title: PET imaging of brain astrocytoma with 1-11C-acetate.
abstract: OBJECTIVE
  The purpose of this study was to assess the use of 1-(11)C-acetate (ACE) as a metabolic tracer for the detection and characterisation of astrocytomas.
  
  
  METHODS
  Positron emission tomography (PET) studies with ACE and 2-(18)F-fluoro-2-deoxy-D-glucose (FDG) were performed sequentially in 26 patients with primary astrocytomas. Images were analysed by visual interpretation and determination of the tumour to cortex ratio (T/C ratio) and standardised uptake value (SUV). The tumour uptake was visually scored into three grades as compared with the contralateral cortex: clearly lower (-), almost equal (+) and clearly higher (++).
  
  
  RESULTS
  There were 85% of astrocytomas with ++ ACE uptake, 15% with + ACE uptake and none with - ACE uptake. Only 19% of astrocytomas had ++ FDG uptake. Thirty-seven percent of high-grade astrocytomas had + FDG uptake and 37% had - FDG uptake. The sensitivity and specificity of the FDG T/C ratio in discriminating high-grade from low-grade astrocytomas were 79% and 100%, respectively, at the cutoff value of 0.75. Using 2.33 as the cutoff value of the ACE T/C ratio, the sensitivity and specificity were 42% and 86%, respectively. FDG was better than ACE in discriminating high-grade from low-grade astrocytomas. T/C ratios and SUVs of FDG uptake of tumours correlated with the histological grades, but those of ACE uptake did not.
  
  
  CONCLUSIONS
  ACE appears to be a promising tracer for use in the detection of primary astrocytomas, but is of limited value in the differentiation of high- and low-grade astrocytomas. ACE is complementary to FDG for the diagnosis and characterisation of astrocytoma.
authors.affiliation: National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. rsliu@vghtpe.gov.tw
authors.forename: Ren-Shyan
authors.initials: RS
authors.lastname: Liu
authors.forename: Cheng-Pei
authors.initials: CP
authors.lastname: Chang
authors.forename: Lee-Shing
authors.initials: LS
authors.lastname: Chu
authors.forename: Yum-Kung
authors.initials: YK
authors.lastname: Chu
authors.forename: Hung-Jen
authors.initials: HJ
authors.lastname: Hsieh
authors.forename: Chi-Wei
authors.initials: CW
authors.lastname: Chang
authors.forename: Bang-Hung
authors.initials: BH
authors.lastname: Yang
authors.forename: Shan-Hui
authors.initials: SH
authors.lastname: Yen
authors.forename: Min-Chao
authors.initials: MC
authors.lastname: Huang
authors.forename: Su-Quin
authors.initials: SQ
authors.lastname: Liao
authors.forename: Shin-Hwa
authors.initials: SH
authors.lastname: Yeh
mesh_terms: D000085:Acetates; D000328:Adult; D001254:Astrocytoma / Q000000981:diagnostic imaging*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D002244:Carbon; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000085:Acetates; D019275:Radiopharmaceuticals; C438206:carbon-11 acetate; D019788:Fluorodeoxyglucose F18; D002244:Carbon