Repetition of FDG PET study in the same day after appropriate patient preparation revealed two new cancer localizations: a case report.

A positron emission tomography scan with fluorodeoxyglucose can be affected by several factors. Skeletal muscle activation and physiological presence of radioactivity in urine frequently cause difficulties in images interpretation. We report a case of a patient with a non-operable left lung cancer, who was scheduled for FDG PET examination for radiotherapy planning purposes. In the first scan performed in the morning both elevated muscular and urinary uptake were present. For this reason another examination was performed on the same day. A new dose of radiopharmaceutical was given five hours after the first FDG injection and the patient was instructed to drink a large quantity of water in the meantime. The second PET scan clearly revealed two new lesions not visible at the time of the first examination: a synchronous bladder cancer, previously not known, and a mediastinal metastasis of the primary lung cancer. This case emphasizes the importance of correct patient preparation and shows the possibility to repeat PET examination on the same day.