title: Angiographic abnormalities in progressive multifocal leukoencephalopathy: an explanation based on neuropathologic findings.
abstract: OBJECTIVE
  Progressive multifocal leukoencephalopathy (PML) is typically occult at angiography and fails to enhance on MR images. After observing angiographic abnormalities characterized by arteriovenous shunting and pathologic parenchymal blush in patients with AIDS-related PML, often in the absence of contrast enhancement on MR images, we hypothesized that there might be distinct changes in the cerebral microvasculature that account for the reduction in vascular transit time (arteriovenous shunting) in the absence of blood-brain barrier dysfunction.
  
  
  METHODS
  The imaging studies and neuropathologic specimens of six patients with biopsy-proved PML were reviewed retrospectively. In all patients contrast-enhanced MR imaging and CT, followed by cerebral angiography, were performed before stereotactically directed biopsy. The angiograms were evaluated for the presence of vascular displacement, pathologic parenchymal blush, arteriovenous shunting, and neovascularity. The CT and MR studies were reviewed for the presence of enhancement of the PML lesions. Biopsy specimens were examined for the presence of necrosis, perivascular inflammation, and neovascularity.
  
  
  RESULTS
  All patients had oligodendrocytic intranuclear inclusions diagnostic of PML, together with perivascular inflammation and neovascularity to a varying extent; no other neuropathologic processes were identified. Angiographic abnormalities, characterized by a pathologic parenchymal blush and arteriovenous shunting, were identified in four of the six patients. In only one of these cases, however, was abnormal enhancement identified on cross-sectional imaging studies (MR and CT), and this patient had florid perivascular inflammatory infiltrates histologically.
  
  
  CONCLUSIONS
  The pathologic parenchymal blush and arteriovenous shunting seen angiographically in some patients with PML reflect small-vessel proliferation and perivascular inflammatory changes incited by the presence of the JC virus in infected oligodendrocytes.
authors.affiliation: Department of Radiology, New York University Medical Center, NY 10016, USA.
authors.forename: P K
authors.initials: PK
authors.lastname: Nelson
authors.forename: L T
authors.initials: LT
authors.lastname: Masters
authors.forename: D
authors.initials: D
authors.lastname: Zagzag
authors.forename: P J
authors.initials: PJ
authors.lastname: Kelly
mesh_terms: D015526:AIDS Dementia Complex / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D000328:Adult; D019412:Anatomy, Cross-Sectional; D001163:Arteriovenous Anastomosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D001706:Biopsy; D001812:Blood-Brain Barrier; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology; D003287:Contrast Media; D005260:Female; D006801:Humans; D002479:Inclusion Bodies / Q000473:pathology; D007968:Leukoencephalopathy, Progressive Multifocal / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D009336:Necrosis; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging / Q000473:pathology; D009836:Oligodendroglia / Q000473:pathology; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media