Inveon pet ct system

KPPC mice at 7-9-week-old, KPC mice at 22-23-week old, and their wild type littermates at the same age were anesthetized and injected with 3.7 MBq ⁶⁴Cu-Cu@CuO_x-ECL1i/⁶⁴Cu-Cu@CuO_x-NT in 100 μL saline via the tail vein. Small animal PET scans were carried out on Inveon PET/CT system (Siemens, Malvern, PA) at 24 h post injection (60 min frame). The attenuation, scatter, normalization and camera dead time were all corrected for micro-PET images for co-registration with micro-CT images. The Inveon PET/CT scanner is periodically calibrated using a normalization phantom of known activity concentration to ensure its quantitative accuracy. Micro-PET images were reconstructed with the maximum a posteriori (MAP) algorithm. Data quantification was carried out using Inveon Research Workplace. Tumor accumulation was computed as percent injected dose per gram (%ID/g) of tissue in three-dimensional region-of-interests without the correction for partial volume effect. PET blocking study was done by co-injection of 50-fold non-radioactive Cu@CuO_x-ECL1i/Cu@CuO_x-NT for competition.

Small animal PET imaging was carried at multiple time points (1 h, 4 h, 24 h) post the intravenous injection of ⁶⁴Cu-CuNCs or ⁶⁴Cu-CuNCs-FC131 (approximately 3.7 MBq/100 μL of saline) to determine the dynamic variation of tumor uptake using either a microPET Focus 220 (Siemens, Malvern, PA) or Inveon PET/CT system (Siemens, Malvern, PA), which were cross-calibrated periodically. To determine the effect of blood flow on tumor uptake, ¹⁵O-water (half-life=122.24 s) PET imaging was performed on the PDX mice (n=4) by injecting 22–37 MBq of ¹⁵O-H₂O through tail vein. A 0–10 dynamic scan was acquired immediately after the injection. All the PET images were reconstructed with maximum a posteriori (MAP) algorithm to co-register with CT imaging after the correction of attenuation, scatter, normalization, and camera dead time. Tumor uptake was analyzed using Inveon Research Workplace in three-dimensional regions of interest (ROIs) and presented as percent injected dose per gram (%ID g⁻¹) of tumor tissue. The tumor targeting specificity of ⁶⁴Cu-CuNCs-FC131 was assessed by competitive receptor blocking studies through the co-injection of using 20-fold non-radioactive CuNCs-FC131 along with the radiotracer.^{26 (link)}

The CCR2 (ECL1i: LGTFLKC) and CCR5 (DAPTA: D-A₁STTTNYT) targeting peptides were synthesized from D-form amino acids by CPC Scientific (Sunnyvale, CA). Maleimido-mono-amide-DOTA was purchased from Macrocyclics, Inc (Dallas, TX). DOTA-ECL1i and DOTA-DAPTA was synthesized as reported (Heo et al., 2019 ; Liu et al., 2017 (link); Luehmann et al., 2014 (link)). Probes were radiolabeling with ⁶⁴Copper (⁶⁴Cu). The radiolabeled compound was analyzed using radio-HPLC to ensure more than 95% radiochemical purity prior to animal studies. Mice were anesthetized with isoflurane and injected with 3.7 MBq of ⁶⁴Cu-DOTA-ECL1i or 3.7 MBq ⁶⁴Cu-DOTA-DAPTA in 100 μL of saline via the tail vein. Small animal PET scans (0 to 60 min dynamic scan) were performed on either microPET Focus 220 (Siemens, Malvern, PA) or Inveon PET/CT system (Siemens, Malvern, PA). The microPET images were corrected for attenuation, scatter, normalization, and camera dead time and co-registered with microCT images. All of the PET scanners were cross-calibrated periodically. The microPET images were reconstructed with the maximum a posteriori (MAP) algorithm and analyzed by Inveon Research Workplace. The uptake was calculated as the percent injected dose per gram (%ID/gram) of tissue in three-dimensional regions of interest (ROIs) without the correction for partial volume effect.