Local tissue damage assessed with statistical mapping analysis of brain magnetization transfer ratio: relationship with functional status of patients in the earliest stage of multiple sclerosis

Abstract

Background and purpose: In the early stage of Multiple Sclerosis (MS), conventional MR imaging parameters such as T2 lesion load fail to explain the clinical status of patients. In the present work, we aimed to determine the ability of magnification transfer imaging to better reflect the relationship between local tissue damage and functional status of MS patients.

Methods: We performed a comparative statistical mapping analysis on brain tissue magnetization transfer ratio (MTR) data measured in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) and 18 matched control subjects.

Results: In the patients with CISSMS, a pattern of significant low MTR values was observed in the white matter, corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right superior longitudinal fasciculus (SLF), right inferior longitudinal fasciculus, optica radiata, parietal white matter, right cingulum, gray matter, bilateral thalamus, bilateral caudate, right insula, and left Brodmann area (BA) 8. No correlation was found between local MTR decrease and Expanded Disability Status Scale score. Significant correlations between MTR and MS Functional Composite scores (Spearman rank test, P <.05) were observed in the left BA40, right SLF, right frontal white matter, splenium, and anterior corpus callosum. Local MTR values correlated with Paced Auditory Serial Addition Test scores in the left BA40, right BA4, right SLF, and splenium.

Conclusion: Statistical mapping analysis of brain MTR data provides valuable information on the relationship between the location of brain tissue damage and its functional impact in patients with MS, even in the earliest stage of the disease.

Fig 1.

Statistical mapping analysis. Patterns of significant MTR abnormalities are observed inside the corpus callosum, bilateral occipitofrontal fascicles, right fornix, right parietal white matter, external capsule, right SLF, right ILF, optica radiata, parietal white matter, right cingulum, bilateral thalamus, bilateral caudate, right insula, and the left BA8. A, Multiplanar images of MTR decrease observed in patients with CISSMS compared with control subjects. B, Transverse images of MTR decrease observed in patients with CISSMS compared with control subjects.

Fig 2.

In patients with CISSMS, significant correlations between MTR and TMTA scores (Spearman rank test, P < .05) are observed inside the bilateral BA4, bilateral BA3, right BA6, left BA8, left frontal white matter, left occipitofrontal fascicles (top row, left to right) and in the left frontal white matter, left occipitofrontal fascicles, body of corpus callosum, bilateral cingulum, bilateral BA40, right lateral sulcus, and right claustrum (bottom row, left to right).

Fig 3.

In patients with CISSMS, significant correlations between MTR and MSFC scores (Spearman rank test, P < .05) are observed inside right SLF (FLS), right frontal white matter (WM), projections of the anterior corpus callosum (CC), splenium, and left BA40 (left to right).

Fig 4.

In patients with CISSMS, significant correlations between MTR and PASAT scores (Spearman rank test, P < .05) are observed in the splenium, left BA40, right BA 4, and right SLF.