Synthesis and biodistribution of a new 99mTc nitrido complex for brain imaging

Bis(N-isobutyl-dithiocarbamato) nitrido technetium-99m complex [99mTcN(IBDTC)2] (IBDTC: N-isobutyl dithiocarbamato) was synthesized by the reduction of 99mTcO4- into [99mTc = N]2+ with stannous chloride in the presence of succinic dihydrazide and propylenediamine tetraacetic acid, followed by the addition of sodium N-isobutyl dithiocarbamate dihydrate. The radiochemical purity of the complex was over 90% as measured by thin layer chromatography. It was stable over 6h at room temperature. Its partition coefficient indicated that it is a good lipophilic complex. Biodistribution in mice demonstrated that the complex accumulated in the brain with high uptake and good retention. The brain uptake (ID%/g) was 6.22, 5.45 and 3.88 and the brain/blood ratio was 1.51, 2.24, 1.84 at 5, 30 and 60 min post-injection, respectively. These results suggest potential usefulness of the complex as a brain perfusion imaging agent.