title: ¹⁸F-fluorodeoxyglucose and ¹¹C-methionine positron emission tomography in relation to methyl-guanine methyltransferase promoter methylation in high-grade gliomas.
abstract: BACKGROUND
  Methylation status of the methyl-guanine methyltransferase (MGMT) promoter is associated with a favorable response to a DNA alkylating agent in high-grade gliomas. We analyzed PET scans of patients with high-grade gliomas to determine whether the MGMT methylation status affects the tumor metabolic characteristics.
  
  
  METHODS
  Twenty-three patients with high-grade glioma, who were initially examined with 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) PET, were retrospectively enrolled. MET and FDG PET images were coregistered to each other and quantitative uptake of MET or FDG was assessed using tumor-to-normal uptake ratio of the cortex (TNR). TNRs for MET and FDG PET were compared between the two groups classified by MGMT promoter methylation status.
  
  
  RESULTS
  Maximum TNR(FDG) of the MGMT methylated group was significantly higher than that of the MGMT unmethylated group (1.80±0.90 vs. 1.29±0.19; P=0.02). The MGMT methylated group also showed a trend for increased mean TNRFDG compared with the unmethylated group (0.85±0.21 vs. 0.72±0.11; P=0.10). There was no significant difference in TNR(MET) between the groups. In subgroup analyses with WHO grade 3 and 4, a trend for higher maximum TNR(FDG) was found in the MGMT methylated group compared with the unmethylated group.
  
  
  CONCLUSIONS
  The MGMT methylated group showed higher glucose metabolism compared with the unmethylated group, whereas MET uptake did not show a significant difference. This suggests that MGMT methylation in high-grade gliomas could affect the tumor glucose metabolism. Thus, MGMT methylation status can cause a discrepancy in the prognostic prediction of high-grade gliomas by FDG PET, especially in patients scheduled for DNA alkylating chemotherapeutics.
authors.affiliation: aDepartment of Nuclear Medicine, Seoul National University Hospital bDepartment of Molecular Medicine and Biopharmaceutical Science, Graduate School of Concergence Science and Technology cCancer Research Institute, Seoul National University dDepartment of Neurosurgery eDepartment of Pathology, Seoul National University College of Medicine, Seoul, Korea fDepartment of Radiological Sciences, University of California at Irvine, California, USA.
authors.forename: Hongyoon
authors.initials: H
authors.lastname: Choi
authors.forename: Ji-In
authors.initials: JI
authors.lastname: Bang
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Yong Hwy
authors.initials: YH
authors.lastname: Kim
authors.forename: Chul-Kee
authors.initials: CK
authors.lastname: Park
authors.forename: Sung-Hye
authors.initials: SH
authors.lastname: Park
authors.forename: Keon Wook
authors.initials: KW
authors.lastname: Kang
authors.forename: June-Key
authors.initials: JK
authors.lastname: Chung
authors.forename: Euishin E
authors.initials: EE
authors.lastname: Kim
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D019175:DNA Methylation; D005260:Female; D019788:Fluorodeoxyglucose F18; D005910:Glioma / Q000000981:diagnostic imaging* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D006801:Humans; D008297:Male; D008715:Methionine; D008875:Middle Aged; D060787:Neoplasm Grading; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics*; D049268:Positron-Emission Tomography; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18; C086242:carbon-11 methionine; D008715:Methionine; D019853:O(6)-Methylguanine-DNA Methyltransferase