title: MRI characteristics of early PML-IRIS after natalizumab treatment in patients with MS.
abstract: The early detection of MRI findings suggestive of immune reconstitution inflammatory syndrome (IRIS) in natalizumab-associated progressive multifocal leukoencephalopathy (PML) is of crucial clinical relevance in terms of treatment decision-making and clinical outcome. The aim of this study was to investigate the earliest imaging characteristics of PML-IRIS manifestation in natalizumab-treated patients with multiple sclerosis and describe an imaging pattern that might aid in the early and specific diagnosis.
  
  
  
  This was a retrospective study assessing brain MRI of 26 patients with natalizumab-associated PML presenting with lesions suggestive of PML-IRIS during follow-up. MRI findings were evaluated considering the imaging findings such as mass effect, swelling, contrast enhancement, new perivascular T2 lesions and signs suggestive of meningeal inflammation.
  
  
  
  Contrast enhancement was the most common imaging sign suggestive of PML-IRIS, seen in 92.3% of the patients (with patchy and/or punctuate pattern in 70.8% and 45.8% respectively), followed by new T2 lesions with a perivascular distribution pattern (34.6%). In those patients with contrast enhancement, the enhancement was present in the lesion periphery in 95.8% of the patients. Contrast-enhancing lesions with a perivascular distribution pattern outside of the PML lesion were observed in 33.3% of the patients. The most common overall pattern was contrast enhancement in the border of the PML lesion with either a patchy or punctuate appearance in 88.5% of all patients.
  
  
  
  Contrast enhancement is the most common earliest sign of natalizumab-associated PML-IRIS with a frequent imaging pattern of contrast-enhancing lesions with either a patchy or punctuate appearance in the border of the PML lesion.
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Mike P
authors.initials: MP
authors.lastname: Wattjes
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Martijn T
authors.initials: MT
authors.lastname: Wijburg
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Anke
authors.initials: A
authors.lastname: Vennegoor
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Birgit I
authors.initials: BI
authors.lastname: Witte
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marlieke
authors.initials: M
authors.lastname: de Vos
authors.affiliation: Multiple Sclerosis Clinical Development Group, Biogen, Cambridge, Massachusetts, USA.
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Richert
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Bernard M J
authors.initials: BM
authors.lastname: Uitdehaag
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Frederik
authors.initials: F
authors.lastname: Barkhof
authors.affiliation: MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Joep
authors.initials: J
authors.lastname: Killestein
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D054019:Immune Reconstitution Inflammatory Syndrome / Q000139:chemically induced* / Q000150:complications / Q000000981:diagnostic imaging*; D007968:Leukoencephalopathy, Progressive Multifocal / Q000139:chemically induced* / Q000150:complications / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D000069442:Natalizumab / Q000009:adverse effects* / Q000627:therapeutic use*; D059906:Neuroimaging; D012189:Retrospective Studies
chemical_list: D000069442:Natalizumab