In terms of the diagnostic technology of brain neurodegenerative diseases, the injection of positron tracers into the human body, so that it can combine with the corresponding protein, and show its distribution through PET imaging is a mature technology in the industry. At present, several research groups around the world are working on the development and clinical efficacy evaluation of their respective tau imaging agent compounds.This clinical research project intends to display the abnormal changes of tau protein in living brain through [18F]PM-PBB3 PET imaging, which is a second-generation tracer further optimized on the basis of [11C]PBB3, and has the advantages of closer binding to tau protein entanglement and less non-specific binding than similar imaging agents. Better image quality and a wider range of clinical applications.

Inclusion Criteria:

• Between 45 and 90 years old; No gender limitation. Brain MRI supported the diagnosis of neurodegeneration, and there was no evidence of other neurological diseases.

Informed consent signed in person by the subject or his legal guardian or caregiver.

Exclusion Criteria:

• Have other serious neurological disorders, or gastrointestinal, cardiovascular, liver, kidney, blood system, tumor, endocrine, respiratory, immune deficiency, and other serious diseases.

Received an experimental drug or device within 1 month (whose efficacy or safety is unclear).

patients who were unwilling to undergo PET/CT scans. pregnancy.