[11C] acetoacetate utilization by breast and prostate tumors:: A PET and biodistribution study in mice

Purpose: A significant positive correlation has been observed between ketone body availability and their uptake by tumor cells. Our objective was to evaluate [(11)C] acetoacetate as a potential tracer of ketone body utilization by breast and prostate tumors and to compare it with [(11)C] acetate. Methods: Biodistribution studies were performed with [(11)C] acetoacetate and [(11)C] acetate in mice bearing breast or prostate tumors. The percentage of the injected dose accumulated per gram of tissue was determined. These results were complemented by dynamic positron emission tomography ( PET) imaging of the radiotracer uptake and dosimetry calculations. Results: [(11)C] Acetoacetate uptake was optimal between 5 and 30 min, with maximal uptake of 2.72, 2.42, 2.54, and 2.19% injected dose (%ID)/g for MC7-L1, MC4-L2, PC3, and LN-CaP tumors respectively. Tumor retention for [(11)C] acetoacetate tended to be higher than [ 11C] acetate, but this did not reach statistical significance. [(11)C] Acetate uptake was reached within 15 min with optimal uptake of 1.25, 2.30, and 0.96%ID/g for MC7-L1, MC4-L2, and PC-3 tumors, respectively. Conclusions: We observed a moderate uptake of [(11)C] acetoacetate in breast and prostate tumors with low background activity due to rapid elimination of this tracer. Further studies are warranted to determine if this tracer can detect slow-growing breast and prostate cancers in the clinical setting.