The Use and Applications of Single-Photon Emission Computerised Tomography in Dementia

The introduction of single-photon emission computerised tomography (SPECT) has markedly enhanced the study of brain function. The development of SPECT was the culmination of a series of investigations of cerebral blood flow (CBF) pioneered by Kety and Schmidt in the late 1940s combined with the introduction of transmission computerised tomography (CT) in the early 1960s, in which three-dimensional images are derived from two-dimensional data. Positron-emission tomography (PET), in addition to providing information on cerebral blood flow, also allows the evaluation of brain metabolism and neurotransmitter receptor function. However, the technology required for PET is expensive and sophisticated, with little prospect for general clinical application. Fortunately, SPECT is relatively cheap and is widely available for clinical use. We aim to review the principles and basic techniques of SPECT, its present utility and application to clinical practice, and its future potential in the investigation of brain function.