Is v1.4.3 sp1

¹⁸F-FDG was synthesized according to the method developed by Ido [21 (link)] to a purity of > 95% in the Jiangsu Atomic Energy Laboratory (Jiangsu, China). Micro-PET images were acquired with an Inveon PET scanner (Siemens Preclinical Solutions, LLC, Knoxville, TN, USA). Before scanning, rats were fasted for 8–12 h, after which 7.4–11.1 MBq of ¹⁸F-FDG was injected via the tail vein and PET scans were obtained 60 min later. Anesthesia was maintained during the PET scans with 1.5% isoflurane in 100% oxygen at 1.5 L/min. For the scans, rats were placed prone on the bed of micro-PET, and the limbs were fixed with tape. A 10-min static single-frame scan was acquired with a small-animal PET camera, and images were reconstructed by ordered subsets expectation maximization (OSEM)-3D IAW (Siemens Preclinical Solutions).
Two experienced nuclear medicine physicians examined all PET images in a double-blinded fashion. Regions of interest (ROIs) in the right lungs were drawn using vendor software (IS_v1.4.3 SP1; Siemens Healthineers, Erlangen, Germany). The SUV was calculated as an absolute measure of ¹⁸F-FDG uptake in an ROI as:
[(measured activity concentration, in kBq/mL)/(injected dose, in kBq/body weight, in g)].
All animals were weighed before scanning. SUV_max and SUV_mean were defined as the maximum and mean tracer uptake in the ROIs.

A lyophilized kit for labeling the PRGD2 peptide purchased from the Jiangsu Institute of Nuclear Medicine was employed according to a previously published study (15 (link)). The radiochemical purity of ¹⁸F−RGD exceeded 95%, and its specific radioactivity exceeded 37 GBq (1,000 mCi)/µmol. All micro-PET images were obtained with an Inveon PET scanner (Siemens Preclinical Solutions, LLC, Knoxville, TN, USA) using ¹⁸F−RGD. With the assistance of the positioning laser from the Inveon system, each tumor-bearing mouse was placed with its tumor located in the center of the field of view to achieve the highest imaging sensitivity. ¹⁸F-RGD PET scans were performed 60 min after tail-vein injection of ¹⁸F−RGD (2.4−3.5 MBq) under isoflurane anesthesia with 1.5% isoflurane in 100% oxygen at a flow rate of 1.5 L/min. The PET scans were acquired on a combined PET/CT scanner for 5 min per field of view. The PET images were reconstructed and analyzed using the OSEM−3D IAM software program (IS_v1.4.3 SP1; Siemens Preclinical Solutions, LLC).

For each PET scan, regions of interest were drawn over the tumor using vendor software (IS_v1.4.3 SP1; Siemens Medical Solutions) on decay-corrected whole-body coronal images slice by slice. Two experienced nuclear medicine physicians read all of the images through consensus reading. PET images in the tumor were first evaluated by visual analysis, and then a quantitative analysis was performed by determining the SUV. Every of the outlined slices for each tumor was divided into outer, middle, and inner layers based on the luminance signal in the coronal plane by the images (Fig. 5). Then ROI was positioned around the tumor area of interest slice by slice and obtained a set of data such as ROImax, mean. The SUVs were calculated according to the following formula: [measured activity concentration (Bq/mL) × body weight (g)]/injected activity (Bq).