MRI Techniques Could Help Distinguish Between MS and Migraine
Thalamic Volume
Thalamic atrophy is common in the early stages of relapsing-remitting MS. The thalamus also is implicated in migraine. Although studies have examined volumetric brain changes in migraine, none has examined thalamic volume specifically, said Dr. Solomon.
He and his colleagues used an automatic segmentation method to analyze thalamic volume in their cohort of 40 patients. Analysis of variance indicated that thalamic volume was significantly smaller in patients with MS, compared with patients without MS. When the researchers used a thalamic volume less than 0.0077 as a cutoff, the technique’s sensitivity and specificity for the diagnosis of MS were 0.75.
Recent data suggest that thalamic atrophy in MS does not result from thalamic lesions, but from diffuse white matter abnormalities. Like the central vein sign, thalamic atrophy may reflect MS pathophysiology and could be incorporated into MS diagnostic criteria, said Dr. Solomon.
Cortical Lesions
Autopsy and MRI studies have shown that cortical lesions are characteristic of MS, but MRI studies have suggested that migraineurs generally do not have cortical lesions. Although neurologists can see these lesions in vivo on 7-T MRI, 3-T MRI is not as sensitive and makes cortical lesion detection challenging.
In 2017, Nakamura and colleagues found that ratio maps of T1- and T2-weighted 3-T MRI, images that are acquired in routine clinical care for MS, could identify areas of cortical demyelination. Dr. Solomon and colleagues tested whether this method could distinguish MS from migraine. They defined a z score of less than 3 as an indication of low myelin density. When they examined the cohort of 40 patients, they were able to correlate areas with z scores below the cutoff with cortical lesions that were visible on conventional imaging. The technique accurately distinguished patients with MS from patients with migraine.
None of these emerging imaging techniques is 100% accurate. In the future, however, combining several of these techniques in conjunction with tests of blood biomarkers such as microRNA could accurately distinguish between MS and other disorders with high specificity and sensitivity, Dr. Solomon concluded.
—Erik Greb
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