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Updated: Aug 23, 2026
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Redefinition of multiple sclerosis plaque size using diffusion tensor MRI
Susan M Kealey1, YoungJoo Kim, James M Provenzale
1Department of Neuroradiology, Duke University Medical Center, Box 3808, Erwin Rd., Durham, NC 27710, USA.
Objective:
We used diffusion tensor MRI to redefine the size of multiple sclerosis (MS) plaques on fractional anisotropy (FA) maps.
Materials And Methods:
Thirty-six white matter (WM) plaques were identified in 20 patients with MS. Plaque FA was measured by placing regions of interest (ROIs) on plaques on diffusion tensor images. We compared FA values in identical mirror-image ROIs placed on normal-appearing WM in the contralateral hemisphere. This comparison showed a mean decrease in FA of 41% in plaques, serving as the threshold for outlining abnormal regions in normal-appearing WM surrounding plaques. ROIs were placed around each plaque and FA values were compared with those in the mirror-image ROIs. Combined areas of perilesional normal-appearing WM with 40% or more FA reduction plus plaque were compared with the areas of abnormality on T2-weighted images using a paired Student's t test. A p value of 0.05 or less was considered significant.
Results:
Mean plaque area was 60 mm(2) (range, 15-103 mm(2)), mean plaque FA was 0.251 (range, 0.133-0.436), and mean FA of contralateral normal-appearing WM was 0.429 (range, 0.204-0.712). Applying a threshold of 40% FA reduction, mean combined area of abnormal WM (including plaque seen on T2-weighted sequences) was 87 mm(2) (range, 30-251 mm(2)) or 145% of the mean plaque area that was seen on T2-weighted images (p < 0.001).
Conclusion:
Using an operator-defined threshold of abnormal FA values based on plaque anisotropy characteristics, we saw a statistically significant increase in plaque size.
Insights
Diffusion tensor MRI redefined multiple sclerosis (MS) plaque size using fractional anisotropy (FA) maps. This method revealed significantly larger MS lesion volumes than previously identified on T2-weighted images.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- Multiple sclerosis (MS) is a chronic demyelinating disease affecting the central nervous system.
- Accurate assessment of lesion burden is crucial for understanding MS progression and treatment efficacy.
- Current methods may underestimate the full extent of MS lesions.
Purpose of the Study:
- To utilize diffusion tensor imaging (DTI) and fractional anisotropy (FA) maps to redefine the size of MS plaques.
- To compare lesion size determined by DTI-FA with conventional T2-weighted imaging.
Main Methods:
- Diffusion tensor MRI was used to analyze 36 white matter (WM) plaques in 20 MS patients.
- Regions of interest (ROIs) were placed on plaques and contralateral normal-appearing WM to measure FA.
- A 40% decrease in FA was used as a threshold to define abnormal perilesional WM, combined with the plaque itself.
Main Results:
- Mean plaque area on T2-weighted images was 60 mm².
- The DTI-FA method identified a combined abnormal WM area of 87 mm², which was 145% larger than the mean plaque area seen on T2-weighted images (p < 0.001).
- A mean FA decrease of 41% was observed in plaques compared to normal-appearing WM.
Conclusions:
- DTI-FA analysis provides a statistically significant increase in the measured size of MS plaques.
- This advanced imaging technique redefines MS lesion volume, potentially offering a more comprehensive measure of disease burden.
- Operator-defined FA thresholds can enhance the delineation of MS lesion extent.
