[¹⁸F]FDG PET/CT enables in vivo quantification of cerebral glucose metabolism, revealing functional abnormalities before morphological changes on CT or MRI. This review summarizes major clinical indications, methodological aspects, and key metabolic patterns. In cognitive impairment, [¹⁸F]FDG PET is a core biomarker within the amyloid/tau/neurodegeneration (A/T/N) framework, predicting conversion from mild cognitive impairment (MCI) to Alzheimer’s disease (AD) and differentiating AD, dementia with Lewy bodies (DLB), frontotemporal lobar degeneration (FTLD), vascular dementia, and atypical parkinsonian syndromes (APS). In movement disorders, it distinguishes Parkinson’s disease (PD) from APS – including multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS) – and supports prognosis in amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD). In epilepsy, interictal hypometabolism aids localization of the epileptogenic zone, especially in MRI- negative cases, while in neuro-oncology, [¹⁸F]FDG PET assists in primary central nervous system lymphoma (PCNSL), glioma grading, and recurrence assessment. The review also highlights roles in inflammatory and infectious diseases, such as autoimmune encephalitis, neurosarcoidosis, and post-coronavirus disease 2019 (COVID-19) sequelae. Standardized preparation, glucose control, and statistical comparison with normal databases remain essential for accurate interpretation.
