FLUORIDE KINETICS OF THE AXIAL SKELETON MEASURED IN-VIVO WITH FLUORINE-18-FLUORIDE PET

The aim of this study was to quantify regional bone blood flow and inf lux rate with PET and [F-18]fluoride in patients with metabolic bone d isorders. Methods: Dynamic imaging of the spine or pelvis was performe d after administration of 300-370 MBq of F-18(-). Plasma clearance of F-18(-) was determined in blood sampled from the radial artery. A thre e-compartment model was used to estimate the regional flow and fluorid e influx rate. Results: In this preliminary study, fluoride flux (in m u mol/min/liter) could be measured regionally. The flux was consistent with the pathophysiology of the studied metabolic disorders and allow ed the various disease states to be distinguished. Bone blood flow and influx rate were low in osteoporosis (in the ''normal-appearing'' bon e) and high in Paget's disease. Conclusion: With PET and [F-18]fluorid e, local bone blood flow and fluoride influx rate can be quantified in patients in vivo. Metabolically active zones have an increased influx rate and an accordingly increased flow. In principle, this technique permits classification of bone disorders and has potential for the mon itoring of therapy response in metabolic bone disease.