mTcN(NOEt)2 is prepared through a two step ligand-exchange reaction by using SnCl2 as reduction agent and SDH (succinyl dihydrazide) as a donor of nitride nitrogen atom (N3-) at room temperature. The labelling procedure is more convenient for clinical use. The radiochemical purity (RCP) of the product is over 90% by TLC. The biodistribution results in mice indicate that 99mTcN(NOEt)2 has high myocardial uptake. For 5 min post injection the heart-to-blood

heart-to-liver and heart-to-lung ratios are 10.48

2.07 and 0.74

respectively. The uptake of brain is also good. For 5min post injection the brain uptake is 4.43%ID·g-1 and the brain-to-blood ratio is 1.12. Based on these results 99mTcN(NOEt)2 exhibits prommising properties for further studies.