title: Potential utility of conventional MRI signs in diagnosing pseudoprogression in glioblastoma.
abstract: OBJECTIVE
  To examine the potential utility of conventional MRI signs in differentiating pseudoprogression (PsP) from early progression (EP).
  
  
  METHODS
  This retrospective study reviewed initial postradiotherapy MRI scans of 321 patients with glioblastoma undergoing chemotherapy and radiotherapy. A total of 93 patients were found to have new or increased enhancing mass lesions, raising the possibility of PsP. Final diagnosis of PsP or EP was established upon review of surgical specimens from a second resection or by clinical and radiologic follow-up. A total of 11 MRI signs potentially helpful in the differentiation between PsP and EP were examined on the initial post-RT MRI and were correlated with the final diagnosis through χ(2) or Fisher exact test.
  
  
  RESULTS
  Sixty-three (67.7%) of the 93 patients had EP, of which 22 (34.9%) were diagnosed by pathology. Thirty patients (32.3%) had PsP; 6 (16.7% of the 30) were diagnosed by pathology. Subependymal enhancement was predictive for EP (p = 0.001) with 38.1% sensitivity, 93.3% specificity, and 41.8% negative predictive value. The other 10 signs had no predictive value (p = 0.06-1.0).
  
  
  CONCLUSIONS
  Conventional MRI signs have limited utility in diagnosing PsP in patients with recently treated glioblastomas and worsening enhancing lesions. We did not find a sign with a high negative predictive value for PsP that would have been the most useful for the clinical physician. When present, subependymal spread of the enhancing lesion is a useful MRI marker in identifying EP rather than PsP.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA. youngr@mskcc.org
authors.forename: R J
authors.initials: RJ
authors.lastname: Young
authors.forename: A
authors.initials: A
authors.lastname: Gupta
authors.forename: A D
authors.initials: AD
authors.lastname: Shah
authors.forename: J J
authors.initials: JJ
authors.lastname: Graber
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: W
authors.initials: W
authors.lastname: Shi
authors.forename: A I
authors.initials: AI
authors.lastname: Holodny
authors.forename: A M P
authors.initials: AM
authors.lastname: Omuro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology* / Q000528:radiation effects; D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D002648:Child; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D005909:Glioblastoma / Q000473:pathology* / Q000532:radiotherapy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D055815:Young Adult