Measurement of 24-hr whole-body retention of sup(99m)Tc-MDP with a thyroid uptake probe

A new method for measurement of 24-hr whole-body retention (WBR) of sup(99m)Tc-MDP, using a thyroid uptake probe was established and its clinical significance was evaluated in various bone diseases. (1) Reproducibility of 24-hr WBR in 9 patients was very good. Correlation coefficient was 0.997 and coefficient of variability was only 1.83%. (2) Radiochemical purity of sup(99m)Tc-MDP was 97.8 +- 0.7% (n = 5), indicating no significant inter-lot variations. (3) 24-hr WBR of normal adult males (n = 5) was 30.0 +- 4.9%, which was significantly elevated compared to the reported sup(99m)Tc-HEDP WBR of 19.2 +- 1.7%. Whole-body retentions of chronic renal failure, metastatic bone disease and hyperthyroidism groups were significantly elevated compared to that of the normal group. However, WBR of steroid-induced osteoporotic group was significantly decreased. Based on these results, this thyroid uptake probe method was simple, reproducible and accurate to measure 24-hr WBR of sup(99m)Tc-MDP. Quantification of WBR of sup(99m)Tc-MDP was of great clinical value to diagnose metabolic bone disease and to follow-up metabolic and metastatic bone diseases. (author)