Discovery 790 elite

PET/CT imaging of tumor-bearing mice was performed on a clinical time-of-flight (TOF) 64-slice PET/Computed tomography (CT) scanner (Discovery 790 Elite, GE healthcare). The mice bearing tumors (for each group n = 4) were injected with 3.7 MBq (100 μCi) of ¹⁸F-IRS into the tail vein. At 30 min, 60 min and 120 min after injection, the mice were anesthetized with 2% isoflurane and placed near the center of the field of view of the PET/CT scanner in prone position. For blocking studies, gefitinib (100 mg/kg) was injected into HCC827 xenografts nude mice (n = 4) via tail vein 60 min before PET/CT imaging. The mice were imaged as described above 120 min after injection.
The images were reconstructed using a two-dimensional ordered-subset expectation maximization (OSEM) algorithm. For each scan, regions of interest (ROIs) were drawn over the tumor and major organs using the AW4.6 software (GE Healthcare) on decay-corrected whole-body coronal images. The radioactivity concentrations (accumulations) within the tumor, muscle were obtained from mean pixel values within the multiple ROI volumes and then converted to megabecquerels per milliliter per minute using the calibration factor determined for the PET system. These values were then divided by the administered activity to obtain (assuming a tissue density of 1 g/ml) an image ROI-derived percent injected dose per gram (% ID/g).

All patients involved in this study had ¹⁸F-FDG PET/CT imaging. Image acquisition parameters for each cohort are presented in Supplementary Table 11. Since uptake of EGFR-TKI PD153035 based on ¹⁸F-MPG is highly correlated with EGFR mutation status^{15 (link),29 (link),30 (link)}, ¹⁸F-MPG PET/CT imaging (Discovery 790 Elite; GE Healthcare) was also performed on HMU cohort. Scanning was initiated 1 h after administration of ~259 MBq of ¹⁸F-MPG. Whole-body CT scans were firstly acquired for attenuation correction by using a low-dose protocol (40 mA, 120 keV), and PET data were subsequently acquired in 3D mode. The anisotropic resolutions for CT and PET images were 0.98 × 0.98 × 3.75 mm³ and 3.65 × 3.65 × 3.27 mm³, respectively^{15 (link)}.
All PET images were converted into SUV units by normalizing the activity concentration to the dosage of ¹⁸F-FDG injected and the patient body weight after decay correction, and all CT images were converted into lung window.