An In Vivo PET Imaging Technique to Detect Tumors in a Murine Model Using Radiolabeled Antibodies

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. In Vivo PET Imaging with ⁸⁹Zr-DFO-J591

CAUTION: This step of the protocol involves the handling and manipulation of radioactivity. Before performing these steps, researchers should consult with their home institution's Radiation Safety Department. All possible steps should be taken to minimize exposure to ionizing radiation.

1. In male athymic nude mice, subcutaneously implant 5 x 10⁶ lymph node carcinoma of the prostate (LNCaP) cancer cells and allow these to grow to a 100-150 mm³ xenograft (3-4 weeks after inoculation).
2. Dilute the ⁸⁹Zr-DFO-J591 radioimmunoconjugate to a concentration of 1.0 mCi/ml in 0.9% sterile saline.
3. Inject 200 µl of the ⁸⁹Zr-DFO-J591 (DFO = desferrioxamine, J591 =  prostate-specific membrane antigen [PSMA] targeting antibody) solution (200 µCi; 7.4 MBq) into the lateral tail vein of the xenograft-bearing mice.
4. At the desired imaging time point (e.g., 12, 24, 48, 72, 96, or 120 hr post-injection), anesthetize the mouse with a 2% isoflurane: oxygen gas mixture.
5. Place the mouse on the bed of the small animal PET scanner and maintain anesthesia during the scan using a 1% isoflurane: oxygen gas mixture. Prior to placing the animal on the scanner bed, verify anesthesia using the toe-pinch method and apply ophthalmic ointment to the eyes of the mouse to prevent drying during anesthesia.
6. Acquire the PET data for the mouse via a static scan with a minimum of 40 million coincident events using an energy window of 350-700 keV and a coincidence timing window of 6 nsec.
7. After completing the acquisition of the image, do not leave the mouse unattended, and do not place it in a cage with other mice until it has regained consciousness.