Technetium imaging agents

The development of the instant radiopharmaceutical kit in the 1970s was followed by the development of technetium imaging agents for renal, skeletal, and hepatobiliary imaging. At that time, the coordination chemistry of technetium was not well understood and as a result, the early radiopharmaceuticals are not fully characterized. Studies of the coordination chemistry of technetium intensified in the late 1970s leading to the discovery of Tc brain, heart, and renal agents. These... 

The early technetium imaging agents have been reviewed in earlier versions of this Encyclopedia and in other references. This section is intended to be an overview highlighting developments in technetium chemistry. 

Figure 4 Structures of clinically useful technetium imaging agents...

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 teboroxime is a myocardial imaging agent and is excreted primarily by the hepatobiliary system. It is rapidly taken up by the myocardium and mosdy washes out within 30 minutes. Imaging protocols are performed immediately after injection. The product is a lyopbili ed mixture of boronic acid, dioxine, and other excipients, and the agent is formed with a beating step. 

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. 

Technetium-99m mertiatide (A/-[Ai-[A/-[(benzoylthio)acetyl]glycyl]glycine) is a renal imaging agent. It is excreted by the kidneys via active tubular secretion and glomerular filtration. The kit vial is reconstituted by using 740—3700 MBq (20—100 mCi) of Tc pertechnetate and boiling for 10 minutes. 

Technetium-99m bicisate is a brain imaging agent that is used for localization of stroke. The lyopbilized kit contains ethyl cysteine dimer as the active ingredient. 

Mousa SA, Bozarth JM, Edwards S et al (1998) Novel technetium 99m-labeled GPIIb/IIIa receptor antagonists as potential imaging agents for venous and arterial thrombosis. Coron Artery Dis 9 131-141... 

Archer CM, Edwards B, Kelly JD, King AC, Burke JF, Riley ALM (1994) Technetium labelled agents for imaging tissue hypoxia in vivo, 4th International Symposium on Technetium and Rhenium in Chemistry and Nuclear Medicine, Bressanone, Italy, September 12-14... 

Technetium and rhenium coordination chemistry has actively developed in order to design materials as potential radiopharmaceuticals diagnostic imaging agents for technetium and potential therapeutic reagents based on rhenium. Continuous efforts are still applied to find efficient chelating systems for the [MO]3+ cores (M=Tc, Re). Thus several complexes with monodentate and... 

Meltzer, P. C.,Blundell, P., Jones,A. G. etal. A technetium-99m SPECT imaging agent which targets the dopamine transporter in primate brain. J. Med. Chem. 40 1835-1844, 1997. 

Figure 7.15 The P280 thrombus imaging agent peptide for labeling with technetium-99m. Possible Tc ligand atoms shown in hold type. (Adapted with permission from Figure 23 of Liu, S. Edwards, D. S. Chem. R(.v., 1999, 99(9), 2235-2268. Copyright 1999, American Chemical Society.)...

Technetium-labeled peptides and proteins have been investigated as potential thrombus-imaging agents. Complex 70, which combines 99mTc with the tripeptide motif Arg-Gly-Asp, binds GP Iib/IIIa recep-... 

---