Abstract
1356
Objectives The value of PET imaging for liver cancer applications is not entirely clear. Previous clinical studies demonstrated that FDG showed uptake mostly in poorly-differentiated hepatocellular carcinoma (HCC) while acetate showed uptake mostly in well- and moderately-differentiated HCCs. Pre-imaging fasting is required for clinical PET imaging with FDG. No studies were done to test the effect of fasting on acetate uptake in HCC for PET imaging. We investigated this situation with a woodchuck model of viral infection-induced HCC.
Methods Four tumor-bearing and one control woodchucks were involved in this study. They were first imaged by PET in fed state followed by another imaging session one week later when they were fasted over-night. For each PET session, 1.0 mCi (37 MBq) of [11C]-acetate was injected i.v., and two tumor-bearing animals had a 30-minute dynamic scan, and one control and the others two tumor-bearing animals only had static scans at 25 or 30 minutes after tracer injection. For those animals that underwent dynamic scans, 1.5 mCi (55.5 MBq) of [18F]-FDG was injected about 100 minutes after acetate injection and a static scan was acquired 55 minutes post FDG injection. After imaging studies, animals were sacrificed, and their liver excised for histology. Standardized Uptake Value (SUV) was calculated using a region of interest (ROI) placed on each tumor with focal uptake.
Results Acetate showed uptake in HCC lesions in all tumor-bearing animals when they were either fasted or fed; some of the tumors were histologically confirmed as well-differentiated HCC while others were confirmed as moderately- or poorly-differentiated HCC; no focal uptake was found in the control animal. Uptake of FDG was shown in different spot of the tumor that was later identified as poorly-differentiation, and only when the animal was fasted. Similar SUVs of acetate in a HCC lesion were obtained, fasted or fed.
Conclusions This study suggested that fasting or not has little impact on acetate PET imaging of HCC. Human studies are needed to validate the findings from this pre-clinical investigation.
Research Support NIH/NCI CA095307