title: Does adding FDG-PET to MRI improve the differentiation between primary cerebral lymphoma and glioblastoma? Observer performance study.
abstract: OBJECTIVE
  It is sometimes difficult to distinguish between primary central nervous system lymphomas (PCNSL) and glioblastoma multiforme (GBM). The aim of this study was to investigate whether the addition of (18)F-2-fluoro-2-deoxy-D: -glucose positron emission tomography ([(18)F]FDG-PET) and apparent diffusion coefficients (ADC) to conventional MRI improves diagnostic accuracy for distinguishing between PCNSL and GBM with similar MRI findings.
  
  
  METHODS
  We used conventional- and diffusion-weighted MRI and FDG-PET scans of 21 patients with histologically confirmed brain tumors exhibiting similar MRI findings (PCNSL, n = 14, GBM, n = 7) in our observer performance study that consisted of 3 interpretation sessions. ADC and maximum standard uptake values (SUV(max)) of the tumors were calculated. Three radiologists first interpreted conventional MRI (1st session), then they read images to which the ADC value had been added (2nd session), and finally they interpreted images supplemented with SUV(max) (3rd session). Observer performance was evaluated using κ statistic and receiver operating characteristics analyses.
  
  
  RESULTS
  The addition of ADC values to conventional MRI failed to improve the differentiation between PCNSL and GBM. The addition of SUV(max) at the third session improved the diagnostic accuracy of all 3 readers and resulted in higher interobserver agreement; mean accuracy was 95% (range 93-100%). In one observer the accuracy of tumor differentiation was significantly improved at the third compared to the second session (p = 0.017).
  
  
  CONCLUSIONS
  In a selected group of PCNSL and GBM with similar MRI findings, the addition of quantitative FDG-PET to MRI may improve their differentiation. ADC measurement did not allow further discrimination.
authors.affiliation: Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Makino
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Hideo
authors.initials: H
authors.lastname: Nakamura
authors.forename: Ryuji
authors.initials: R
authors.lastname: Murakami
authors.forename: Mika
authors.initials: M
authors.lastname: Kitajima
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shigematsu
authors.forename: Rumi
authors.initials: R
authors.lastname: Nakashima
authors.forename: Shinya
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uetani
authors.forename: Koya
authors.initials: K
authors.lastname: Iwashita
authors.forename: Masuma
authors.initials: M
authors.lastname: Akter
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Kuratsu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D004058:Diffusion; D005260:Female; D019788:Fluorodeoxyglucose F18; D005909:Glioblastoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D049268:Positron-Emission Tomography; D012372:ROC Curve
chemical_list: D019788:Fluorodeoxyglucose F18