Inveon small animal pet system

Seven rabbits (body weight 3.33 ± 0.17 kg) were injected with 18 F-FEDAC (251 ± 27 MBq) via the auricular vein 3 h before PET imaging. The rabbits were placed under isoflurane anesthesia (1.5-2.0%), and PET was conducted for 30 min using an Inveon small-animal PET system (Siemens Medical Solutions, Malvern, PA, USA), followed by contrastenhanced computed tomography (CE-CT) (CosmoScan GXII, Rigaku, Tokyo, Japan). PET images were reconstructed using a 3D maximum a posteriori algorithm (18 iterations with 16 subsets) without attenuation correction. The region of interest was manually drawn over the blood vessels, and tracer uptake was quantified in terms of standardized uptake value (SUV) using the reconstructed PET images. For CE-CT, a contrast agent was injected intravenously (3 mL/kg iopamidol with 370 mg/mL iodine; Oiparomin 370, Fuji Pharmaceutical Co., Toyama, Japan), and blood vessels were imaged 20 s after injection. CT images were acquired with an X-ray source set at 90 kVp and 200 μA using a small-animal CT system (CosmoScan GXII, Rigaku, Tokyo, Japan) and were reconstructed using a filtered back-projection algorithm for cone beam.

Animals were injected with 12-15 MBq (for PET) or 5-7 MBq (for biodistribution studies) of the radiotracers under isoflurane anesthesia and subsequently allowed to wake up with access to food and water. For blockade, 60 nmol of the respective unlabeled compound was administered 10 min before tracer injection. For biodistribution, animals were sacrificed after 90 min, and organs were harvested and weighed and the activity contained therein counted in a g-counter (Perkin-Elmer). The injected dose per gram of tissue was calculated from organ weights and counted activities, based on individually administered doses. PET was recorded under isoflurane anesthesia 60 or 75 min after injection for 20 min on a Siemens Inveon small-animal PET system. Images were reconstructed as single frames with Siemens Inveon software, using a 3dimensional ordered-subset expectation maximum algorithm without scatter and attenuation correction.