thallium scan

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thallium scan (thal-iŭm) n. a method of studying blood flow to the heart muscle (myocardium) and diagnosing myocardial ischaemia using an injection of the radioisotope thallium-201. Defects of perfusion, such as a recent infarct, emit little or no radioactivity and are seen as ‘cold spots’ when an image is formed using a gamma camera and computer. Exercise may be used to provoke ‘cold spots’ in the diagnosis of ischaemic heart disease.