Bone imaging agents

HO-P-C-P-OH 1 1 1 HO CH2OH 1 1- Hydroxy- 4- amino- butylidene-1,1- diphosphonate (alendronate) (ABP) 

The [ Tc-diphosphonate] agents are administered to diagnose fracture, bone tumor, metastatic lesion, sarcoma, arthritis, osteomyelitis, and other bone diseases that result in the occurrence of growing bone with readily accessible coordination of calcium in the hydroxyapatite bone structure [132]. The bone scanning is performed 2-3 h post-injection to reduce the background radioactivity in the body. In 24 h 75 to 85 % of the activity is excreted in the urine [84]. 

Very recently another bone imaging agent Tc-ABP], prepared by reduction of 99mTc()4 with SnF2 in the presence of l-hydroxy-4-amino-butylidenc-l,l-diphospho- 

8 Tc-labeled red blood cells ( Tc-RBCs) and white blood cells (WinJc-WBCs) 

White blood cells (WBCs), in particular polymorphonuclear leucocytes and monocytes, accumulate in high concentrations at sites of infection. Radiolabeled leucocytes or granulocytes now are widely established as a means of localizing various forms of 

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Technetium-99m oxidronate is a bone imaging agent used to demonstrate areas of altered osteogenesis. It is rapidly cleared from the blood and taken up in areas of bone that are undergoing osteogenesis. The kit is a vial containing a lyophilized powder where sodium oxidronate is the active... 

Technetium-99m medronate ( Tc methylene diphosphonate) is used as a bone imaging agent to delineate areas of altered osteogenesis. The product is formed by the addition of up to 7.4 GBq (200 mCi) of Tc pertechnetate. 

Until recently it has rarely been possible to definitively characterize the "mTc species present in a radiopharmaceutical formulation because of the extremely low concentrations involved. In some cases, electrophoresis has been used as a means of determining the minimum number of species present. In a recent example a methylene diphosphonate formulation for preparing a "mTc bone imaging agent was found to produce at least four different "mTc species.581 In favourable circumstances it may be possible to determine the net charge on the ionic materials present by this technique. However, such measurements require careful interpretation if erroneous conclusions are to be avoided, and they provide no detailed information relating to chemical structure.20... 

Many of the Tc complexes (16, 17, 19) present the 0x0 Tc =0 + core and are pentacoordinate (square pyramid), but other metal oxidation states and coordination numbers are possible, for instance, in (20) (hexacoordinate with the dioxo Tc 02 " core), in (18) (heptacoordinateTc ), in (21) or (23) (hexacoordinate Tc ), or in (22) (hexacoordinate Tc ). In Tc-diphosphonate radiopharmaceuticals, used as bone imaging agents, the metal is beheved to be in the 4-4 oxidation states. The +1 oxidation state in the homoleptic isocyanide complex (22) is expected to be advantageous in terms of the kinetic inertness associated to its low-spin configuration,... 

Fletcher JW, Solaric Georges E, Heiuy RE, Donato RM (1973) Evaluation of "Tc-pyrophosphate as a bone imaging agent. Radiology 467-469... 

Weber DA, Makler PT Jr, Watson EE, Coffey JL, Thomas SR, London J (1989) Radiation absorbed dose from technetium-99m-labeled bone imaging agents MIRD dose estimate report no 13. J Nucl Med 30 1117-1122... 

Djokiffi et al. have investigated yttrium-90-labeling of the 2,3-dicarbox-ypropane-l,l-diphosphonic acid (DPD), which is currently labeled with technetium-99m and as a Tc DPD clinically used as bone imaging agent. With high skeletal uptake, a minimum uptake in soft tissues and rapid blood clearance, the Y-DPD complex proved to be an excellent candidate for targeting tumor therapy. 

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