title: Cytomegalovirus encephalitis: Undescribed diffusion-weighted imaging characteristics. Original aspects of cases extracted from a retrospective study, and from literature review.
abstract: BACKGROUND
  There is paucity of studies analyzing DWI in MRI sequences when imaging cytomegalovirus (CMV) meningoencephalitis. The main objective of this study is to demonstrate that DWI sequence is mandatory when imaging immunocompromised patients presenting with encephalitic symptoms, as this sequence can reveal very peculiar lesions in the setting of CMV encephalitis.
  
  
  METHODS
  Three CSF PCR CMV positive cases were identified in a 13-year retrospective study with MRI scans including T1, FLAIR, DWI with automated ADC calculation, and T1 with contrast injection, and were reviewed by a senior neuroradiologist.
  
  
  RESULTS
  Our three cases presented multiple high-signal intensity punctiform lesions in DWI, which uniformly were in restricted diffusion. Each patient had multiple lesions (mean 19.3, range 12-30): 96.5% were supratentorial and 3.5% were infratentorial. Among supratentorial lesions, 62.5% were subependymal, 28.6% were periventricular and 8.9% were subcortical. Some lesions remained in a long lasting restricted diffusion state. All cases had FLAIR curvilinear periventricular high signal intensities. No contrast uptake was found.
  
  
  CONCLUSIONS
  Punctiform DWI lesions had a clear ventricle wall tropism, consistent with classical autopsy findings. The classical histological knowledge-compatible explanation for long lasting diffusion restriction is non-lethal cytotoxic edema owing to CMV inclusions.
  
  
  CONCLUSIONS
  Subependymal and periventricular punctiform restricted diffusion lesions in the setting of meningoencephalitis in immunocompromised patients seem highly evocative of CMV encephalitis. The diffusion sequence probably reveals focal lesions constitutive of cellular viral inclusions.
authors.affiliation: Hospital Hotel-Dieu, Nantes, France. Electronic address: thibaut_renard@hotmail.fr.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Renard
authors.affiliation: Hospital Laennec, Saint-Herblain, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Daumas-Duport
authors.affiliation: Hospital Laennec, Saint-Herblain, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Auffray-Calvier
authors.affiliation: Hospital Laennec, Saint-Herblain, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Bourcier
authors.affiliation: Hospital Laennec, Saint-Herblain, France.
authors.forename: Hubert
authors.initials: H
authors.lastname: Desal
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology*; D003586:Cytomegalovirus Infections / Q000000981:diagnostic imaging* / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D008590:Meningoencephalitis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000821:virology; D008875:Middle Aged; D012189:Retrospective Studies
keywords: Cytomegalovirus; Encephalitis; MRI