title: Magnetic resonance imaging appearance and changes on intracavitary Gliadel wafer placement: A pilot study.
abstract: OBJECTIVE
  To investigate changes on magnetic resonance imaging (MRI) which occur with intracavitary Gliadel wafer placement in patients with glioblastoma multiforme (GBM).
  
  
  METHODS
  This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by the institutional review board, with a waiver of informed consent. A total of eight patients aged 29-67 years with GBM underwent Gliadel wafer placement. T2-weighted/FLAIR images and post-contrast T1-weighted images both before and after wafer placement were retrospectively reviewed in consensus to determine changes in the following parameters: appearance of the pericavitary tissue, pattern of tumor recurrence or progression and appearance of the Gliadel wafer itself.
  
  
  RESULTS
  Five out of the eight patients had a progressive increase in enhancement and pericavitary T2/ FLAIR hyperintensity within the first 2 mo and a subsequent decrease in these MRI findings. None of these patients had tumor recurrence within the first 6 mo. Three out of the eight patients demonstrated a progressive increase in enhancement and pericavitary T2 hyperintensity, which continued after the first 6 mo, and were subsequently diagnosed with true tumor progression. There was no increase in distant/nonlocal tumor recurrence. The Gliadel wafer appearance changed over time.
  
  
  CONCLUSIONS
  Pseudoprogression is common after intracavitary Gliadel wafer placement and thus care should be taken before diagnosing tumor progression or recurrence within the first 2 mo.
authors: Rivka R Colen, Department of Radiology, Brigham and Women's Hospital, Boston, MA 02115, United States.
authors: Rivka R
authors: RR
authors: Colen
authors: Pascal O
authors: PO
authors: Zinn
authors: Saman
authors: S
authors: Hazany
authors: Daniel
authors: D
authors: Do-Dai
authors: Julian K
authors: JK
authors: Wu
authors: Kevin
authors: K
authors: Yao
authors: Jay J
authors: JJ
authors: Zhu