HYPERMETABOLISM ON PEDIATRIC POSITRON EMISSION TOMOGRAPHY SCANS OF BRAIN GLUCOSE METABOLISM: What does it signify?

Abstract

When interpreting clinical 2-deoxy-2[¹⁸F]fluoro-D-glucose positron emission tomography (FDG-PET) scans of the brain (excluding tumors), the typical abnormality is hypometabolism of various brain regions. Focal areas of hypermetabolism are noted occasionally and the usual interpretation is that the hypermetabolic region represents a seizure focus. In this review, we discuss and illustrate the multiple causes of hypermetabolism that should not be interpreted as seizure activity could potentially lead to an incorrect interpretation of FDG-PET studies. Various causes or conditions where focal hypermetabolism can be encountered on FDG-PET studies include interictal hypermetabolism, Sturge-Weber syndrome, changes associated with brain plasticity following injury, Rett syndrome, hypoxic-ischemic brain injury, various inborn errors of metabolism, and autoimmune encephalitis. The radiologist or nuclear medicine physician interpreting clinical FDG-PET studies should be aware of these circumstances to provide accurate assessment of the study.