Normal physiological variants and benign conditions in pelvic oncologic fluorodeoxyglucose positron emission tomography/magnetic resonance imaging

Fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) is an advanced hybrid imaging modality that holds substantial promise in oncologic imaging. FDG PET, a well-established molecular imaging technique, enables assessment of tumor glucose metabolism and is widely utilized for diagnosing and monitoring a range of malignancies; MRI offers superior soft tissue contrast, facilitating precise anatomical localization of PET findings. This pictorial essay presents a series of physiological FDG uptake variants observed in the uterus, fallopian tubes, ovaries, colon, internal anal sphincter, pelvic musculature, and bone marrow. Additionally, it highlights benign conditions such as uterine tumors, vaginal condyloma acuminatum, and infected Bartholin cysts that may exhibit FDG uptake and potentially mimic malignancy. The essay also illustrates FDG-avid post-treatment changes and various infectious and inflammatory lesions such as osteitis pubis, perianal fistulas, and pelvic abscesses that may complicate oncologic interpretation.