Ovulation and increased FDG uptake on PET: potential for a false-positive result.

F-18 FDG PET is increasingly used in the assessment of malignant disease. Normal physiologic activity of FDG can lead to false-positive results. The case of a patient with prior squamous cell carcinoma of the urethra and FDG uptake in the right ovary related to physiological activity during ovulation is presented. Suspicion for physiological ovarian uptake is necessary when assessing PET imaging of females of reproductive age when there is uptake of FDG in the ovarian region. It is therefore important to take a menstrual history and compare PET with cross-sectional imaging in an attempt to exclude physiological causes.