Assessment of blood pool, soft tissue, and skeletal uptake of sodium fluoride F 18 with positron emission tomography-computed tomography in four clinically normal dogs.

Objective: To determine the ideal interval to image acquisition after IV injection of sodium fluoride F 18 ((18)F-NaF) and evaluate biodistribution of the radiopharmaceutical in clinically normal skeletally immature dogs.

Animals: 4 female dogs.

Procedures: Each dog was anesthetized for evaluation with a commercial hybrid positron emission tomography (PET)-CT instrument. A low-radiation dose, whole-body CT scan was acquired first. An IV injection of (18)F-NaF (0.14 mCi/kg) was administered, and a dynamic PET scan centered over the heart and liver was acquired during a period of 120 minutes. Uptake of (18)F-NaF in the blood pool, soft tissues, and skeletal structures was evaluated via region of interest analysis to derive standardized uptake values and time-activity curves, which were used to determine the optimal postinjection time for skeletal image acquisition. Biodistribution was also assessed from a final whole-body PET-CT scan acquired after the dynamic scan.

Results: Time-activity curves revealed a rapid decrease in the amount of radiopharmaceutical in the blood pool and soft tissues and a rapid increase in the amount of radiopharmaceutical in bones soon after injection. At 50 minutes after injection, the greatest difference in uptake between soft tissues and bones was detected, with continued subtle increase in uptake in the bones. Uptake of (18)F-NaF was slightly increased at growth plates and open ossification centers, compared with that at other parts of the bone.

Conclusions And Clinical Relevance: At 50 minutes after IV injection of (18)F-NaF at the dose evaluated, PET-CT yielded excellent bone-to-background ratio images for evaluation of the skeletal system in dogs.