PET with 11C-acetate (11C-ACE) has a high sensitivity for detection of prostate cancer and several other cancers that are poorly detected with 18F-FDG. However, the short half-life (20.4 min) of 11C limits the general availability of 11C-ACE. 18F-Fluoroacetate (18F-FAC) is an analog of acetate with a longer radioactive half-life (18F = 110 min). This study was undertaken to assess the potential usefulness of 18F-FAC as a prostate tumor imaging agent. Methods: We developed an efficient radiosynthesis for 18F-FAC, which has already been adapted to a commercial synthesizer. Biodistribution studies of 18F-FAC were compared with 11C-ACE in normal Sprague-Dawley male rats and CWR22 tumor-bearing nu/nu mice. We also performed a small-animal PET study of 18F-FAC in CWR22 tumor-bearing nu/nu mice and a whole-body PET study in a baboon to examine defluorination. Results: We obtained 18F-FAC in a radiochemical yield of 55% ± 5% (mean ± SD) in ∼35 min and with a radiochemical purity of >99%. Rat biodistribution showed extensive defluorination, which was not observed in the baboon PET, as indicated by the standardized uptake values (SUVs) (SUVs of iliac bones and femurs were 0.26 and 0.3 at 1 h and 0.22 and 0.4 at 2 h, respectively). CWR22 tumor-bearing nu/nu mice showed tumor uptake (mean ± SD) of 0.78 ± 0.06 %ID/g (injected dose per gram of tissue) for 11C-ACE versus 4.01 ± 0.32 %ID/g for 18F-FAC. For most organs - except blood, muscle, and fat - the tumor-to-organ ratios at 30 min after injection were higher with 18F-FAC, whereas the tumor-to-heart and tumor-to-prostate ratios were similar. Conclusion: All of these data indicate that 18F-FAC may be a useful alternative to 11C-ACE tracer for the detection of prostate tumors by PET.
|Number of pages||9|
|Journal||Journal of Nuclear Medicine|
|State||Published - Mar 1 2007|
- Prostate tumor detection