The basics of PET molecular imaging in neurodegenerative disorders with dementia and/or parkinsonism.

Positron emission tomography (PET) imaging biomarkers have become crucial in understanding and diagnosing neurodegenerative disorders. PET imaging allows for the in vivo quantification of molecular targets with high sensitivity, aiding in the study of disease pathophysiology and progression from preclinical stages. By visualising specific molecular pathologies, PET biomarkers enable a shift from symptom-based to biology-based definitions of neurodegenerative diseases, allowing for earlier and more accurate detection and diagnosis. This has significant implications for developing and testing new therapies aimed at modifying disease course. In this review, we will go through the standards of PET imaging in the evaluation of neurodegenerative disorders. Specifically, we will review PET molecular imaging of amyloid-β plaques, tau pathology, as well as the effect of neurodegeneration on neuronal activity in different disorders. Moreover, we will revise PET tracers targeting neurotransmitter systems such as the dopaminergic system which can detect early functional changes in movement disorders. Issues related to methods, image interpretation, normal findings and mimics will be an important part of this review. KEY POINTS: Question A review of PET molecular imaging tools for assisting the clinical diagnosis of patients presenting with cognitive impairment or parkinsonism and suspected neurodegenerative disease. Findings PET molecular imaging tools vary widely in their image acquisition protocols and image interpretation, allowing us to study different features of neurodegenerative diseases. Clinical relevance The majority of PET molecular imaging tools are currently in use in our clinical practice. Despite the differences between them, standardised visual reading methods and specific semi-quantitative parameters have been established, allowing for their use.