The aim of this study is to examine the influence on biodistribution by introducing the [ 99m Tc≡N] 2+ core into the complex so as to explore a new radiopharmaceutical. 99m TcN-IBDTC (IBDTC:N-isobutyl dithiocarbamate) was prepared through a two-step ligand-exchange reaction by using SnCl 2·2H 2O as reduction agent and SDH (succinic dihydrazide) as a donor of nitride nitrogen atom (N 3- ) at room temperature. The ligand IBDTC was labelled with 99m TcO - 4 directly by using FSA (Formamidine sulfinic acid) as reducing agent. The radiochemical purity of the 99m TcN-IBDTC and 99m Tc-IBDTC complex were both over 90% by TLC. The biodistribution results in mice indicated that 99m TcN-IBDTC had high brain uptake and good brain retention. The brain uptake (%ID·g -1 ) was 6.22

5.45 and 3.88 and the brain/blood ratios were 1.51

2.24 and 1.84 at 5

30 and 60min post-injection respectively. The results suggested that it would be potentially useful as a brain perfusion imaging agent. 99m TcN-IBDTC also exhibited high myocardial uptake

but the washout from the heart was rapid and the heart/liver ratio was low thereby restricting the use of the complex as a myocardial perfusion imaging agent. The biodistribution results in mice suggested 99m Tc-IBDTC was mostly accumulated in liver

whereas the brain and heart uptake was very low. This study proves that the introduction of the [ 99m Tc≡N] 2+ core into the molecular structure of a radiopharmaceutical may obviously alter its biological behavior. This may be valuable for the design of new radiopharmaceuticals for clinical use.