[en] Aim: To study the biological properties of a new myocardial perfusion imaging agent [^99mTc(CO)₃(MIBI)₃]⁺ in animal and compare with ^99mTc-MIBI. Materials and Methods: The preparation of the [^99mTc(CO)₃(MIBI)₃]⁺ complex was carried out. The first step, the organotechnetium aqua-ion ^99mTc[(CO)₃(OH₂)₃]⁺ was synthesized. Na₂CO₃, NaBH₄ and NaK-tartrate were added to a penicillin vial, a 3ml sample of a generator elute was heated for 30 min, after cooling to room temperature, a solution of PBS was added to neutralize the solution. The second step, then MIBI with other additives were added to the produced ^99mTc[(CO)₃(OH₂)₃]⁺ solution, and was heated to 100⁰C for 30 min. The labeling rate was over 90%. Dynamic imaging of normal anesthetized dogs was performed using TOSHIBA GCA-7200A didetector SPECT. A dose of 555 MBq of [^99mTc(MIBI)⁶]⁺ and the produced [^99mTc(CO)₃(MIBI)₃]⁺ were respectively injected via vein into dogs. The whole body imaging was carried out at fixed time intervals in order to obtain the in vivo biodistribution. Planar and tomographic imaging of myocardium was performed up to two hours, and intravenous blood samples were collected at different times to gain the clearance dynamics of the [^99mTc(CO)₃(MIBI)₃]⁺ complex in blood. Results: the clearance curve of [^99mTc(CO)₃(MIBI)₃]⁺ in blood occurs with the onetime intravenous injection, pharmacokinetics quadratic model, T(α)_1/2=1.33 ± 0.12min, T(β)_1/2=102.33 ± 25.58min, CL=401.33 ± 73.51ml/hr. The time-activity curves showed that the hepatic curve of [^99mTc(CO)₃(MIBI)₃]⁺ was lower than its myocardial curve, while the hepatic curve of [^99mTc(MIBI)₆]⁺ was obviously higher than that of myocardium at the same dog. The myocardial uptake (%ID) of [^99mTc(CO)₃(MIBI)₃]⁺ complex were higher than that of [^99mTc(MIBI)₆]⁺, and heart-to-lung and heart-to-liver activity ratios of [^99mTc(CO)₃(MIBI)₃]⁺ complex were significantly higher than that of [^99mTc(MIBI)₆]⁺. The planar and tomographic images can be obtained from 10 to 120 min postinjection of [^99mTc(CO)₃(MIBI)₃]⁺ without the negative influence of liver images, and radioactivity in liver was apparently lower than that of [^99mTc(MIBI)₆]⁺. Conclusion: The results of this study show that the [^99mTc(CO)₃(MIBI)₃]⁺ is better than ^99mTc-MIBI in myocardial imaging and warrant further investigation as a potential myocardial perfusion imaging agent