Brain scans

• CT or CAT (computerized axial tomography) involves scanning from different angles with an X-ray tube and detector system, and reconstruction of cross-sectional or coronal pictures to provide views of both the brain and the ventricular system.

• MRI or NMR (nuclear magnetic resonance) works by recording the response to radio waves applied to the body within a magnetic field. Clear pictures of both white and grey matter may be obtained from any desired angle. MRI is superior to CT for some purposes, but less widely available.

• PET (positron emission tomography) works by detecting local concentrations of radioisotopes, and provides information about function, such as glucose or oxygen consumption and the activity of various neurotransmitters.

• SPECT (single photon emission computerized tomography) utilizes nuclear radiotracers to localize different receptors.

PET and SPECT are available in only a few centres in the UK, and are likely to remain research tools for the foreseeable future.

Further reading

Sims, A. C. P. (2002). Symptoms in the Mind: An Introduction to Descriptive Psychopathology (3rd edn). London: Bailliere Tindall.

Part II Clinical syndromes

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