Myocardial infarct imaging using 99m technetium pyrophosphate and 99mtechnetium methylene diphosphonate: a clinical evaluation.

THE use of radionuclides in elucidating ischaemic heart disease is a recent development. Since Bonte et al. (1974) first described the concentration of 99mTechnetium labelled phosphates in acutely damaged myocardium numerous radiopharmaceuticals, techniques, experience and data have accumulated in the non-invasive imaging methods for the direct visualisation of acute myocardial infarction. The radioisotopes may be used dynamically to provide information about the size of cardiac chambers, the ventricular ejection fraction, ventricular wall motion or regional perfusion of the myocardium. The radioisotope is injected rapidly as a bolus into a peripheral vein and its passage through the heart is recorded with a scintillation gamma camera interfaced with a data processor or computer system. Alternatively isotopes may be used for static imaging after equilibration and intracellular radioactive uptake occurs, displaying areas of normal, ischaemic or infarcted myocardium. Both techniques avoids cardiac catheterisation and are non-invasive, cheap, sensitive, safe, reproducible and repeatable. If a mobile gamma. camera is available it can be done at the bedside and becomes extremely useful in the intensive care. where the physician has to continuously monitor for changing cardiac physiology in .ill cardiac patients. These techniques provide for the early diagnosis, sizing of the infarcted area, incrimination of the coronary arteries affected follow-up studies, and monitoring effect of therapy.