The PET-enhancing radiotracer  PM-PBB 3 / APN-1 was developed by the Quantum Science and Technology Research Organization · National Institute of Radiological Sciences and recognizes aggregation and accumulation of tau protein causing neurodegenerative lesion diseases such as Alzheimer’s disease. It has orphan drug status in Japan. US Eli Lilly and Merck are said to do tau PET examination as well.https://www.jp.aprinoia.com

Aprinoia Japan news release, October 11, 2018