PET imaging of brain astrocytoma with 1-11C-acetate.
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.
Liu
Ren-Shyan
RS
National PET/Cyclotron Center, Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. rsliu@vghtpe.gov.tw
Chang
Cheng-Pei
CP
Chu
Lee-Shing
LS
Chu
Yum-Kung
YK
Hsieh
Hung-Jen
HJ
Chang
Chi-Wei
CW
Yang
Bang-Hung
BH
Yen
Shan-Hui
SH
Huang
Min-Chao
MC
Liao
Su-Quin
SQ
Yeh
Shin-Hwa
SH
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
D000085:Acetates; D019275:Radiopharmaceuticals; C438206:carbon-11 acetate; D019788:Fluorodeoxyglucose F18; D002244:Carbon