Treatment of N,N'-bis(2-hydroxyethyl)ethylenediamine (I) with p-toluenesulfonyl chloride in pyridine afforded the tretratosyl derivative (II). The disodium salt (IV) prepared from tritosyl diethylenetriamine (III) was then condensed with (II) in hot DMF to produce the macrocyclic compound (V). Cleavage of the N-tosyl groups of (V) to afford (VI) was effected by treatment with H2SO4 at 110 C. Quaternization of triethylamine with 1,3-dibromopropane (VII) gave rise to ammonium salt (VIII). Macrocycle (VI) was then alkylated with bromide (VIII) to furnish (IX). Then, complexation of (IX) with 99TcO2 was carried out by treatment with radiolabeled sodium pertechnetate in the presence of SnCl2.