Woodchucks with an average weight of 3.5 kg were too large to fit into our microPET scanner and were placed prone in our clinical Ingenuity PET/CT scanner (Philips, Cleveland, OH) instead. Under 3% isoflurane gas anesthesia, the animals had a low-dose CT scan first, followed by i.v. injection of 37 ~ 56 MBq (1.0 ~ 1.5 mCi) ZD2-(68Ga-NOTA) via the implanted venous access port. A dynamic PET acquisition in list mode started upon injection and lasted 60 min. The PET acquisition was re-binned into a total of 21 frames: 10×30 seconds, 5 X 1-min, 2 X 5-min frames, and 4×10 min, respectively, and reconstructed using iterative 3D-OSEM provided by the vendor incorporating the built-in CT-based attenuation correction. After the scan, the animals were euthanized for tissue harvesting including tumor and matched liver tissues. Some samples were fresh-frozen immediately for later use in PCR or Western blot, while others were fixed with formaldehyde for histology.
Standardized Uptake Value (SUV, normalized radiotracer uptake by body weight and injected tracer dose)35 (link) was calculated for regions of interest (ROIs) defined over focal uptakes of the ZD2 ligand as well as a nearby ROI over the liver background away from focal uptakes, similar to that used for computing FDG uptake.36 (link) Time activity curves in the unit of SUV were generated for these ROIs.
Standardized Uptake Value (SUV, normalized radiotracer uptake by body weight and injected tracer dose)35 (link) was calculated for regions of interest (ROIs) defined over focal uptakes of the ZD2 ligand as well as a nearby ROI over the liver background away from focal uptakes, similar to that used for computing FDG uptake.36 (link) Time activity curves in the unit of SUV were generated for these ROIs.