A 53-year-old man with recent diagnosis of urinary bladder carcinoma was referred to our PET/CT unit. There was no sign and symptom other than hematuria. Urinary ultrasound showed a mass lesion at the right wall of the urinary bladder. FDG PET/CT was performed for initial staging. One-hour whole-body PET/CT images were normal, whereas delayed pelvic images with "diluted and filled bladder" demonstrated that intense hypermetabolic lesion at the right lateral wall of the urinary bladder.