Functional Neuroimaging in Clinical Neurology: A Comprehensive Review of Commonly Used Modalities.

Functional neuroimaging has revolutionized our understanding of brain physiology and pathophysiology, providing dynamic insights into neural activity that complement structural imaging. This review examines the principal functional neuroimaging modalities used in routine clinical practice, positron emission tomography (PET), single-photon emission computed tomography, magnetic resonance imaging, and their clinical applications in neurology. We present an evidence-based approach to modality selection and interpretation, emphasizing the integration of multimodal imaging data to enhance diagnostic accuracy. Recent advances in molecular imaging have transformed the evaluation of neurodegenerative diseases, moving the field from observing the downstream consequences of disease to visualizing the primary molecular pathologies in vivo. The development of specific PET ligands for amyloid-β plaques, tau neurofibrillary tangles, neurotransmitter system components, and markers of synaptic density and neuroinflammation represents a paradigm shift toward a biological definition of these disorders. This review provides practical algorithms for clinical decision-making, critically evaluates the strengths and limitations of each technique, and highlights emerging applications that promise to further advance neurological diagnosis and management toward an era of precision medicine.