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Published on: August 14, 2019
Inversion-Recovery-Prepared Oscillating Gradient Sequence Improves Diffusion-Time Dependency Measurements in the
Haotian Li1, Tao Zu1, Yi-Cheng Hsu2
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China.
Background:
Oscillating gradient diffusion MRI (dMRI) enables measurements at a short diffusion-time (td ), but it is challenging for clinical systems. Particularly, the low b-value and low resolution may give rise to cerebrospinal fluid (CSF) contamination.
Purpose:
To assess the effect of CSF partial volume on td -dMRI measurements and efficacy of inversion-recovery (IR) prepared oscillating and pulsed gradient dMRI sequence to improve td -dMRI measurements in the human brain.
Study Type:
Prospective.
Subjects:
Ten normal volunteers and six glioma patients.
Field Strength/Sequence:
A 3 T; three-dimensional (3D) IR-prepared oscillating gradient-prepared gradient spin-echo (GRASE) and two-dimensional (2D) IR-prepared oscillating gradient echo-planar imaging (EPI) sequences.
Assessment:
We assessed the td -dependent patterns of apparent diffusion coefficient (ADC) in several gray and white matter structures, including the hippocampal subfields (head, body, and tail), cortical gray matter, thalamus, and posterior white matter in normal volunteers. Pulsed gradient (0 Hz) and oscillating gradients at frequencies of 20 Hz, 40 Hz, and 60 Hz dMRI were acquired with GRASE and EPI sequences with or without the IR module. We also tested the td -dependency patterns in glioma patients using the EPI sequence with or without the IR module.
Statistical Tests:
The differences in ADC across the different td s were compared by one-way ANOVA followed by post hoc pairwise t-tests with Bonferroni correction.
Results:
In the healthy subjects, brain regions that were possibly contaminated by CSF signals, such as the hippocampus (head, body, and tail) and cortical gray matter, td -dependent ADC changes were only significant with the IR-prepared 2D and 3D sequences but not with the non-IR sequences. In brain glioblastomas patients, significantly higher td -dependence was observed in the tumor region with the IR module than that without IR (slope = 0.0196 μm2 /msec2 vs. 0.0034 μm2 /msec2 ).
Conclusion:
The IR-prepared sequence effectively suppressed the CSF partial volume effect and significantly improved the td -dependent measurements in the human brain.
Evidence Level:
1 TECHNICAL EFFICACY: Stage 1.
Insights
Inversion-recovery prepared diffusion MRI effectively reduces cerebrospinal fluid contamination, improving short diffusion-time measurements in the brain. This technique enhances accuracy for both healthy subjects and glioma patients.
Area of Science:
- Neuroimaging
- Diffusion MRI Physics
Background:
- Short diffusion-time (td) diffusion MRI (dMRI) offers advanced measurements but faces challenges in clinical settings.
- Cerebrospinal fluid (CSF) contamination is a significant issue in low b-value, low-resolution dMRI.
Purpose of the Study:
- To evaluate the impact of CSF partial volume on td-dMRI measurements.
- To assess the efficacy of inversion-recovery (IR) prepared oscillating and pulsed gradient dMRI sequences in improving these measurements.
Main Methods:
- Utilized 3T MRI with 3D IR-prepared oscillating gradient-prepared gradient spin-echo (GRASE) and 2D IR-prepared oscillating gradient echo-planar imaging (EPI) sequences.
- Assessed td-dependent apparent diffusion coefficient (ADC) patterns in normal volunteers and glioma patients with and without IR preparation.
Main Results:
- IR-prepared sequences significantly improved td-dependent ADC measurements in CSF-contaminated regions (hippocampus, cortex) in healthy subjects.
- Glioma patients showed significantly higher td-dependence in tumors with IR compared to non-IR sequences.
Conclusions:
- The IR-prepared sequence effectively mitigates CSF partial volume effects.
- This method significantly enhances the accuracy of td-dependent dMRI measurements in the human brain.
