel Romer-EPTI technique is developed to provide high SNR, sharp spatial resolution, high motion-robustness, images free from distortion and slab-boundary artifacts, and simultaneous multi-TE imaging. It integrates a ROtating-view Motion-robust supEr-Resolution technique (Romer) with a distortion/blurring-free self-navigated EPTI encoding. Romer enhances SNR with high-motion robustness by employing a thick-slice acquisition with rotating-view encoding, and a motion-aware super-resolution reconstruction that incorporates motion, slice-profile and real-value diffusion. The in-plane encoding of the thick-slice volumes is performed using distortion/blurring-free EPTI readout, which further improves Romer's motion robustness by preventing detrimental blurring resulting from combination of inconsistent geometries caused by motion or eddy-current induced dynamic distortions. The Romer encoding, motion-aware reconstruction, together with T₂/T₂*-blurring-free EPTI readout enable effective reconstruction of the sharp spatial resolution. Furthermore, Romer-EPTI provides short TE and low SAR for 7T dMRI and high robustness to phase variations for high-b-value imaging.

Results

Using Romer-EPTI, we demonstrate distortion-free whole-brain mesoscale in-vivo dMRI at both 3T (500μm-iso) and 7T (485μm-iso) for the first time, with high SNR efficiency (e.g., 25×), and high image quality free from distortion and slab-boundary artifacts with minimal blurring. Motion experiments demonstrate the high motion-robustness of Romer-EPTI and its ability to recover sharp images in presence of subject motion. We also demonstrate its significant SNR gain and robustness in high b-value (b=5000s/mm²) and time-dependent dMRI.

Conclusion

Romer-EPTI significantly improves SNR, motion-robustness, and image quality of dMRI, providing a highly efficient acquisition for high-resolution dMRI and microstructure imaging.

SUBMITTER: Dong Z

PROVIDER: S-EPMC10862730 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature

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Publications

Romer-EPTI: rotating-view motion-robust super-resolution EPTI for SNR-efficient distortion-free in-vivo mesoscale dMRI and microstructure imaging.

Dong Zijing Z Reese Timothy G TG Lee Hong-Hsi HH Huang Susie Y SY Polimeni Jonathan R JR Wald Lawrence L LL Wang Fuyixue F

bioRxiv : the preprint server for biology 20240401

<h4>Purpose</h4>To overcome the major challenges in dMRI acquisition, including low SNR, distortion/blurring, and motion vulnerability.<h4>Methods</h4>A novel Romer-EPTI technique is developed to provide distortion-free dMRI with significant SNR gain, high motion-robustness, sharp spatial resolution, and simultaneous multi-TE imaging. It introduces a ROtating-view Motion-robust supEr-Resolution technique (Romer) combined with a distortion/blurring-free EPTI encoding. Romer enhances SNR by a simu ...[more]

PMID: 38352481

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Project description:PurposeTo overcome the major challenges in diffusion MRI (dMRI) acquisition, including limited SNR, distortion/blurring, and susceptibility to motion artifacts.Theory and methodsA novel Romer-EPTI technique is developed to achieve SNR-efficient acquisition while providing distortion-free imaging, minimal spatial blurring, high motion robustness, and simultaneous multi-TE imaging. It introduces a ROtating-view Motion-robust supEr-Resolution technique (Romer) combined with a distortion/blurring-free Echo Planar Time-resolved Imaging (EPTI) readout. Romer enhances SNR through simultaneous multi-thick-slice acquisition with rotating-view encoding, while providing high motion-robustness via a high-fidelity, motion-aware super-resolution reconstruction. Instead of EPI, the in-plane encoding is performed using EPTI readout to prevent geometric distortion, T2/T2*-blurring, and importantly, dynamic distortions that could introduce additional blurring/artifacts after super-resolution reconstruction due to combining volumes with inconsistent geometries. This further improves effective spatial resolution and motion robustness. Additional developments include strategies to address slab-boundary artifacts, achieve minimized TE and optimized readout for additional SNR gain, and increase robustness to strong phase variations at high b-values.ResultsUsing Romer-EPTI, we demonstrated distortion-free whole-brain mesoscale in-vivo dMRI at both 3T (500-μm isotropic [iso] resolution) and 7T (485-μm iso resolution) for the first time. Motion experiments demonstrated the technique's motion robustness and its ability to obtain high-resolution diffusion images in the presence of subject motion. Romer-EPTI also demonstrated high SNR gain and robustness in high b-value (b = 5000 s/mm2) and time-dependent dMRI.ConclusionThe high SNR efficiency, improved image quality, and motion robustness of Romer-EPTI make it a highly efficient acquisition for high-resolution dMRI and microstructure imaging.

Project description:PurposeTo develop a motion estimation and correction method for motion-robust three-dimensional (3D) quantitative imaging with 3D-echo-planar time-resolved imaging.Theory and methodsThe 3D-echo-planar time-resolved imaging technique was designed with additional four-dimensional navigator acquisition (x-y-z-echoes) to achieve fast and motion-robust quantitative imaging of the human brain. The four-dimensional-navigator is inserted into the relaxation-recovery deadtime of the sequence in every pulse TR (∼2 s) to avoid extra scan time, and to provide continuous tracking of the 3D head motion and B0 -inhomogeneity changes. By using an optimized spatiotemporal encoding combined with a partial-Fourier scheme, the navigator acquires a large central k-t data block for accurate motion estimation using only four small-flip-angle excitations and readouts, resulting in negligible signal-recovery reduction to the 3D-echo-planar time-resolved imaging acquisition. By incorporating the estimated motion and B0 -inhomogeneity changes into the reconstruction, multi-contrast images can be recovered with reduced motion artifacts.ResultsSimulation shows the cost to the SNR efficiency from the added navigator acquisitions is <1%. Both simulation and in vivo retrospective experiments were conducted, that demonstrate the four-dimensional navigator provided accurate estimation of the 3D motion and B0 -inhomogeneity changes, allowing effective reduction of image artifacts in quantitative maps. Finally, in vivo prospective undersampling acquisition was performed with and without head motion, in which the motion corrupted data after correction show close image quality and consistent quantifications to the motion-free scan, providing reliable quantitative measurements even with head motion.ConclusionThe proposed four-dimensional navigator acquisition provides reliable tracking of the head motion and B0 change with negligible SNR cost, equips the 3D-echo-planar time-resolved imaging technique for motion-robust and efficient quantitative imaging.