Time elapsed from the last PSA determination until PET was no more than 2 weeks in all patients. Patients will receive complementary workups including MRI (for patients suspicious for local or regional node recurrence), bone scan (for patients suspicious for distant bone metastasis), contrast CT (for patients suspicious for visceral organ metastasis or lung metastasis) subsequently after Ga68-PSMA ligand PET/CT scan no longer than two weeks.