A 79-year-old man with prostate cancer was treated with prostatectomy. He presented with a rising prostate specific antigen (PSA) level of 6.00ng/mL. Gallium-68-prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) showed avid PSMA uptake in the posterior wall of the urinary bladder on the early stage (60s post injection; 5min post injection; 10min post injection). However, this lesion was difficult to distinguish because of adjacent physiological urine activity on routine imaging, delayed PET/CT and PET/magnetic resonance (MR) imaging. Our case indicates early dynamic scan is conducive to increasing the rate of detected lesions, especially for the existence of adjacent physiological urine activity disturbance lesions.