[Radioisotopes in cardiology. Introduction]

During the last fifteen years scientists in France and in other countries have developed several isotopic research techniques to the stage of current cardiological investigations. The most important advances have come in the last few years with the introduction of new tracer substances and computer-assisted imaging systems. Isotope techniques occupy an intermediary but quite separate position between the so-called "invasive" contrast radiological methods and the essentially "non-invasive" ultrasound investigations. The physical and biological basis of nuclear cardiology explains the complexity of these new methods, but also the quality of information which may be obtained. The proposed clinical usage necessitates a choice modulated by the properties of the radiopharmaceutical substances, the technical possibilities of the imaging system and the capacity of the associated computers. Several options are available from modern radio cardiographic probes to heavy tomographical systems with positron emitters, the choice depending on whether the study is to be limited to an assessment of global ventricular function using radioactivity/time curves, or whether detailed analysis of regional myocardial function by tomodensitometry is required. A satisfactory compromise may be obtained with a computer-assisted standard gamma-camera, equiped with a collimator for gamma tomodensitometry, in addition to the conventional scan projections. The price of this equipment is about one half that required for an X-radiological installation but the tt in all conditions with no risk apart from that of the "multiplication" of diagnostic procedures.