Quantitative studies of bone in postmenopausal women using F-18-fluoride and Tc-99m-methylene diphosphonate

G M Blake, S J Park-Holohan, I Fogelman

Research output: Contribution to journalArticlepeer-review


Quantitative radionuclide studies of bone using the short-lived tracers F-18-fluoride and Tc-99m-methylene diphosphonate (MDP) are an alternative method to biochemical markers of bone turnover for investigating the dynamic state of the skeleton. In this study we evaluated their use to quantify bone turnover in women receiving antiresorptive therapy compared with that of untreated control subjects. Methods: The patients were 69 healthy postmenopausal women. Twenty-six women were receiving hormone replacement therapy (HRT) and 43 were untreated age-matched control subjects. After bolus injection of F-18-fluoride (1 MBq), Tc-99m-MDP (1 MBq), Cr-51-ethylenediaminetetraacetic acid (3 MBq), and I-125-labeled human serum albumin (0.25 MBq), multiple blood samples and urine collections were taken between 0 and 4 h. The clearance to bone mineral K-bone was first evaluated using the area under the plasma concentration curve (AUC) on the assumption that the rate constant k(4) for the outflow of tracer from bone was negligibly small. AUC values of K-bone were then compared with those found using a compartmental model method that allowed k(4) to be fitted as a free parameter. Results: Using the AUC method the mean +/- SD for K-bone for the 2 tracers were: F-18-fluoride, 61.8 +/- 12.0 mL . min(-1) (HRT group) versus 67.2 +/- 12.6 mL . min(-1) (control group) (P = 0.045); and Tc-99m-MDP, 40.3 +/- 8.2 mL . min(-1) (HRT group) versus 44.2 +/- 7.6 mL . min(-1) (control group) (P = 0.024). Values for the 2 tracers in individual patients were moderately well correlated (r = 0.76; P <0.001). Using the compartmental model method, k(4) for F-18-fluoride was shown to lie in the range 0-0.0025 min(-1) with a best-fit value of 0.0018 min(-1). Values of K-bone determined using k(4) = 0.0018 min(-1) were highly correlated with the AUC values (r = 0.989; SEE = 2.05 mL . min(-1)) with numeric values that were larger by a factor of 1.53. Analysis of the Tc-99m-MDP data was more difficult because of uncertainties in protein binding in the extracellular fluid compartment space. The best fit for k(4) was in the range 0.0010-0.0014 min(-1) with values of K-bone similar to those found using the AUC method. Conclusion: Values of K-bone determined using the AUC method were able to differentiate between HRT-treated women and postmenopausal women who were not treated and were highly correlated with those determined using a compartmental model method with nonzero values of k(4).
Original languageEnglish
Pages (from-to)338 - 345
Number of pages8
JournalJournal of Nuclear Medicine
Issue number3
Publication statusPublished - 2002


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