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Updated: Aug 3, 2026
Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
High-fidelity mesoscale in-vivo diffusion MRI through gSlider-BUDA and circular EPI with S-LORAKS reconstruction
Congyu Liao1, Uten Yarach2, Xiaozhi Cao1
1Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
Purpose:
To develop a high-fidelity diffusion MRI acquisition and reconstruction framework with reduced echo-train-length for less T2* image blurring compared to typical highly accelerated echo-planar imaging (EPI) acquisitions at sub-millimeter isotropic resolution.
Methods:
We first proposed a circular-EPI trajectory with partial Fourier sampling on both the readout and phase-encoding directions to minimize the echo-train-length and echo time. We then utilized this trajectory in an interleaved two-shot EPI acquisition with reversed phase-encoding polarity, to aid in the correction of off-resonance-induced image distortions and provide complementary k-space coverage in the missing partial Fourier regions. Using model-based reconstruction with structured low-rank constraint and smooth phase prior, we corrected the shot-to-shot phase variations across the two shots and recover the missing k-space data. Finally, we combined the proposed acquisition/reconstruction framework with an SNR-efficient RF-encoded simultaneous multi-slab technique, termed gSlider, to achieve high-fidelity 720 µm and 500 µm isotropic resolution in-vivo diffusion MRI.
Results:
Both simulation and in-vivo results demonstrate the effectiveness of the proposed acquisition and reconstruction framework to provide distortion-corrected diffusion imaging at the mesoscale with markedly reduced T2*-blurring. The in-vivo results of 720 µm and 500 µm datasets show high-fidelity diffusion images with reduced image blurring and echo time using the proposed approaches.
Conclusions:
The proposed method provides high-quality distortion-corrected diffusion-weighted images with ∼40% reduction in the echo-train-length and T2* blurring at 500µm-isotropic-resolution compared to standard multi-shot EPI.
Insights
This study introduces a new diffusion MRI method reducing echo-train length for clearer images. The advanced acquisition and reconstruction framework achieves high-fidelity, distortion-corrected diffusion imaging with less blurring.
Area of Science:
- Magnetic Resonance Imaging
- Neuroimaging
- Biomedical Engineering
Background:
- Diffusion MRI (dMRI) is crucial for visualizing white matter microstructure.
- Echo-planar imaging (EPI) is fast but suffers from T2* blurring and distortions.
- Accelerated EPI techniques often exacerbate these issues, limiting resolution.
Purpose of the Study:
- To develop a high-fidelity dMRI acquisition and reconstruction framework.
- Reduce echo-train length (ETL) and echo time (TE) to minimize T2* blurring.
- Achieve sub-millimeter isotropic resolution with distortion correction.
Main Methods:
- Proposed a circular-EPI trajectory with partial Fourier sampling to shorten ETL and TE.
- Utilized interleaved two-shot EPI with reversed phase-encoding for distortion correction.
- Employed model-based reconstruction with low-rank and phase priors for k-space recovery.
- Integrated with simultaneous multi-slab (gSlider) technique for accelerated whole-brain coverage.
Main Results:
- Demonstrated effectiveness in simulations and in-vivo experiments.
- Achieved high-fidelity 720 µm and 500 µm isotropic resolution dMRI.
- Showcased markedly reduced T2* blurring and image distortions.
- Confirmed significant improvements compared to standard multi-shot EPI.
Conclusions:
- The developed framework provides high-quality, distortion-corrected dMRI.
- Achieved ~40% reduction in ETL and T2* blurring at 500 µm resolution.
- Enables clearer visualization of brain microstructure at high resolution.
