Wizard2 link automatic gamma counter

An Inveon microPET/microCT (Siemens Medical Solutions USA, Inc.) was used for PET scanning. Each tumor-bearing mouse was injected with 5–10 MBq of ⁶⁴Cu-NOTA-FSHR-mAb via tail vein and subjected to 5–15 minutes of static PET scans at different chosen time points p.i. Maximum a posteriori (MAP) algorithm was chosen for image reconstruction, adopting no attenuation or scatter correction. Inveon research workshop (IRW) was used to superimpose three-dimensional (3D) regions-of-interest (ROIs) on the tumor and major organs in the decay-corrected whole-body images. The radioactivity in each ROI volume was converted to MBq/g and then divided by the total administered radioactivity to obtain a percentage of injected dose per gram of tissue (%ID/g) for each ROI.
After the last PET scans at 48 h p.i., the mice were euthanized and their blood, CAOV-3/SKOV-3/PC-3/MDA-MB-231 tumors, and major organs/tissues were collected and wet-weighed. The radioactivity in each collected sample was measured using a WIZARD^{2 (link)} automatic gamma-counter (Perkin Elmer) and recorded as %ID/g (mean ± SD).

Biodistribution studies were carried out to correlate the radiotracer uptake based on PET imaging with the quantitative radioactivity distribution data obtained in PC-3 tumor-bearing mice. Following PET imaging at 3.5 h p.i., mice were euthanized and blood, tumor, and major organs/tissues were collected and wet-weighed. The radioactivity in each sample was measured using a WIZARD^{2 (link)} automatic gamma-counter (PerkinElmer) and recorded as % ID/g (mean ± SD). Tumor, liver, spleen, and muscle were also frozen for further histological analysis. A separate group of PC-3 tumor-bearing mice (n = 3) were injected via the tail vein with 0.5–1 MBq of [¹⁸F]3a and sacrificed at 1.5 h after radioligand injection to compare its early organ distribution profile with the data acquired in PET studies. All radioactivity measurements were corrected for radioisotope decay.