Use of Propranolol to Reduce FDG Uptake in Brown Adipose Tissue in Pediatric Cancer Patients PET Scans

This is a single-arm, open-label study to assess the safety and effectiveness of a single dose of oral propranolol in reducing18F-fluorodeoxyglucose (FDG) uptake in brown adipose tissue (BAT) in pediatric oncology patients. This study is designed to better understand if taking a single dose of an oral medication called propranolol can reduce the chance of brown fat showing up on a PET scan, and therefore make the scan more accurate and easy to interpret. All humans have some degree of normal brown fat (called brown adipose tissue), and this normal tissue can sometimes light up on a PET scan. That creates problems because it may be wrongly interpreted by the radiologist as tumor, or it may hide true areas of tumor underneath it. Participants will not be randomized and will receive a single dose of oral propranolol approximately 60 minutes prior to the injection of the FDG tracer. The dose of propranolol will be 20 mg for all participants.