Perfusion imaging

The term perfusion has varied connotations in different situations. The word perfusion comes from the Latin to pour or diffuse through or over. Myocardial perfusion depends on (a) coronary artery or vessel flow, and (b) myocardial or muscle flow. The factors which determine perfusion at rest and during stress in coronary vessels and within the myocardium are clearly related but not with a predictable linear relationship. In animals there is extensive literature concerning the regulation of coronary flow and perfusion obtained by many sophisticated methods. In contrast, the techniques that are applicable to humans are relatively crude. To date, the clinical data available suggests that the normal control of coronary flow in man and in dogs is fairly similar but that models of pathology in animals bear little relation to the compensatory changes found in the coronary circulation in man. Although the data available is limited and subject to many technical inaccuracies, this article is confined to the assessment of myocardial perfusion in clinical practice.