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Background
Cognitive impairment may pose as a diagnostic challenge particularly when there are overlapping clinical features and unremarkable structural imaging. Molecular imaging techniques, using various radiotracers may prove to be of immense help in such scenarios. The ability to image in-vivo, has helped us better understand pathogenesis, and hence, help direct research towards attempting to delay or prevent their occurrence. In this educational exhibit, we try to briefly review the role of nuclear medicine imaging in cognitive impairment.

Educational Goals / Teaching Points
The goals of this exhibit are to review the neuropathology and the key clinical features of various cognitive disorders, and radiotracers used for imaging the same; appropriate indications for their use; and the advantages and limitations of each; patient preparation, protocols and techniques followed for acquisition of scans; the classic metabolic signatures seen on functional imaging via a case-based approach; and briefly highlight the ongoing research in nuclear medicine imaging of cognitive disorders.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The key neuropathology to be reviewed includes types of abnormal protein deposition and Braak’s staging. The radiopharmaceuticals that will be discussed are 18F-fluorodeoxyglucose(FDG), amyloid tracers, and tau ligands. Clinical and functional imaging features of the following cognitive disorders will be discussed in detail. Mild Cognitive Impairment (MCI), Alzheimer’s Disease (AD) [including the typical and atypical variants], Vascular Dementia (VD), Dementia with Lewy Bodies (DLB) and Fronto-temporal Dementia (FTD).

Conclusion
In conclusion, we will provide a simplified algorithmic approach that will come in handy while interpreting nuclear medicine scans for the etiologic diagnosis of cognitive disorders.