Inveon dedicated small animal pet scanner

All animals were starved for 6 h prior to the FDG injection. For injections, the animals were anesthetized with 1.5% isoflurane (Abbott, Wiesbaden, Germany) evaporated in oxygen at a flow rate of 0.5 L/min. Immediately before the injection of FDG, the blood glucose levels were determined by retro-orbital blood draw with a Hemocue 201 (Radiometer GmbH, Willich, Germany), and body weights of the mice were measured. In total, ~13 MBq FDG dissolved in 150 µL NaCl solution was injected i.v., and the animals were kept under isoflurane narcosis for 55 min. postinjection. All animals were warmed during the uptake period. PET scans were performed on an Inveon dedicated small-animal PET scanner (Siemens Preclinical Solutions, Knoxville, USA) for 10 min. while the mice were still under isoflurane narcosis. According to our standard protocol for mouse PET imaging, no attenuation and scatter correction were applied. Reconstruction was performed in Inveon Acquisition Workplace 1.5.0.28 with OSEM2D with four iterations. The reconstructed voxel size was 0.776 × 0.776 × 0.796 mm³.

Approximately 2–4 days after the first detection of liver metastases by micro-CT imaging, animals were given a tail vein injection of ∼13 MBq of ⁶⁴Cu-labeled anti-CEA mAb M5A-DOTA or anti-GD2 mAb hu14.18-DOTA (∼20 µg). For the blocking experiments, 500 µg of unlabeled M5A antibody was injected 3 h prior to the injection of ⁶⁴Cu-labeled M5A antibody.
Ten-minute static PET scans were obtained at 3, 24 and 48 h after tracer injection on an Inveon dedicated small animal PET scanner (Siemens Preclinical Solutions, Knoxville, Tennessee, USA). Animals were anesthetized with 1.5% isoflurane (Abbott, Wiesbaden, Germany) evaporated in oxygen at a flow of 0.5 L/min, and body temperature was maintained at 37°C by a heating pad and a rectal temperature sensor. Images were reconstructed with an iterative ordered-subset expectation maximization algorithm. According to our standard protocol for mouse PET imaging, attenuation and scatter correction were not applied. Images were reconstructed in Inveon Acquisition Workplace 1.5.0.28 with OSEM2D with four iterations. The reconstructed voxel size was 0.776×0.776×0.796 mm. After each PET scan, the animals were transferred to a 7 T ClinScan MR scanner (Bruker, Ettlingen, Germany), and anatomic images were acquired with a 3D turbo-spin-echo (tse) sequence (TE = 205 ms, TR = 3000 ms, voxel size: 0.22×0.22×0.22 mm³, matrix size: 160×256×120).