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Updated: Aug 19, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Short-term accrual of gray matter pathology in patients with progressive multiple sclerosis: an in vivo study using
Marco Rovaris1, Antonio Gallo, Paola Valsasina
1Neuroimaging Research Unit, Scientific Institute and University Ospedale San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
Abstract:
The mechanisms underlying the progressive course of multiple sclerosis (MS) are not fully understood yet. Since diffusion tensor (DT) MRI can provide quantitative estimates of both MRI-visible and MRI-occult brain damage related to MS, the present study investigated the value of DT MRI-derived measures for the assessment of the short-term accumulation of white and gray matter (GM) pathology in patients with primary progressive (PP) and secondary progressive (SP) MS. Fifty-four patients with PPMS and 22 with SPMS were studied at baseline and after a mean follow-up of 15 months. Dual-echo, T1-weighted, and DT MRI scans of the brain were acquired on both occasions. Total lesion volumes (TLV) and percentage brain volume changes (PBVC) were computed. Mean diffusivity (MD) and fractional anisotropy (FA) maps of the normal-appearing white (NAWM) and gray matter (NAGM) were produced, and histogram analysis was performed. In both patient groups, a significant increase of average lesion MD (P = 0.01) and of average NAGM MD (P = 0.007) was found at follow-up. No significant differences between PPMS and SPMS patient groups were found for the on-study changes of any MRI-derived measure. No significant correlations were found between the percentage changes of DT MRI-derived measures and those of TLV and PBVC. No significant changes of DT MRI-derived measures were observed in age-matched healthy controls over the same study period. Over a 1-year period of follow-up, DT MRI can detect tissue changes beyond the resolution of conventional MRI in the NAGM of patients with progressive MS. The accumulation of DT MRI-detectable gray matter damage does not seem to merely depend upon the concomitant increase of T2-visible lesion load and the reduction of brain volume. These observations suggest that progressive NAGM damage might yet be an additional factor leading to the accumulation of disability in progressive MS.
Insights
Diffusion tensor MRI detects subtle gray matter damage in progressive multiple sclerosis (MS) over 15 months. This damage accumulation is independent of lesion load and brain volume changes, suggesting it contributes to disability progression.
Area of Science:
- Neuroimaging
- Neurology
- Radiology
Background:
- The progression mechanisms in multiple sclerosis (MS) remain unclear.
- Diffusion tensor (DT) MRI offers quantitative insights into both visible and hidden brain damage in MS.
Purpose of the Study:
- To evaluate DT MRI measures for assessing short-term white and gray matter pathology in primary progressive MS (PPMS) and secondary progressive MS (SPMS).
Main Methods:
- Fifty-four PPMS and 22 SPMS patients underwent baseline and 15-month follow-up DT MRI scans.
- Analysis included lesion volumes, brain volume changes, and histogram analysis of mean diffusivity (MD) and fractional anisotropy (FA) in normal-appearing white and gray matter (NAWM/NAGM).
Main Results:
- Both PPMS and SPMS groups showed significant increases in average lesion MD and NAGM MD at follow-up.
- No significant differences in DT MRI measure changes were observed between PPMS and SPMS groups.
- Changes in DT MRI measures did not correlate with total lesion volume or percentage brain volume changes.
- Healthy controls showed no significant changes in DT MRI measures over the same period.
Conclusions:
- DT MRI detects progressive gray matter damage in MS beyond conventional MRI resolution within a year.
- This gray matter damage accumulation appears independent of lesion load and brain volume reduction.
- Progressive gray matter damage may be a key factor in disability accumulation in progressive MS.
