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Quantitative diffusion measurements in focal multiple sclerosis lesions: correlations with appearance on TI-weighted
1Department of Radiology, Mount Sinai School of Medicine, One Gustave L. Levy PI., New York, NY 10029, USA.
Objective:
Relative hypointensity on T1-weighted MR imaging has been suggested as a putative disability marker. The purpose of our study was to determine if there are quantifiable diffusion differences among focal multiple sclerosis lesions that appear differently on conventional T1-weighted MR images. We hypothesized that markedly hypointense lesions on unenhanced T1-weighted images would have significantly increased diffusion compared with other lesions, and enhancing portions of lesions would have different diffusion compared with nonenhancing lesions.
Subjects And Methods:
Average apparent diffusion coefficient (ADC) was calculated for 107 lesions identified on T2-weighted images in 16 patients with multiple sclerosis and was compared with the ADC of normal white matter in 16 age- and sex-matched control subjects. Seventy-five nonenhancing lesions (29 isointense, 46 hypointense) and 32 enhancing lesions (6 isointense, 26 hypointense) were categorized on the basis of unenhanced T1-weighted MR imaging.
Results:
Hypointense and isointense nonenhancing lesions both showed significantly higher ADC than normal white matter (p < 0.0001). Hypointense nonenhancing lesions showed higher ADC values than isointense nonenhancing lesions (p < 0.0001). Diffusion in enhancing portions of enhancing lesions was decreased when compared with nonenhancing portions.
Conclusion:
Quantitative diffusion data from MR imaging differ among multiple sclerosis lesions that appear different from each other on T1-weighted images. These quantitative diffusion differences imply microstructural differences, which may prove useful in documenting irreversible disease.
Insights
Multiple sclerosis lesions with T1 hypointensity show increased diffusion, suggesting microstructural differences. These apparent diffusion coefficient (ADC) variations may indicate irreversible disease progression in multiple sclerosis patients.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- T1-hypointense lesions on MRI are potential markers for multiple sclerosis (MS) disability.
- Understanding lesion heterogeneity is crucial for MS progression assessment.
Purpose of the Study:
- To investigate quantifiable diffusion differences in multiple sclerosis lesions based on their appearance on T1-weighted MRI.
- To determine if markedly hypointense lesions exhibit increased diffusion compared to other lesion types.
Main Methods:
- Apparent diffusion coefficient (ADC) was calculated for 107 MS lesions in 16 patients.
- Lesions were categorized as enhancing/nonenhancing and isointense/hypointense on T1-weighted MRI.
- ADC values were compared between lesion types and normal white matter.
Main Results:
- Both hypointense and isointense nonenhancing lesions demonstrated significantly higher ADC than normal white matter.
- Hypointense nonenhancing lesions had higher ADC values than isointense nonenhancing lesions.
- Enhancing lesion portions showed decreased diffusion compared to nonenhancing portions.
Conclusions:
- Quantitative diffusion MRI reveals microstructural differences among multiple sclerosis lesions.
- These diffusion variations correlate with T1-weighted imaging characteristics.
- Diffusion data may aid in documenting irreversible multiple sclerosis pathology.