Inveon micropet microct rodent model scanner

For labelling, 37 MBq of ⁶⁴CuCl₂ was diluted in 300 µL of 0.1 M sodium acetate (pH 5.5) and added to 400 OD₈₆₀ ONc nanonaps for 30 minutes at 37 °C. The ⁶⁴Cu-nanonaps were purified by centrifugal filtration and re-suspended in 500 µL of PBS for further use. For in vitro stability, one OD₈₆₀ of ⁶⁴Cu-nanonaps was re-suspended in 1 mL of SGF or SIF and incubated at 37 °C with stirring. Portions of the mixture (50 µL) were sampled at different time points and washed by centrifugal filtration for analysis. Radioactivity was measured by a Wizard2 gamma counter (Perkin Elmer).
PET scans were performed using an Inveon microPET/microCT rodent model scanner (Siemens). After overnight fasting, each BALB/c mouse was gavaged ~7.4 MBq of ⁶⁴Cu-nanonaps (100 OD₈₆₀). 5–10 minute static PET scans were performed at various time points post-injection. Images were reconstructed using a maximum a posteriori algorithm without scatter correction. After 24 hours mice were euthanized and biodistribution was measured with gamma-counting.

PET scans, image reconstruction, and ROI analysis of each PET scan were performed using an Inveon microPET/microCT rodent model scanner (Siemens Medical Solutions USA, Inc.) as described previously (20 (link)). Each tumor-bearing mouse was intravenously injected with 5–10 MBq of ⁶⁴Cu-NOTA-rh-HGF and 5- to 10-min static PET scans were performed at various time points post-injection (p.i.). The tracer uptake was calculated as percentage injected dose per gram of tissue (%ID/g) (mean ± SD; ≥3 mice per group).
Denature studies were carried out to evaluate c-Met specificity of ⁶⁴Cu-NOTA-rh-HGF in vivo, where a group of 3 mice were each injected with 5–10 MBq of sonicated-denatured tracer, ⁶⁴Cu-NOTA-dnrh-HGF. Biodistribution studies were performed after the last PET scans at 24 h p.i. to validate the PET data. The tumors, liver and muscle were also frozen and cryosectioned for histologic analysis. Quantitative data were expressed as mean ± SD. Means were compared using the Student t test. P values of less than 0.05 were considered statistically significant.

Mice were injected intravenously with 5 – 10 MBq of the tracer (⁸⁹Zr-Df-nivolumab) prior to PET imaging. For imaging, mice were placed in supine position in the Inveon microPET/microCT rodent model scanner (Siemens Medical Solutions, Erlangen, Germany). Scans were performed with 40-million coincidence events static scans being recorded. Images were reconstructed using the 3D ordered subset expectation maximization algorithm and quantified via region-of-interest (ROI) analysis in the Inveon Research Workplace software (Siemens Medical Solutions). Signal quantification was expressed as the percentage of injected dose per gram of tissue (%ID/g).

Small animal PET scans were performed on Inveon microPET/microCT rodent model scanner (Siemens Medical Solutions USA, Inc.). Each 4T1 tumor-bearing mouse was injected intravenously with 5–10 MBq of the radio-labeled polymer conjugate and static PET scans were performed at 0.5, 3, 6, 20, 48 and 72 h post-injection (p.i.). The images were reconstructed using a maximum a posteriori (MAP) algorithm, with no attenuation or scatter correction, and are presented as maximum intensity projections (MIP). For each microPET scan, three-dimensional (3D) regions-of-interest (ROIs) were drawn over the tumor and major organs by using vendor software (Inveon Research Workplace) on decay-corrected whole-body images, and are presented as percentage of injected dose per gram (%ID/g). The data obtained from the ROI analysis were used to construct the time-activity-curves (TAC) for the tumor and other major organs.
Ex vivo biodistribution studies were carried out after the final PET scan at 72 h p.i. to confirm that the quantitative values based on PET imaging truly represented the radioactivity distribution in tumor-bearing mice. The mice were euthanized and blood, 4T1 tumor, and major organs/tissues were collected and wet-weighed. The radioactivity in the tissue was measured using a gamma-counter (Perkin Elmer) and presented as %ID/g (mean ± SD).

For PET imaging, animal studies were carried out in accordance with the University of Wisconsin-Madison Institutional Animal Care and Use Committee. For tumor PET imaging studies, 1 × 10⁶ 4T1 murine breast cancer cells suspended in 30 μL of PBS were injected in the fourth mammary pad of 5–6 week old female BALB/c mice (Envigo, IN). Tumor sizes were monitored regularly, and mice were used when the tumors reached ~7 mm in diameter, typically 7–10 days post-inoculation. Twenty-five OD of ⁶⁴Cu-labeled Pheo nanoparticles was injected intravenously in 4T1 tumor-bearing mice via the tail vein (n = 3). Static positron emission tomography (PET) images were acquired at different time points postinjection (p.i.) on an Inveon microPET/microCT rodent model scanner (Siemens Medical Solutions USA, Inc.). All PET images were reconstructed using a maximum a posteriori algorithm, without attenuation or scatter correction, and analyzed with Inveon Research Workplace software after decay correction. All data are presented as a percentage injected dose per gram (%ID/g). Mice were euthanized after the final PET scans at 72 h postinjection, and ex vivo biodistribution studies were performed, to validate the in vivo results. Blood, tumor, and major organs were collected and wet-weighed, and radioactivity in each tissue was measured on a WIZARD^{2 (link)}γ counter (PerkinElmer) and presented as %ID/g.

U87MG tumor-bearing mice were each intravenously injected with 5-10 MBq of ⁶⁴Cu-NOTA-GO-VEGF₁₂₁ or ⁶⁴Cu-NOTA-GO via tail vein. Serial PET scans were performed at various time points post-injection (p.i.) with using a micro PET/micro CT Inveon rodent model scanner (Siemens Medical Solutions USA, Inc.). Data acquisition, image re-construction, and ROI analysis of the PET data were performed as described previously [26 (link), 31 (link)]. Quantitative PET data of the U87MG tumor and major organs was presented as %ID/g. After the last scan at 48 h p.i., biodistribution studies were carried out to confirm that the %ID/g values based on PET imaging truly represented the radioactivity distribution in mice. Mice were euthanized and U87MG tumor, blood and major organs/tissues were collected and wet-weighed. The radioactivity in the tissue was measured using a γ counter (PerkinElmer) and presented as %ID/g (mean ± SD).