Perspectives on development of high temporal resolution PET detectors were discussed at a workshop held in Valencia, Spain in June 2022. In the workshop, researchers have discussed how we will develop the next generation PET systems towards 100 ps time-of-flight (TOF) PET. There are several challenges to make the 100 ps TOF-PET system practical although some research has achieved sub-100 ps coincidence time resolution at a laboratory level. The scope of the conference widely spans clinical motivation, system consideration, scintillator, photodetector, electronics, artificial intelligence, and image reconstruction. By putting them together, researchers believe that 100 ps TOF-PET system can be realized in near future. In this paper, the author will introduce several topics discussed in the workshop. In addition, the author share experience of the international workshop during the COVID-19 pandemic.