Neuroimaging techniques are now common and almost routine as aids in the differential diagnosis of dementia. Structural imaging techniques, including computed tomography (CT) and magnetic resonance imaging (MRI), are used to rule out potentially reversible causes of the dementia syndrome, such as normal-pressure hydrocephalus and brain tumors. More recently and still very much experimental, imaging has been used to identify differences between patients with a particular cause of dementia who have particular behavioral and psychological symptoms of dementia (BPSD), and those without such symptoms. Such comparisons help confirm an organic basis for the BPSD and help elucidate the neural mechanisms that underlie BPSD.