Quantitative PET Imaging of Tumor CD105

PET scans and image reconstruction (maximum a posteriori (MAP) algorithm, no attenuation or scatter correction) were performed using a microPET/microCT Inveon rodent model scanner (Siemens Medical Solutions USA, Inc.) at various time points postinjection (p.i.) as described previously.^{38 (link)–40 (link)} After each scan, region-of-interest (ROI) analyses were conducted in each mouse with Inveon Research Workplace. ⁶⁴Cu-labeled targeted or nontargeted micelles were injected into each tumor-bearing mouse via the tail vein at a dose of 5 to 10 MBq per mouse before 3 to 15 min static PET scans were performed. Quantitative data were shown as percent injected dose per gram of tissue (%ID/g). For the competitive binding studies, one mg of competing TRC105 antibody was preinjected into four 4T1 tumor-bearing mice one hour before the ⁶⁴Cu-labeled targeted micelles was administered to the mice in order to further assess the CD105 specificity in vivo. Biodistribution studies (mean ± SD) were conducted after the last PET scans using a gamma-counter (Perkin-Elmer) in order to validate the PET analysis.