Takeaway
Similar underlying pathological processes, namely abnormal periventricular and cortical magnetization transfer ratio (MTR) gradients, occur in both primary- and secondary progressive multiple sclerosis (MS).
Why this matters
Cortical and periventricular MTR gradients may differ in primary progressive MS (PPMS) and secondary progressive MS (SPMS) depending on the presence of lymphoid follicles that are implicated in meningeal inflammation.