Chest PET-CT was performed at baseline prior to antigen recall (D0) and on days 3 (D3) and 7 (D7) post recall. Animals were fasted for at least 8 h before each imaging session. All imaging acquisition was performed using the Digital Photon Counting (DPC) PET-CT system (Vereos-Ingenuity, Philips) implemented in a BSL-3 laboratory. These sessions were always performed in the same experimental conditions (acquisition time and animal order) to limit [18F]-FDG-PET experimental bias. Animals were first anesthetized with ketamine hydrochloride (5 mg/kg, IM) associated with medetomidine hydrochloride (0.05mg/kg IM), intubated, and then maintained under 0.5–1.5% isoflurane and placed in a supine position on a warming blanket (Bear Hugger, 3M) on the machine bed with monitoring of the cardiac rate, oxygen saturation, and body temperature.
Computed Tomography (CT) was performed 5 minutes prior to PET acquisition for attenuation correction and anatomical localization. The CT detector collimation used was 64 × 0.6 mm, the tube voltage was 120 kV, and the intensity was approximately 150 mAs. Chest-CT images were reconstructed with a slice thickness of 1.25 mm and an interval of 0.63 mm. A whole-body PET scan (3 bed positions, 3 min/bed position) was performed approximately 45 min post-injection of 3.5 ± 0.4 MBq kg-1 of [18F]-FDG via the saphenous vein. PET images were reconstructed onto a 256 × 256 matrix using OSEM (3 iterations, 15 subsets). After PET acquisition, animals were resuscitate using atipamezole hydrochloride (0.25mg/kg).
PET images were analyzed using 3DSlicer software (open-source tool). For segmentation, various regions of interest (entire lung and separated lung lobes) were semi-automatically contoured according to anatomical information from CT. A 3D volume of interest (VOI) was interpolated from several ROIs in different image slices to cover each lung lobe excluding background signal (heart and liver). For quantification, [18F]-FDG accumulation in the VOIs was given as a standardized uptake value (SUVmean, SUVmax).
Computed Tomography (CT) was performed 5 minutes prior to PET acquisition for attenuation correction and anatomical localization. The CT detector collimation used was 64 × 0.6 mm, the tube voltage was 120 kV, and the intensity was approximately 150 mAs. Chest-CT images were reconstructed with a slice thickness of 1.25 mm and an interval of 0.63 mm. A whole-body PET scan (3 bed positions, 3 min/bed position) was performed approximately 45 min post-injection of 3.5 ± 0.4 MBq kg-1 of [18F]-FDG via the saphenous vein. PET images were reconstructed onto a 256 × 256 matrix using OSEM (3 iterations, 15 subsets). After PET acquisition, animals were resuscitate using atipamezole hydrochloride (0.25mg/kg).
PET images were analyzed using 3DSlicer software (open-source tool). For segmentation, various regions of interest (entire lung and separated lung lobes) were semi-automatically contoured according to anatomical information from CT. A 3D volume of interest (VOI) was interpolated from several ROIs in different image slices to cover each lung lobe excluding background signal (heart and liver). For quantification, [18F]-FDG accumulation in the VOIs was given as a standardized uptake value (SUVmean, SUVmax).
