title: Imaging parameters of high grade gliomas in relation to the MGMT promoter methylation status: the CT, diffusion tensor imaging, and perfusion MR imaging.
abstract: BACKGROUND
  We hypothesized that methyl-guanine methyl transferase (MGMT) promoter methylation status, a predictor of the chemosensitivity for high grade gliomas (HGGs), may be associated with computed tomography (CT)/magnetic resonance (MR) imaging variables.
  
  
  METHODS
  Out of 38 consecutive patients with HGGs, 24 patients whose MGMT promoter methylation status was available [12 men and 12 women; median age, 49 years; age range, 22-79 years; WHO grade III (n = 7), WHO grade IV (n = 17)] were enrolled retrospectively. CT attenuation, apparent diffusion coefficient (ADC), fractional anisotropy (FA), and relative cerebral blood volume (rCBV) were measured for enhancing tumors. Qualitative imaging features were also analyzed. Mann-Whitney and Fisher's exact tests were used to evaluate relationships between MGMT promoter methylation status and imaging variables.
  
  
  RESULTS
  Maximum CT attenuation was significantly lower in the methylated MGMT promoter group than that in the unmethylated MGMT promoter group (30.3 ± 9.5 HU versus 39.2 ± 4.7 HU, respectively, p = 0.009). While ADC values tended to be higher in the methylated group than in the unmethylated group (p = 0.055), ADC ratio was significantly higher, and the FA and FA ratios were significantly lower in the methylated group than in the unmethylated group (p = 0.032, p = 0.006 and p = 0.007, respectively). In contrast, rCBV ratio did not differ between the two groups (p = 0.380).                         Regarding imaging features, only ill-defined margin was seen more frequently in the methylated group than in the unmethylated group (45.5% versus 7.7%, respectively, p = 0.048).
  
  
  CONCLUSIONS
  Preoperative imaging can predict MGMT promoter methylation status, which is of paramount importance for predicting treatment response to chemotherapy with an alkylating agent.
authors.affiliation: Department of Radiology, Konkuk University School of Medicine, 4-12, Hwayang-dong, Gwanjin-gu, Seoul, 143-792, South Korea. mdmoonwj@naver.com
authors.forename: Won-Jin
authors.initials: WJ
authors.lastname: Moon
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Choi
authors.forename: Hong Gee
authors.initials: HG
authors.lastname: Roh
authors.forename: So Dug
authors.initials: SD
authors.lastname: Lim
authors.forename: Young-Cho
authors.initials: YC
authors.lastname: Koh
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D003952:Diagnostic Imaging / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes