The purpose of this artical is to study the preparation and biodistribution in animal of dopamine transporter imaging agent

125

I- β-CIT. β-CIT was

125

I radioiodinated with odogen method

the dynamic distribution of

125

I-β-CIT in brain and critical organs were studied with SD rat （atuoradiography） and NIH mice respectively. The radiolabelling yield of

125

I-β-CIT was 84%

the radiochemical purity was better than 98%. Blood clearance could be explained by two-compartment model with a duration of 12h

(α = 3.87

T

1/2α

=0.179

β =0.162

T

1/2β

=4.276) and three-compartment model in 24h

(Pi= 5.28

T

1/2Pi

= 0.131

α = 0.403

T

1/2α

. = 1.719

β= 0.040

T

1/2β

= 17.298). The maxim uptake rate of brain （9.1% ± 1.0%） was reaches at lh

while at 24h

the target/noise ratio was higher. Critical organs liver

lung

spleen and kidney had high uptake rate [（9.881 1.43）- （16.29± 1.72）]

except liver

other organs showed quick clearance (T

1/2

<

4h). Thyroid had a low uptake. Autoradiography of the brain showed that striatum uptake was good

striatum /cerebral cortex radioactivity ratio achieved maximum at 20h. The results show that

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-β-CIT has a high striatum uptake and good stability in vivo

can provide good SPECT forages

the best acquisition time of SPECT may be about 20h after i.v..