PET is a noninvasive imaging technique that allows to measure specific physiological and pathophysiological processes within the human brain in vivo. Its high sensitivity and specificity is considered as a major advantage over other medical imaging modalities, allowing e.g. the assessment of cerebral metabolism / perfusion, of specific neurotransmitter/receptor systems, and of abnormal protein depositions in the brain.

A common clinical use of PET is to measure the cerebral rate of glucose consumption using the radiolabeled glucose analogue 18F-fluorodeoxyglucose (FDG PET). FDG uptake in the brain reflects neuronal function and neurodegenerative diseases are characterized by prototypical patterns of metabolic abnormalities indicating regional neuronal dysfunction.

FDG PET thus plays an important role in the early diagnosis / differential diagnosis of various neurodegenerative disease conditions. Other applications of PET include measurements of cerebral blood flow and oxygen consumption and tracking neurotransmitter / receptor systems, which typically show abnormalities in neurodegenerative diseases like e.g. Parkinson’s disease. More recently, it has become possible to measure the cerebral distribution of extracellular amyloid (amyloid PET) and intracellular tau (tau PET) proteins that characterize some neurodegenerative diseases. Therefore, PET can be understood as a form of ‘neuropathological imaging’ in vivo.

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