Liver cancer PET diagnosis tracer agent and preparation method and application thereof

The invention belongs to the field of radioactive drugs and nuclear medicine, and relates to a liver cancer PET diagnosis tracer agent and a preparation method and application thereof. A 18F marked anti-CD105 alpaca heavy-chain single-domain antibody is shown as a structural formula: 18F-anti-CD105 alpaca heavy-chain single-domain antibody. Animal experiments show that the 18F marked anti-CD105 alpaca heavy-chain single-domain antibody has the advantages that on one hand, uptake values of tumors for the antibody and tumor imaging sensitivity are both high; on the other hand, uptake values of the liver for the antibody is quite low, and accordingly the antibody causes little toxic or side effect on the liver. Thus, the 18F marked anti-CD105 alpaca heavy-chain single-domain antibody can be used as the PET diagnosis tracer agent and the liver cancer PET diagnosis tracer agent in particular.