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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
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Long-Term Stability of Gradient Characteristics Warrants Model-Based Correction of Diffusion Weighting Bias
Yuxi Pang1, Dariya I Malyarenko1, Lisa J Wilmes2
1Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
Tomography (Ann Arbor, Mich.)
|February 24, 2022
Summary
This study demonstrates that magnetic resonance imaging (MRI) gradient characteristics are stable over time, enabling accurate model-based correction of diffusion weighting (DW) bias in apparent diffusion coefficient (ADC) measurements for multisite trials.
Area of Science:
- Medical Imaging
- Biophysics
- Magnetic Resonance Imaging
Background:
- Diffusion weighting (DW) bias in apparent diffusion coefficient (ADC) measurements can affect multisite imaging trials.
- Accurate ADC quantification is crucial for reliable results in clinical research.
Purpose of the Study:
- To assess the long-term stability of gradient characteristics in MRI scanners.
- To evaluate the feasibility of model-based correction for DW bias in ADC measurements.
- To investigate the impact of gradient nonlinearity (GNL) and other factors on ADC reproducibility.
Main Methods:
- Quarterly acquisition of single spin echo (SSE) and double spin echo (DSE) DWI on six MR scanners over two years using an ice-water phantom.
- Measurement of B0 maps and analysis of individual diffusion gradient channels with spatial offsets.
- Modeling of GNL using vendor specifications and quantification of deviations via root-mean-square differences (RMSD).
Main Results:
- Long-term stability of spatial ADC profiles was demonstrated, with temporal variations (RMSDTMP) close to measurement errors (~3%).
- GNL-induced bias varied up to 20%, while model deviations accounted for at most 6.5% of ADC reproducibility error.
- DSE DWI significantly reduced SSE RMSDEXP (7.5-11% to 2.5-4.8%), indicating eddy current contributions.
Conclusions:
- The long-term stability of spatial ADC profiles supports retrospective and prospective DW bias correction using system GNL models.
- Model-based correction for GNL is effective, but residual errors from eddy currents and shim gradients require independent correction.
- This approach enhances the reliability of ADC measurements in multisite MRI trials.
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