Examine the relationship between lesion volume in deep grey matter (DGM) structures and cognition with 7T MRI in persons with MS.

Cognitive dysfunction is common in MS. Previous studies using 3T MRI have shown lesions involving grey matter, however, the relationship between cognitive function and DGM lesions has not been fully elucidated.

The Minimal Assessment of Cognitive Function in MS (MACFIMS) battery was administered within one month of 7T MRI scan in persons with MS. The following DGM structures were identified: thalamus, caudate, putamen, amygdala, hippocampus and cingulate gyrus. Lesions were counted and measured for total lesion volume. Pearson’s R was calculated for lesion volume compared to scores on individual MACFIMS test.

28 subjects (22 female) were enrolled, with a mean age and education of 38.3 (+/- 5.7) and 13.6 (+/- 2.1) years, respectively. Most (26, 92.9%) were diagnosed with RRMS. Disease duration was 7.4 (+/-5.5) years. Median EDSS was 1.75 (range 0-4.0). The majority (71.4%) were on a disease modifying treatment.

Lower California verbal learning test-II (CVLT2) immediate recall (IR), indicating lower performance, correlated with an increase in thalamic lesion size (R=-0.415; p=0.049) while lower Brief Visuospatial Memory Test, Revised (BVMTR) IR correlated with larger lesion volumes in the cingulate gyrus (R=-0.481; p=0.02). Lower Symbol Digit Modalities Test (SDMT) was significantly associated with higher lesion volume in the caudate (R=-0.575; p=0.004). When right and left sides of these structures were examined, lower CVLT-II IR was particularly associated with higher lesion volumes in the right thalamus (R=-0.451; p=0.031) and left amygdala (R=-0.431; p=0.04). Lower SDMT correlated with lesions in the right caudate (R=-0.442; p=0.35) and left amygdala (R=-0.430; p=0.40).

Using 7T MRI, lesions can be measured within the thalamus, cingulate gyrus, caudate and amygdala which correlate with lower scores of cognitive function in persons with MS.