DISTRIBUTION OF EHDP-TC-99M IN TISSUES OF DOG AND ITS APPLICATION IN ASSESSMENT OF FRACTURE HEALING

Google Scholar
  • 1 January 1977
    • journal article
    • research article
    • Vol. 59  (4) , 322-327
Abstract
Tc-labeled ethane hydroxydiphosphonate (99mTc-EHDP) is a commonly used bone-scanning agent. After injection it leaves the circulation to enter bone and to be cleared by the kidney. The transcapillary exchange of 99mTc-EHDP in bone was examined and found to be low. The capillary movement was compared with that of sucrose, a freely diffusible substance and it was found that the permeability ratio of 99mTc-EHDP to 14C-sucrose was similar to the diffusion coefficient ratio, suggesting that 99mTc-EHDP passes through the capillaries by the process of passive diffusion. The renal clearance of 99mTc-EHDP was 24 ml/min and was unaffected by the action of parathyroid hormone. After a fracture the bone blood flow increases, although the transcapillary extraction of 99mTc-EHDP does not change. This is because there is an increase, from recruitment and dilatation of capillaries, in the surface area available for exchange. The increased isotopic activity seen on a bone scan after a fracture is primarily related to an increase in bone blood supply from capillary enhancement within the cortex.