The diagnosis of neurocognitive disorders is challenging for clinicians. Accurate diagnosis is important because emerging therapeutic regimens vary depending on the cause of dementia. We review various Imaging biomarkers along with characteristic spatial patterns of brain metabolism through Digital FDG-PET in patients with suspected dementia.  

The workup of patients with cognitive impairment which includes mild neurocognitive disorder - MCI and major neurocognitive disorder -dementia (fig 1 and 2) involves anatomic imaging (computed tomography [CT] and magnetic resonance [MR] imaging) performed concurrently with biochemical and laboratory investigations to exclude dementia due to structural, vascular, metabolic, inflammatory, hormonal or toxic causes. However, once these secondary causes have been ruled out, anatomic imaging techniques are limited in their ability to  distinguish between various forms of dementia, since atrophy and ventricular enlargement are often late signs of disease.

Positron emission tomography with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) allows detection of neurodegenerative disorders earlier than is otherwise possible. Accurate interpretation of characteristic patterns of altered metabolism seen at FDG PET can markedly improve the clinical diagnosis for specific types of dementia such as FTD, Alzheimer disease, and DLB each of which has characteristic metabolic signatures.