Evaluation of the metabolic response to min therapy in pancreatic cancer xenografts using a clinical PET-CT System

OBJECTIVES: We analyzed the effects of anti-hedgehog signaling on the F-18-FDG uptake of pancreatic cancer xenografts (PCXs) using a clinically implemented positron emission tomography (PET)-computer tomography (CT) scanner with high-resolution reconstruction. METHODS: PCXs from two pancreatic cancer cell lines were developed subcutaneously in nude mice and injected intraperitoneally with a low dose of cyclopamine for 1 week. F-18-FDG PET-CT was performed using a new-generation clinical PET-CT scanner with minor modifications of the scanning protocol to adapt for small-animal imaging. The data set was reconstructed and quantified using a three-dimensional workstation. RESULTS: MiaPaCa-2 cells, which respond to cyclopamine, showed decreased F-18-FDG uptake without a change in tumor size. For hip tumors, the maximum standardized uptake value (SUVmax) was reduced by -24.5 +/- 9.2%, the average SUV (SUVavg) by -33.5 +/- 7.0%, and the minimum SUV (SUVmin) by -54.4 +/- 11.5% (P < .05). For shoulder tumors, SUVmax was reduced by -14.7 +/- 7.5%, SUVavg by -12.6 +/- 6.3, and SUVmin by -30.3 +/- 16.7% (P < .05). Capan-1 cells, which do not respond to cyclopamine, did not show significant SUV changes. CONCLUSIONS: The new generations of clinically implemented PET-CT scanners with high-resolution reconstruction detect a minimal response of PCX to low-dose short-term cyclopamine therapy without changes in tumor size and offer potential for preclinical translational imaging.