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Time-division multiplexing (TDM) sequence removes bias in T2 estimation and relaxation-diffusion measurements
Qiang Liu1,2, Borjan Gagoski3,4, Imam Ahmed Shaik1
1Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
Biorxiv : the Preprint Server for Biology
|June 19, 2024
Summary
Time-division multiplexing (TDM) MRI sequences offer reliable and accelerated relaxation-diffusion MRI (rdMRI) microstructure measurements, outperforming multi-echo (ME) sequences in accuracy and T2 estimation.
Area of Science:
- Magnetic Resonance Imaging
- Diffusion MRI
- Biomedical Engineering
Background:
- Accelerated MRI acquisition techniques are crucial for reducing scan times.
- Relaxation-diffusion MRI (rdMRI) provides insights into tissue microstructure.
- Comparing different accelerated acquisition sequences is essential for optimizing rdMRI.
Purpose of the Study:
- To compare the performance of multi-echo (ME) and time-division multiplexing (TDM) sequences for accelerated rdMRI.
- To evaluate the reliability of ME and TDM in estimating accurate rdMRI microstructure measures.
Main Methods:
- Implemented ME, TDM, and single-echo (SE) sequences with six echo times (TE) using Pulseq.
- Utilized single-band (SB-) and multi-band 2 (MB2-) acceleration factors.
- Quantified differences using normalized root mean squared error (NRMSE) on phantom and in-vivo data, assessing T2 estimates, REDIM, and MaxEnt-RDD.
Main Results:
- TDM performance closely matched the gold standard SE acquisition.
- ME sequences exhibited greater biases in image intensity and T2 estimation compared to SE and TDM.
- TDM provided comparable diffusion and relaxation parameters to SE, while ME showed significant biases.
Conclusions:
- TDM sequences provide more accurate relaxation-diffusion measurements than ME sequences.
- TDM enables accelerated rdMRI acquisition with a factor of 2 to 3 without compromising accuracy.
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