title: Diffusion-weighted MR imaging for the differentiation of true progression from pseudoprogression following concomitant radiotherapy with temozolomide in patients with newly diagnosed high-grade gliomas.
abstract: OBJECTIVE
  The assessment of the therapeutic response of high-grade gliomas treated with concomitant chemoradiotherapy (CCRT) using temozolomide is difficult because of the frequent occurrence of early imaging changes that are indistinguishable from tumor progression, termed pseudoprogression. The purpose of this study was to determine whether diffusion-weighted imaging could be used to differentiate true progression and pseudoprogression.
  
  
  METHODS
  Magnetic resonance images and diffusion-weighted images obtained within 2 months of CCRT completion in patients with high-grade gliomas were retrospectively reviewed. A total of 22 patients with increases in measurable enhancing regions were identified and classified into true progression and pseudoprogression groups on the basis of contrast-enhanced magnetic resonance images obtained 12 weeks after CCRT. Qualitative and quantitative analysis of diffusion-weighted images and apparent diffusion coefficient maps, respectively, was performed to discriminate true progression and pseudoprogression. Statistical analyses were performed using Fisher's exact test, unpaired t tests, and receiver-operating characteristic analysis.
  
  
  RESULTS
  The true progression group showed a higher incidence of homogeneous or multifocal high signal intensity on diffusion-weighted images (seven of 10 patients [70%]), whereas rim high or no high signal intensity (10 of 12 [83%]) was observed in the pseudoprogression group (P = .027). True progression was defined by newly appearing or enlarged enhancing lesions with mean apparent diffusion coefficient values of 1200 × 10(-6) mm(2)/s inside the radiation field after CCRT; the sensitivity, specificity, and accuracy were 80% (eight of 10), 83.3% (10 of 12), and 81.2% (18 of 22), respectively.
  
  
  CONCLUSIONS
  The assessment of diffusion-weighted images for patients with increases of measurable enhancing regions 2 months after CCRT completion is useful for differentiating true progression from pseudoprogression.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Yongon-dong, Chongno-gu, Korea.
authors.forename: Woong Jae
authors.initials: WJ
authors.lastname: Lee
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.forename: Chul-Kee
authors.initials: CK
authors.lastname: Park
authors.forename: Kyung Sik
authors.initials: KS
authors.lastname: Yi
authors.forename: Tae Min
authors.initials: TM
authors.lastname: Kim
authors.forename: Se-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
authors.forename: Sung-Hye
authors.initials: SH
authors.lastname: Park
authors.forename: Il Han
authors.initials: IH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D016477:Artifacts; D001932:Brain Neoplasms / Q000473:pathology* / Q000628:therapy*; D059248:Chemoradiotherapy / Q000379:methods*; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000627:therapeutic use; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005910:Glioma / Q000473:pathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000077204:Temozolomide; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D018906:Antineoplastic Agents, Alkylating; D003606:Dacarbazine; D000077204:Temozolomide