title: Virchow-Robin spaces on magnetic resonance images: normative data, their dilatation, and a review of the literature.
abstract: BACKGROUND
  Virchow-Robin spaces (VRS) are perivascular spaces in the brain and can be visualized on magnetic resonance images (MRI). We attempt to provide a better understanding of the significance of VRS for pathological and physiological processes by reviewing the literature, presenting normative data for the first time, and proposing a definition for the dilatation of the VRS on MRI that is based on shape rather than size.
  
  
  METHODS
  We evaluated the VRS in 125 healthy subjects (age range 1-30 years) using high-resolution 3D images, and in 36 patients (age range 2-16 years) with normal MRI, using routine clinical sequences.
  
  
  RESULTS
  VRS were visible in all high-resolution images of the 125 healthy subjects. Two of them revealed dilated VRS, giving a prevalence of 1.6%. VRS could be visualized in 29 (80%) of the 36 paediatric clinical scans; none was dilated. It was demonstrated that the visibility of VRS on MRI is sequence-dependent.
  
  
  CONCLUSIONS
  From the results of this study and the literature on the nature and pathology of VRS, we conclude that VRS on MR images of healthy individuals are normal findings, even if they are dilated. A judgement on whether dilated VRS in an individual patient is a normal variant or part of a disease process can be made by taking into account the appearance of the adjacent tissue on MRI and the clinical context.
authors.affiliation: Department of Pediatrics and Child Neurology, Georg-August-University, Goettingen, Germany.
authors.forename: Samuel
authors.initials: S
authors.lastname: Groeschel
authors.forename: Wui Khean
authors.initials: WK
authors.lastname: Chong
authors.forename: Robert
authors.initials: R
authors.lastname: Surtees
authors.forename: Folker
authors.initials: F
authors.lastname: Hanefeld
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000473:pathology* / Q000503:physiopathology; D001927:Brain Diseases / Q000473:pathology* / Q000503:physiopathology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D004108:Dilatation, Pathologic / Q000473:pathology; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008833:Microcirculation / Q000502:physiology; D012016:Reference Values