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Abstract #3220

MRI Evidence That Gadolinium-Enhancing Lesions Seen Twelve Weeks After Commencing Rituximab Treatment Are Associated with Lower Blood-Brain-Barrier Disruption Than Those Seen Prior to Treatment in Patients with Relapsing-Remitting Multiple Sclerosis

Zografos Caramanos1,2, Ilana Leppert1, Sridar Narayanan1,2, G Bruce Pike1, Douglas Lorne Arnold1,2

1McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada; 2NeuroRx Research, Montreal, Quebec, Canada

Building on previous findings that treatment with rituximab results in decreased gadolinium-enhancing (<B>Gd+</B>) lesion counts and volumes in patients with relapsing-remitting multiple sclerosis (<B>MS</B>), we found evidence that Gd+ lesions seen twelve weeks post-rituximab exhibit significantly lower blood-brain barrier (<B>BBB</B>) disruption than those seen pre-treatment. This suggests that a continuous classification of BBB disruption in patients with MS may reveal treatment-related changes that are not detected by the conventional, binary classification of lesions as being Gd+ or not. Furthermore, our results suggest that the practical measure of BBB disruption that we used can provide additional information that is independent of that provided by Gd+ lesion volume.