Standardized brain MRIs with and without gadolinium contrast will be obtained at baseline, and month 6, 12, 18 and 24 months (for those patients reaching this point prior to the last enrolled patient reaching the 12 months follow-up visit) at UCD Anschutz Medical Campus. The treating clinician will have access to the MRI and can discuss the results openly with subjects. Standardized MRIs will be obtained and interpreted locally by a physician who will be blinded to the subject treatment to record the endpoints described above.