Beyond EPI: exploring EPTI as a new readout technique

Fuyixue Wang¹
¹A. A. Martinos Center for Biomedical Imaging, United States

Synopsis

Keywords: Image acquisition: Sequences

Echo Planar Time-resolved Imaging (EPTI) is a novel readout technique that addresses the limitations of EPI such as distortion and T2/T2* blurring by time-resolving across the EPI readout, while providing additional capability including multi-contrast multi-echo imaging. EPTI was initially introduced as a multi-shot technique highly suitable for high spatial resolution applications, and recent developments have also enabled single-shot EPTI acquisition to achieve high temporal resolution comparable to single-shot EPI, making it highly efficient for dynamic imaging applications as well. This talk will review EPTI-related techniques, the recent developments, and their applications in diffusion MRI, functional MRI,and multi-parametric quantitative imaging.

Abstract

EPTI is a novel readout technique that addresses the limitations of EPI such as distortion and T2/T2* blurring, while providing additional benefits like multi-contrast multi-echo imaging. It recognizes the strong spatiotemporal data correlation within the continuous readout and efficiently encodes in a spatiotemporal domain, which allows it to replace the conventional EPI image formation and resolve multi-echo images free from artifacts associated with the accumulated imperfections. This turns a liability—the evolution of the MR signal with time, which yields distortion/blurring—into an asset, providing benefits and unique features—distortion- and blurring-free, multi-echo images with a wide range of TEs, and high readout efficiency.

EPTI was initially introduced as a multi-shot technique highly suitable for high spatial resolution applications, and recent developments have also enabled single-shot EPTI acquisition to achieve high temporal resolution comparable to single-shot EPI, highly useful for dynamic imaging applications as well. Furthermore, moving from 2D to 3D EPTI encoding has shown promise in enhancing its acceleration capabilities. This talk will review EPTI-related techniques, recent developments, and their applications in diffusion MRI, functional imaging, and multi-parametric mapping.

Acknowledgements

NIH NINDS BRAIN Initiative (U24-NS129893).

References

1. Wang F, Dong Z, Reese TG, Bilgic B, Katherine Manhard M, Chen J, Polimeni JR, Wald LL, Setsompop K. Echo planar time-resolved imaging (EPTI). Magn Reson Med. 2019 Jun;81(6):3599-3615.

2. Dong Z, Wang F, Reese TG, Bilgic B, Setsompop K. Echo planar time-resolved imaging with subspace reconstruction and optimized spatiotemporal encoding. Magn Reson Med. 2020 Nov;84(5):2442-2455.

3. Dong Z, Wald LL, Polimeni JR, Wang F. Single-shot Echo Planar Time‐resolved Imaging for multi-echo functional MRI and distortion-free diffusion imaging. bioRxiv. 2024:2024.01.24.577002. doi: 10.1101/2024.01.24.577002.

4. Dong Z, Reese TG, Lee H-H, Huang SY, Polimeni JR, Wald LL, Wang F. Romer-EPTI: Rotating-view motion-robust super-resolution EPTI for SNR-efficient distortion-free in-vivo mesoscale dMRI and microstructure imaging. bioRxiv (2024) doi: 10.1101/2024.01.26.577343.

5. Wang F, Dong Z, Reese TG, Rosen B, Wald LL, Setsompop K. 3D Echo Planar Time-resolved Imaging (3D-EPTI) for ultrafast multi-parametric quantitative MRI. Neuroimage. 2022 Apr 15;250:118963.

6. Wang F, Dong Z, Wald LL, Polimeni JR, Setsompop K. Simultaneous pure T2 and varying T2'-weighted BOLD fMRI using Echo Planar Time-resolved Imaging for mapping cortical-depth dependent responses. Neuroimage. 2021 Dec 15;245:118641.

7. Dong Z, Wang F, Wald L, Setsompop K. SNR-efficient distortion-free diffusion relaxometry imaging using accelerated echo-train shifted echo-planar time-resolving imaging (ACE-EPTI). Magn Reson Med. 2022 Jul;88(1):164-179.

8. Dong Z, Wang F, Setsompop K. Motion-corrected 3D-EPTI with efficient 4D navigator acquisition for fast and robust whole-brain quantitative imaging. Magn Reson Med. 2022 Sep;88(3):1112-1125.

9. Dong Z, Wang F, Chan KS, Reese TG, Bilgic B, Marques JP, Setsompop K. Variable flip angle echo planar time-resolved imaging (vFA-EPTI) for fast high-resolution gradient echo myelin water imaging. Neuroimage. 2021 May 15;232:117897.

10. Fair MJ, Wang F, Dong Z, Reese TG, Setsompop K. Propeller echo-planar time-resolved imaging with dynamic encoding (PEPTIDE). Magn Reson Med. 2020 Jun;83(6):2124-2137.

11. Dai E, Lee PK, Dong Z, Fu F, Setsompop K, McNab JA. Distortion-free diffusion imaging using self-navigated Cartesian Echo-planar time resolved acquisition and joint magnitude and phase constrained reconstruction. IEEE Transactions on Medical Imaging. 2021 Aug 12;41(1):63-74.

12. Fair MJ, Liao C, Manhard MK, Setsompop K. Diffusion‐PEPTIDE: Distortion‐and blurring‐free diffusion imaging with self‐navigated motion‐correction and relaxometry capabilities. Magnetic Resonance in Medicine. 2021 May;85(5):2417-33.

13. Nan Wang, Yannick WE Brackenier, Congyu Liao, Siddharth Srinivasan Iyer, Xiaozhi Cao, Justin Haldar, and Kawin Setsompop. Spherical Echo-Planar Time-Resolved Imaging (SEPTI) For 3D Highly-Accelerated, Distortion-Free, Time-Resolved Whole-Brain T2* Mapping. ISMRM 2023 p0119.

14. Bai H, Qiu Y, Dai K, Chen H, and Zhang Z. Ultrafast Multi-Parametric Quantitative MRI Using Multi-TR Echo-Planar Time-Resolved Imaging (Multi-TR-EPTI), ISMRM 2023 p0252.

15. Krishnamurthy LC, Krishnamurthy V, Wang F, Wald LL, and Calhoun VD. Data-driven analysis of echo planar time-resolved MRI suggests frequency-specific mechanisms of brain fluctuations with unique TE signatures. ISMRM 2023 p1275.

Proc. Intl. Soc. Mag. Reson. Med. 32 (2024)