Pediatric FDG PET/CT: Physiologic Uptake, Normal Variants, and Benign Conditions

Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) is increasingly being used in the evaluation of pediatric oncology patients. However, the normal distribution of (18)F FDG uptake in children is unique and may differ from that in adults. A number of physiologic variants are commonly encountered, including normal physiologic uptake in the head and neck, heart, breast, thymus, liver, spleen, gastrointestinal tract, genital system, urinary collecting system, bone marrow, muscles, and brown adipose tissue. Benign lesions with increased (18)F FDG uptake are also frequently seen and can be misinterpreted as malignancies. In addition, the use of combined PET/computed tomographic (CT) scanners is associated with pitfalls and artifacts such as attenuation correction and misregistration. Proper interpretation of pediatric (18)F FDG PET/CT studies requires knowledge of the normal distribution of (18)F FDG uptake in children, as well as of the aforementioned physiologic variants, benign lesions, and PET/CT-related artifacts. Knowing these potential causes of misinterpretation can increase accuracy in PET image interpretation, decrease the number of unnecessary follow-up studies or procedures, and improve patient treatment.