Evaluation of the Metabolic Response to Cyclopamine Therapy in Pancreatic Cancer Xenografts Using a Clinical PET-CT System.
OBJECTIVE
We analyzed the effects of anti-hedgehog signaling on the (18)F-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. (18)F-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 (18)F-FDG uptake without a change in tumor size. For hip tumors, the maximum standardized uptake value (SUV(max)) was reduced by -24.5 ± 9.2%, the average SUV (SUV(avg)) by -33.5 ± 7.0%, and the minimum SUV (SUV(min)) by -54.4 ± 11.5% (P < .05). For shoulder tumors, SUV(max) was reduced by -14.7 ± 7.5%, SUV(avg) by -12.6 ± 6.3, and SUV(min) 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.
Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
Hany
H
Kayed
Patrick
P
Meyer
Yong
Y
He
Bettina
B
Kraenzlin
Christian
C
Fink
Norbert
N
Gretz
Stefan O
SO
Schoenberg
Maliha
M
Sadick