title: MR imaging characteristics of protoplasmic astrocytomas.
abstract: BACKGROUND
  Protoplasmic astrocytomas are a poorly recognized and uncommon subtype of astrocytoma. While usually categorized with other low-grade gliomas, there is literature to suggest that protoplasmic astrocytomas have differences in biology compared to other gliomas in this group. This paper presents the MR imaging characteristics of a series of eight protoplasmic astrocytomas.
  
  
  METHODS
  We retrospectively reviewed MR images and histopathology of eight consecutive cases of histologically proven protoplasmic astrocytomas.
  
  
  RESULTS
  Patients ranged from 17 to 51 years of age with a 5:3 male to female ratio. The tumors were located in the frontal or temporal lobes and tended to be large, well defined, and had a very high signal on T2 (close to cerebrospinal fluid). Generally, a large proportion of the tumor showed substantial signal suppression on T2 fluid-attenuated inversion recovery (FLAIR). Six of the eight lesions also demonstrated a partial or complete rim of reduced apparent diffusion coefficient (ADC) around the T2 FLAIR suppressing portion.
  
  
  CONCLUSIONS
  The possibility that a primary cerebral neoplasm represents a protoplasmic astrocytoma should be considered in a patient with a large frontal or temporal tumor that has a very high signal on T2 with a large proportion of the tumor showing substantial T2 FLAIR suppression. A further clue is a partial or complete rim of reduced ADC.
authors.affiliation: Department of Radiology, Royal Melbourne Hospital, Parkville, Victoria, Australia. ktay@nsccahs.health.nsw.gov.au
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Tay
authors.forename: Alpha
authors.initials: A
authors.lastname: Tsui
authors.forename: Pramit M
authors.initials: PM
authors.lastname: Phal
authors.forename: Katharine J
authors.initials: KJ
authors.lastname: Drummond
authors.forename: Brian M
authors.initials: BM
authors.lastname: Tress
mesh_terms: D000293:Adolescent; D000328:Adult; D001254:Astrocytoma / Q000175:diagnosis* / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013702:Temporal Lobe / Q000473:pathology; D055815:Young Adult