As a new dual receptor (SSTR2 and FAP) targeting PET radiotracer, 68Ga-FAPI-LM3 is promising as an excellent imaging agent applicable to SSTR2 positive diseases. In this research, we investigate the safety, biodistribution and radiation dosimetry of 68Ga-FAPI-LM3 in healthy volunteers. Moreover, we evaluate the potential usefulness of 68Ga-FAPI-LM3 positron emission tomography/computed tomography (PET/CT) for the diagnosis of lesions in SSTR2 positive diseases, and compared with 18F-FDG PET/CT.

As a new dual receptor (SSTR2 and FAP) targeting PET radiotracer, 68Ga-FAPI-LM3 is promising as an excellent imaging agent applicable to SSTR2 positive diseases In this research, we investigate the safety, biodistribution and radiation dosimetry of 68Ga-FAPI-LM3 in healthy volunteers. Moreover, subjects with SSTR2 positive diseases underwent contemporaneous 68Ga-FAPI-LM3 and 18F-FDG PET/CT for diseases assessment. Lesions uptakes were quantified by the maximum standard uptake value (SUVmax). The numbers of positive lesions of 18F-FDG and 68Ga-FAPI-LM3 PET/CT were recorded by visual interpretation. The diagnostic accuracy of 68Ga-FAPI-LM3 were calculated and compared to 18F-FDG PET/CT.

Inclusion Criteria:

• (i) adult patients (aged 18 years or order);
• (ii) patients with suspected or newly diagnosed or previously malignant disease, with either FAP or SSTR2 positive expression (supporting evidence may include MRI, CT, and pathology report etc);
• (iii) patients who had scheduled both 18F-FDG and 68Ga-FAPI-LM3 PET/CT scans;
• (iv) patients who were able to provide informed consent (signed by participant, parent or legal representative) and assent according to the guidelines of the Clinical Research Ethics Committee.

Exclusion Criteria:

• (i) patients with non-malignant disease;
• (ii) patients with pregnancy;
• (iii) the inability or unwillingness of the research participant, parent or legal representative to provide written informed consent.