Objective        To prepare

99

Tc

m

-TP1326 and identify its physicochemical properties

and to study its tracer kinetics and distribution features in rabbits.       Method

s       Using stannous chloride as the reductive agent

GA(D)GG-Aba-RGD-4CK (TP1326) prepared by chemosynthesis was labeled with

99

Tc

m

. The labeling rate was determined by paper chromatography. Physicochemical properties of

99

Tc

m

-TP1326 were identified by stability test in vitro

serum albumin binding test and oil-water distribution test. The best compartment model and its pharmacokinetic parameters were obtained through determining rabbit blood radioactive concentrations at different time phase after intravenous injection of

99

Tc

m

-TP1326. SPECT imaging was applied to observe dynamic distribution of the peptide in the main organs of rabbits.       Results        The labeling rate and specific activity of

99

Tc

m

-TP1326 were (95.86±0.83)% and (38.62±0.32) TBq/mmol respectively. The radiochemical purity was (91.76±2.75)% after being conserved at room temperature for 4 h.

99

Tc

m

-TP1326 could not combine with serum albumin. The oil-water distribution coefficient was -(1.76±0.06). Dynamics of

99

Tc

m

-TP1326 in rabbits fitted for two-compartment model with a weight coefficient of 1/c

and the main parameters

t

1/2α

and t

1/2β

were (3.115±0.771) min and (76.978±22.460) min respectively. SPECT imaging showed that the blood pool radioactivity disappeared rapidly

and most radioactivities were eliminated through kidneys. There was no obvious nuclide aggregation in the intestines

stomach and neck region during the whole period. Low radioactive background was presented in the brain.       Conclusion      

99

Tc

m

-TP1326 can be easily labeled with a high labeling rate and stability

and it can be rapidly cleared mainly through kidney.

99

Tc

m

-TP1326 is a valuable molecular imaging agent targeting integrin α

v

β

3

receptor.