1-11C-acetate versus 18F-FDG PET in detection of meningioma and monitoring the effect of gamma-knife radiosurgery.

UNLABELLED: This study aimed to define the potential of 1-(11)C-acetate PET, compared with (18)F-FDG, in detecting meningiomas and monitoring the effect of gamma-knife radiosurgery. METHODS: Twenty-two patients with the neuroradiologic diagnosis of meningioma were examined by 1-(11)C-acetate and (18)F-FDG PET on the same day. There were 12 cases of histopathologically proven meningioma (8 grade I, 2 grade II, and 2 grade III), 1 of tuberculous granuloma, and 1 of degenerative tissue. 1-(11)C-acetate PET scans of fasting patients were obtained 10 min after intravenous administration of 740 MBq of 1-(11)C-acetate. (18)F-FDG PET was performed at 2 h after 1-(11)C-acetate scanning. The PET images were evaluated by a qualitative method and semiquantitative analysis using standardized uptake value and tumor-to-cortex ratio. RESULTS: The (18)F-FDG PET study revealed a hypometabolic focus in 17 meningiomas (8 grade I, 1 grade II, and 8 unknown grade) and hypermetabolism in 1 grade II and 2 grade III meningiomas. High uptake of 1-(11)C-acetate was observed in all 20 meningiomas, in contrast to the low uptake in surrounding normal brain tissue, allowing a clearer demarcation of the tumor boundary than that provided by (18)F-FDG. Dissociation of regional accumulation of 1-(11)C-acetate and (18)F-FDG within the tumor was also noted on the coregistered images. The standardized uptake value for 1-(11)C-acetate was not different from that for (18)F-FDG (mean +/- SD, 3.16 +/- 1.75 vs. 3.22 +/- 1.50, P = 0.601), but the tumor-to-cortex ratio for 1-(11)C-acetate was higher than that for (18)F-FDG (3.46 +/- 1.38 vs. 0.93 +/- 1.08, P < 0.005). (18)F-FDG was able to differentiate grade I from grade II-III meningiomas, whereas 1-(11)C-acetate was unable to do so. Tuberculous granuloma had a high 1-(11)C-acetate and (18)F-FDG uptake similar to that of grade II/III meningioma. Five patients received 1-(11)C-acetate and (18)F-FDG PET before and after gamma-knife surgery. 1-(11)C-acetate performed better than did (18)F-FDG in monitoring the response of tumor metabolism to radiosurgery. CONCLUSION: 1-(11)C-acetate was found to be useful for detecting meningiomas and evaluating the extent of meningiomas and potentially useful for monitoring tumor response to radiosurgery. However, 1-(11)C-acetate was not useful for evaluating the tumor grade. (18)F-FDG was found to be less useful than 1-(11)C-acetate for evaluating the extent of meningiomas and the response to radiosurgical treatment but may be useful for differentiating benign from malignant meningiomas. (18)F-FDG and 1-(11)C-acetate are complementary for assessing diverse cell metabolism of meningioma.

Specific activation of sodium iodide symporter gene in hepatoma using alpha-fetoprotein promoter combined with hepatitis B virus enhancer (EIIAPA).

BACKGROUND: This study aimed to develop a novel tumor-specific promoter gene linking sodium iodide symporter (NIS) gene to specifically target hepatocellular carcinoma in a mouse tumor model. MATERIALS AND METHODS: A tumor-specific chimeric promoter for alpha-fetoprotein gene (AFP) was combined with hepatitis B virus (HBV) enhancer II to investigate radioiodine uptake in vitro and in vivo in hepatoma (HepG2) and nonhepatoma (ARO) cell lines after transfer of hNIS gene. A lentiviral vector carrying the hNIS gene was employed in vitro and in vivo. Radionuclide imaging was acquired for 30 min at 60 min after administration of 1241 to monitor hNIS gene expression in vivo using microPET. RESULTS: The highest radioiodide uptake of ARO and HepG2 clones which stably expressed hNIS gene were 87- and 208-fold higher than that of parental cells, respectively. After infection of lentivirus, hNIS gene controlled by cytomegavirus (CMV) promoter was expressed in both ARO and HepG2 cells, and hNIS gene induction by EIIAPA promoter was higher than by CMV promoter in HepG2 cells but not in ARO cells. A similar result was observed in vivo, hNIS controlled by CMV promoter was highly expressed in both HepG2 and ARO tumors. The HepG2 tumor multi-infected with LV-EIIAPA-hNIS virus specifically, but the ARO tumor did not activate the EIIAPA promoter and further express the hNIS protein. CONCLUSION: Transduction of the hNIS gene controlled by the novel EIIAPA chimeric promoter successfully induces iodide transport in hepatoma.

PET imaging of brain astrocytoma with 1-11C-acetate.

PURPOSE: 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. CONCLUSION: 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.