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Updated: Sep 8, 2025
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Test-retest and repositioning effects of white matter microstructure measurements in selected white matter tracts
Chaitali Anand1, Andreas M Brandmaier2,3,4, Jonathan Lynn5
1Department of Radiology, University of California, San Francisco, CA, USA.
Abstract:
We used intra-class effect decomposition (ICED) to evaluate the reliability of myelin water fraction (MWF) and geometric mean T2 relaxation time (geomT2IEW) estimated from a multi-echo MRI sequence. Our evaluation addressed test-retest reliability, with and without participant re-positioning, for seven commonly assessed white matter tracts: anterior and posterior limbs of the internal capsule, dorsal and ventral branches of the cingulum, the inferior fronto-occipital fasciculus, the superior longitudinal fasciculus, and the fornix in 20 healthy adults. We acquired two back-to-back scans in a single session, and a third after a break and repositioning the participant in the scanner. For both indices and for all white matter tracts assessed, reliability for an immediate retest, and after the participant's repositioning in the scanner was high. Variance partitioning revealed that in addition to measurement noise, which was significant in all regions, repositioning contributed to unreliability mainly in longer association fibers. Hemispheric location did not significantly contribute to unreliability in any region of interest (ROI). Thus, despite non-negligible error of measurement, for all ROIs, MWF and geomT2IEW have good test-retest reliability, regardless of the hemispheric location and are, therefore, suitable for longitudinal investigations in healthy adults.
Insights
Myelin water fraction (MWF) and geometric mean T2 relaxation time (geomT2IEW) show high test-retest reliability in white matter tracts. These MRI measures are reliable for longitudinal studies in healthy adults, even after repositioning.
Area of Science:
- Neuroimaging
- Quantitative MRI
- White Matter Tract Analysis
Background:
- Myelin water fraction (MWF) and geometric mean T2 relaxation time (geomT2IEW) are key quantitative MRI metrics.
- Assessing the reliability of these metrics is crucial for longitudinal studies.
- Intra-class effect decomposition (ICED) provides a robust method for reliability analysis.
Purpose of the Study:
- To evaluate the test-retest reliability of MWF and geomT2IEW using ICED.
- To assess reliability with and without participant repositioning.
- To investigate reliability across seven major white matter tracts in healthy adults.
Main Methods:
- Multi-echo MRI sequence used for data acquisition.
- Intra-class effect decomposition (ICED) applied for reliability analysis.
- Test-retest reliability assessed across immediate retest and repositioned scans in 20 healthy adults.
Main Results:
- High test-retest reliability observed for both MWF and geomT2IEW across all assessed white matter tracts.
- Repositioning contributed to unreliability primarily in longer association fibers, alongside measurement noise.
- Hemispheric location did not significantly impact the reliability of these metrics.
Conclusions:
- MWF and geomT2IEW demonstrate good test-retest reliability in healthy adults, suitable for longitudinal studies.
- The reliability is maintained irrespective of hemispheric location.
- Despite measurement noise, these quantitative MRI metrics are dependable for tracking white matter changes over time.
