Clinical neuroimaging in psychiatry.

The practical aspects of contemporary neuroimaging techniques relevant to clinical psychiatry are reviewed. In particular, the structural imaging modalities of computed axial tomography (CT) and magnetic resonance imaging (MRI) are described and compared. Likewise, functional neuroimaging modalities including the nuclear imaging techniques of positron emission tomography (PET) and single photon emission computed tomography (SPECT), as well as the newer magnetic resonance techniques of functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS), are reviewed. Although structural imaging techniques are most useful for ruling out medical etiologies of mental status disturbances, functional neuroimaging techniques currently have an adjunctive role in the evaluation of dementia and seizure disorders and show promise for the evaluation of primary psychiatric disorders in the future. Specific guidelines are suggested regarding the use of these neuroimaging studies.