As I understand . . . it is the inflammatory process that makes them enhance and (not that it probably matters) the lesions can be new ones or older one's. They should be able to tell if they are net-new though, because they will have old scarring if they are expanding due to new inflammation.

http://www.pubmedcentral.nih.gov/pag...geindex=2#page

They used to think that inflammation = relapse, but MRI studies have indicated that we can be in a relapse with no inflammatory lesions apparent on our MRI, and/or not be in a clinical relapse but still have inflamed lesions showing.

The CRABs and Tysabri seem to be able to keep much of the inflammation and some % of relapses down . . . but in the long run, that approach hasn't proven to have a significant impact on disease progression/disability. It may make some difference though, I suppose.

Cherie