Normal Variants and Pitfalls of 18F_FDG PET/CT in Pediatric Oncology

Although pediatric cancer is relatively rare compared with adult cancer, it is the second most common cause of death, after injury in children and adolescents. lymphoma, Leukemia, and brain cancer, account for more than half of pediatric cancers, followed by neuroblastoma, soft-tissue sarcomas, Wilms tumors, and bone tumors .

18Fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) plays an important role, staging, restaging, response to treatment in childhood malignancies. PET-only examinations have been replaced by hybrid systems in the recent decades, where PET and CT are used together in oncology. In this imaging system, PET and CT are used together for functional data and morphological information, respectively. (2) Although 18F-FDG PET/CT is now well established as an accurate method for the staging and restaging of various cancers, it is also well recognized that many false-positive results can occur .

The normal distribution of FDG uptake in children differs from adults. Also, even though FDG is used widely in oncology, it is not tumor specific. Uptake of FDG may be seen in numerous benign conditions, including inflammation, infection, and trauma. Proper interpretation of pediatric FDG PET/CT studies requires knowledge of the normal distribution of FDG uptake in children, and an insight into the physiologic variants, benign lesions, and PET/CT related artifacts.

By understanding the potential causes of misinterpretation, we can increase the accuracy of interpretation, decrease the number of unnecessary follow-up studies and improve treatment outcome.

Inclusion criteria

• All Pediatric Cancer patients referred to nuclear medicine unit to do 18F-FDG PET/CT study.

All patients > or = 18 years.

Exclusion criteria

• Severely ill patients. Patients with glucose level < 200 mg/dl.