title: The surgical bed after BCNU polymer wafer placement for recurrent glioma: serial assessment on CT and MR imaging.
abstract: OBJECTIVE
  The objective of our study was to describe the CT and MR imaging appearances of the surgical bed in the brains of patients receiving biodegradable polymers impregnated with N, N'1, 3-Bis-(2-chloroethyl)-N-nitrosourea (BCNU) for recurrent glioma and to determine whether patients receiving placebos could be differentiated from those receiving BCNU based on the pattern and growth kinetics of tumor recurrence.
  
  
  METHODS
  The CT and MR images of 20 patients who underwent surgery for resection of recurrent high-grade gliomas and placement of intratumoral wafers (11 received BCNU polymer wafers, nine received control wafers) were analyzed for wafer appearance, volume of gas in the tumor bed, and volume of enhancement on serial scans.
  
  
  RESULTS
  Wafers appeared as linear hyperdense structures on CT and as linear low-signal-intensity structures on MR imaging and caused no significant enhancement. In the BCNU polymer group, gas volume was 4.0 +/- 3.4 cm(3) (mean +/- SD), whereas gas volume was 1.6 +/- 3.0 cm(3) for the placebo group (Mann-Whitney test, p = 0.03). A trend toward linear rather than exponential recurrent tumor growth was identified for the BCNU polymer group but not for the placebo group.
  
  
  CONCLUSIONS
  BCNU polymer wafers have a specific appearance on CT and MR imaging with which radiologists should be familiar: gas in the surgical bed is an expected transient finding, and tumor regrowth in patients receiving BCNU polymer wafers appeared to occur at a slower rate than in those receiving the placebo.
authors.affiliation: Department of Radiology, Division of Neuroradiology, The Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287-2182, USA.
authors.forename: Dima A
authors.initials: DA
authors.lastname: Hammoud
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Belden
authors.forename: Amy C
authors.initials: AC
authors.lastname: Ho
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Dal Pan
authors.forename: Edward H
authors.initials: EH
authors.lastname: Herskovits
authors.forename: Dana C
authors.initials: DC
authors.lastname: Hilt
authors.forename: Henry
authors.initials: H
authors.lastname: Brem
authors.forename: Martin G
authors.initials: MG
authors.lastname: Pomper
mesh_terms: D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D002330:Carmustine / Q000008:administration & dosage*; D004333:Drug Administration Routes; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D018906:Antineoplastic Agents, Alkylating; D002330:Carmustine