The role of skeletal blood flow in determining the uptake of 99mTc-methylene diphosphonate.

The increased uptake of bone-seeking radionuclides following a fracture has been stated to be due to an increase in bone blood flow, resulting in an increase in capillary surface area available for exchange. This paper examines the relationship between the maximum instantaneous extraction of 99mTc-MDP and blood flow in normal canine tibia. The findings, consistent with the model of capillary action proposed for muscle by Renkin and Crone, are applicable to bone. There is no evidence that in normal bone the surface area available for exchange responds to an increase in bone blood flow.