Diffusion-prepared 3D gradient spin-echo sequence for improved oscillating gradient diffusion MRI

Dan Wu, Dapeng Liu, Yi Cheng Hsu, Haotian Li, Yi Sun, Qin Qin, Yi Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: Oscillating gradient (OG) enables the access of short diffusion times for time-dependent diffusion MRI (dMRI); however, it poses several technical challenges for clinical use. This study proposes a 3D oscillating gradient–prepared gradient spin-echo (OGprep-GRASE) sequence to improve SNR and shorten acquisition time for OG dMRI on clinical scanners. Methods: The 3D OGprep-GRASE sequence consisted of global saturation, diffusion encoding, fat saturation, and GRASE readout modules. Multiplexed sensitivity-encoding reconstruction was used to correct the phase errors between multiple shots. We compared the scan time and SNR of the proposed sequence and the conventional 2D-EPI sequence for OG dMRI at 30-90-mm slice coverage. We also examined the time-dependent diffusivity changes with OG dMRI acquired at frequencies of 50 Hz and 25 Hz and pulsed-gradient dMRI at diffusion times of 30 ms and 60 ms. Results: The OGprep-GRASE sequence reduced the scan time by a factor of 1.38, and increased the SNR by 1.74-2.27 times compared with 2D EPI for relatively thick slice coverage (60-90 mm). The SNR gain led to improved diffusion-tensor reconstruction in the multishot protocols. Image distortion in 2D-EPI images was also reduced in GRASE images. Diffusivity measurements from the pulsed-gradient dMRI and OG dMRI showed clear diffusion-time dependency in the white matter and gray matter of the human brain, using both the GRASE and EPI sequences. Conclusion: The 3D OGprep-GRASE sequence improved scan time and SNR and reduced image distortion compared with the 2D multislice acquisition for OG dMRI on a 3T clinical system, which may facilitate the clinical translation of time-dependent dMRI.

Original languageEnglish (US)
Pages (from-to)78-88
Number of pages11
JournalMagnetic resonance in medicine
Volume85
Issue number1
DOIs
StatePublished - Jan 1 2021

Keywords

  • 3D-GRASE
  • diffusion-time dependency
  • oscillating gradient
  • signal-to-noise ratio | scan time

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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