Objective:

Prostate specific membrane antigen (PSMA) is a well-established target for diagnosis and therapyof prostate cancer (PCa). We have synthesized an amino-functionalized PSMA inhibitor (Glu-Urea-A) and labeled technetium-99m via HYNIC. The in vivo target capacity of the new probe was evaluated in animal model and compared with

18

F-fluorodeoxyglucose (18F-F

DG) and

11

C-choline which were mostly used in clinic.

Methods:

The new probe was studied in severe combined immunodeficiency (SCID) mice bearing PC-3 and LNCaP tumor xenografts on small animal SPECT/CT. The comparative analysis of

18

F-FDG and

11

C-choline imagings was done in LNCaP tumor xenografts on small animal PET/CT. The tumor to muscle ratio wasobtained by the analysis software accompanying with small animal SPECT/CT and PET/CT respectively.

Results:

The imaging results showed that the metabolism of

99m

Tc-HYNIC-Glu-Urea-A was very fast. Kidney was the primary excretory organ and little radioactive uptake was found in intestines. There was no significant uptake in other organs. PC-3 tumor did not have any radioactive uptake. LNCaP tumor had very high radioactive uptake

and the tumor to muscle ratio was 20.4. The blocking experiment showed that the tumor uptake reduced significantly. The tumor to muscle ratio obtained from PET/CT imaging were only 2.1 and 2.6 for

18

F-FDG and

11

C-choline respectively

which were much lower than

99m

Tc-HYNIC-Glu-Urea-A.

Conclusion:

The probe

99m

Tc- HYNIC-Glu-Urea-A with fast metabolism and high tumor uptake was a promising molecular imaging probe targeting PSMA. It is superior to

18

F-FDG and

11

C-choline in prostate cancer imaging.