Natalizumab (Tysabri)-Associated Progressive Multifocal Leukoencephalopathy: Insights From Perfusion Magnetic Resonance ImagingElster, Martha J. BAJournal of Computer Assisted Tomography: September/October 2013 - Volume 37 - Issue 5 - p 694–697 doi: 10.1097/RCT.0b013e318298aa0d Neuroradiology Abstract Author Information A case of natalizumab-associated progressive multifocal leukoencephalopathy in a 38-year-old woman is presented showing characteristics on magnetic resonance imaging (MRI) with high signal on T2-weighted images and patchy contrast enhancement. After 5 days of plasma exchange therapy, contrast enhancement decreased, but the abnormality on T2-weighted images increased. Perfusion MRI at this time demonstrated significantly increased blood flow to the lesion. Thirteen days after initiation of treatment, perfusion MR returned to normal in advance of significant anatomical changes on conventional MRIs. This case suggests that MR perfusion imaging may be helpful in monitoring the treatment of patients with natalizumab-associated progressive multifocal leukoencephalopathy. From the Department of Radiology, Wake Forest School of Medicine, Wake Forest University, Winston-Salem, NC. Received for publication April 21, 2013; accepted April 23, 2013. The author has no conflict of interest to declare. Reprints: Martha J. Elster, BA, Department of Radiology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157 (e-mail: firstname.lastname@example.org). Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.