Technetium[99mTc]Bicisate

Diagnostic aid (brainimaging); radioactive agent.

Technetium(^99mTc) bicisate is a neutral, lipophilic complex that crossesthe blood-brain barrier and is selectively retained in the brain.The kit used to prepare the product contains two vials.
Vial “A” contains the ligand, tin, and other components thatmust be protected from light, whereas vial “B” contains abuffer solution. The radiopharmaceutical is prepared byadding sodium pertechnetate (^99mTc) to the shielded “B” vialcontaining the buffer. The vial A containing lyophilized bicisate,EDTA, mannitol, and stannous chloride is reconstitutedwith 3 mL of normal saline (0.9% NaCl). Within 30seconds, 1 mL of the saline solution from vial A is transferredto vial B and allowed to incubate at room temperaturefor 30 minutes. The tagged product must be used within 6hours of preparation. The structure of the technetium complexis [N,N'-ethylene-di-L-cysteinato(3-)]oxo [^99mTc]technetium(V) diethyl ester.
After intravenous injection of 20 mCi (740 MBq) of Tc-99m bicisate, about 5% of the injected dose is localizedwithin the brain cells 5 minutes after injection. Ester hydrolysistraps the radiotracer within the brain. This radiotraceris indicated for the evaluation of stroke, but it is used offlabelto clinically evaluate various brain disorders, especiallybrain perfusion (“brain death”).