1977 Volume 26 Issue 6 Pages 382-388
The deposition of 99mTc-methylene diphosphonate (MDP) in the bone compared with that of 99mTc-EHDP was studied from basic and clinical aspects. Yields and stability of the labels were studied by paperchromatography and thin-layer chromatography. Rabbits experiments included the scintimetry of the bone, kidney, and soft tissue by setting ROI five to 60 minutes after administering labels, scintigraphy for two and three hours after the administration of labels, and distribution studies three hours after administration.
In the clinical study the ratios of blood radioactivity 2 hours after administration to that 10 minutes later in the cases of malignant and benign bone diseases were estimated, and the observations were made of the scintigraphy two hours after the administration of labels. Also, the scintimetry was done of pathological bones, normal bone, kidney and soft tissue region.
The labeling yield and stability of MDP have been found to be about the same as with EHDP, proving it to be quite satisfactory. A large fraction of the activity of MDP and EHDP was cleared rapidly from the blood stream, but the percentage remaining in blood three hours after administration is less with MDP. The deposition in the rabbit bone as observed by scintimetry could be recognized quite early with both MDP and EH DP, and what is more, a practically same level has been seen up to the one-hour observation. Though the ratios of radioactivity of kidney and soft tissue to bone increased gradually due to the gradual decrease of radioactivity in the kidney and soft tissue, MDP showed higher level.
When the bone accumulation as estimated by radioassay was represented by percent dose/1% body weight, it became MDP: 4.804, EHDP: 3.521. The bone to organ ratios were greater with MDP. By the MDP-scintigraphy of bone diseases two hours after its administration the lesion could be clearly delineated, and scintimetry ratios were superior to those by EHDP. The above findings suggest that MDP is an excellent bone scanning agent.
