title: Midline medulloblastoma versus astrocytoma: the position of the superior medullary velum as a sign for diagnosis.
abstract: OBJECTIVE
  We wish to describe the position of the superior medullary velum (SMV) in midline posterior fossa tumours as a sign in helping to distinguish between midline medulloblastoma and midline astrocytoma.
  
  
  METHODS
  Sagittal T1-weighted MRI images of 21 consecutive patients with histologically documented posterior fossa midline astrocytomas (nine cases) and medulloblastomas (12 cases) were reviewed, with respect to the position of the velum medullare superius.
  
  
  RESULTS
  In all medulloblastomas the SMV was superiorly dislocated; in eight astrocytomas it was anteriorly and/or inferiorly disclocated; only in one astrocytoma the SMV presented upward dislocation.
  
  
  CONCLUSIONS
  In the differential diagnosis between medulloblastoma and astrocytoma the upward dislocation of the SMV is strongly suggestive of medulloblastoma.
authors.affiliation: Neuroradiology, Ospedale Sant'Andrea, University of Rome Sapienza, Rome, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Trasimeni
authors.forename: Jacopo
authors.initials: J
authors.lastname: Lenzi
authors.forename: Claudio
authors.initials: C
authors.lastname: Di Biasi
authors.forename: Giulio
authors.initials: G
authors.lastname: Anichini
authors.forename: Maurizio
authors.initials: M
authors.lastname: Salvati
authors.forename: Antonino
authors.initials: A
authors.lastname: Raco
mesh_terms: D001254:Astrocytoma / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D015192:Infratentorial Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008527:Medulloblastoma / Q000473:pathology*