Brain imaging: applications in psychiatry.

Various brain imaging techniques have become available in the past decade. These include techniques to evaluate brain structure, such as computed tomography and magnetic resonance imaging, and techniques to assess functional activity, such as measurement of regional cerebral blood flow, single photon emission computed tomography, and positron emission tomography. These techniques can be used to map brain structure and function in normal human beings, and they have enlarged our knowledge of the pathophysiology of mental illnesses by demonstrating structural, metabolic, and neurochemical abnormalities in a wide range of mental disorders.