title: Diagnosis of natalizumab-associated progressive multifocal leukoencephalopathy using MRI.
abstract: OBJECTIVE
  This review describe the role and advancements of MRI in the diagnosis and monitoring of progressive multifocal leukoencephalopathy (PML) in multiple sclerosis patients treated with natalizumab.
  
  
  RESULTS
  MRI is the most sensitive paraclinical tool in the detection of PML lesions in natalizumab-treated multiple sclerosis patients, showing lesions in very early disease stages up to months before clinical symptoms occur. The sensitivity of PML lesion detection is dependent on the MRI pulse-sequences used. Fluid-attenuated inversion recovery shows the highest sensitivity and diffusion-weighted MRI is well suited to depict active and acute demyelination in PML lesions. Compared with the PML in HIV-infected patients, the MRI appearance of natalizumab-associated PML is rather heterogeneous and fluctuating, including signs of inflammation and showing new imaging patterns such as cortical grey matter involvement. The importance of reliable PML detection is particularly obvious in patients at an asymptomatic stage. The clinical relevance of natalizumab-associated PML detected at an asymptomatic stage is best illustrated by the fact that such patients have a substantially better outcome compared with symptomatic PML patients.
  
  
  CONCLUSIONS
  MRI is the most powerful method in the detection of natalizumab-associated PML by showing imaging patterns helpful in the differentiation between PML and multiple sclerosis lesions. The early - preferably asymptomatic - detection of PML is related to a more favorable outcome in terms of survival and functional outcome parameters.
authors.affiliation: Department of Radiology & Nuclear Medicine, MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Mike P
authors.initials: MP
authors.lastname: Wattjes
authors.forename: Frederik
authors.initials: F
authors.lastname: Barkhof
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000009:adverse effects* / Q000276:immunology; D001921:Brain / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects* / Q000276:immunology; D007968:Leukoencephalopathy, Progressive Multifocal / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology; D008279:Magnetic Resonance Imaging; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000276:immunology; D000069442:Natalizumab
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D007166:Immunosuppressive Agents; D000069442:Natalizumab