Paramagnetic Rims Detect Failure of Early Lesion Repair in MS

In vivo detection, monitoring chronic inflammation, and repair/remyelination are all important in identifying biological targets and developments of new treatments in multiple sclerosis (MS).

At the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) 2016 Forum, Martina Absinta, MD, National Institutes of Health (NIH), and colleagues discussed the concept of characterizing early lesion evolution according to patterns of gadolinium enhancement — centripetally and centrifugally enhancing lesions

It is also important to use MRI to identify the pathologically described subset of chronic lesions that could have detrimental persistent or “smoldering” inflammation at the lesion edge and associated impairment of remyelination, which could directly contribute to disease progression.

The team studied 22 centripetally and 20 centrifugally enhancing lesions at 7T MRI in 17 MS cases. For each lesion, the team analyzed the pattern of initial enhancement and the temporal evolution of the paramagnetic rim, lesion volume, and T1 hypointensity over the first year.

The results showed a range of information. In the centripetal lesions, phase rim colocalized with initial contrast enhancement. In 12 of 22 lesions, the same phase rim persisted even after enhancement had resolved, but in 10 cases, the phase rim was fleeting.

Researchers concluded, “The persistence of a phase rim in lesions that shrink least and become more T1-hypointense over time suggests that the rim might mark failure of early lesion repair or irreversible tissue damage and hence serve as a useful clinical-trial outcome measure.”