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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.

50 patients were investigated by both left ventricular cine-angiography, and "balanced" gamma-cine-cardiography in the frontal and LAO positions. Measurements of the ejection fraction and the mean and maximal speeds of contraction were made by the two techniques. The correlation was good (r = 0.89 for the ejection fraction). A morphological analysis of the dynamic findings in the two methods in the 12 cases with discordered left ventricular kinetics showed that once again the results were very similar. A numerical presentation of the data from the radioisotope studies was made either as a group of sequential ventricular contours successively from diastole to systole, or to give a functional picture which would provide the value for one kinetic paramter at any one time (for example, the regional equivalent of the ejection fraction). To overcome the problems of superimposition in the RAO position in the "balanced" technique, the recordings of the first radioisotope study in RAO were combined with a study of balance in 50 other patients, and the correlation was excellent. These two isotope techniques, which can be carried out in the same examination and which may be repeated without risk, perfectly complement each other, and very few of the results were incapable of interpretation.

An analytical study of 320 case reports of patients with one or more thyroid nodules, 246 of whom had been operated upon, revealed the presence of 32 cancers, 15 toxic nodules, and 195 inactive benign uni- or multilobular goitres. Complementary examinations (scintigraphy with technetium, thermography, ultrasonography) cannot definitely establish the benign nature of a nodule. As long as cytological examination after needle biopsy, which requires the services of a highly specialised cytologist, will not become a routine procedure, histological examination is essential for correct diagnosis. Any nodule should be excised, therefore, and the thyroid explored completely.

The imaging of the cardiac cavities with appropriate tracer materials (99 m Technetium or 113 m Indium), the recording of intracardiac dilution curves by radionuclide angiography and dynamic studies by gamma cinecardiography give global and regional parameters of left ventricular function which are reliable and reproducible: an index of cardiac output, intracardiac circulation times and ventricular volumes. The assessment of left ventricular contraction and global and regional ejection fractions is facilitated by coupling the gamma camera and the electrocardiogramme and computer analysis of the results. "First passage" recordings may be used to differentiate the right from the left heart chambers. "Equilibrium" studies give detailed information at rest, under stress (or leg-raising) and under pacing and/or trinitrin. Average and maximal rates of contraction derived from the ejection fraction and left ventricular contraction times are indices comparable to the rate of fibre shortening. The calculation or regional parameters point by point such as the ejection fraction, contraction time and ejection volume gives a more accurate and sensitive estimation of left ventricular function than the global left ventricular indices. They are many practical applications in cardiology especially in coronary artery disease: monitoring the changes in the acute phase of myocardial infarction, the selection of patients for aorto-coronary bypass surgery and their pre- and post-operative controls. These non-invasive, easy and reliable cardiac studies justify the development of laboratories of nuclear cardiology within departments of cardiac physiological investigation.

The amount of diastolic blood flow in the carotid and vertebral axes determines the tolerance capacity of the cerebral circulation to physiological variations. In the elderly subject this "circulatory reserve" is modified by increases in cerebral circulation resistance, but also by various common cardiac or blood pressure disorders. Furthermore, direct visualization of the atheromatous plaques and calcifications in the vessel walls by ultrasonography can reveal lesions that have no clinical expression.

28 patients with primary congestive cardiomyopathy in heart failure identified by cineangiographic criteria (end-diastolic volume greater than 120 ml/m2; parietal thickness less than 11 mm; normal coronary angiography), underwent 131-Cesium and 201-Thallium myocardial scintigraphy in antero-posterior and LAO projections, and 17 also underwent angiocardiography with 99 Technetium labelled albumin. This condition usually gives an appearance of an enlarged heart with diffuse or localised (antero lateral wall) hypofixation, dilatation of the left ventricular, left atrial and right ventricular cavities and a very low ejection fraction with diffusely hypokinetic wall motion. Radio-Isotopic methods may help discriminate primary and ischaemic cardiomyopathy but are not diagnostic. A low ejection fraction and marked diffuse hypofixation are poor prognostic indices. Radio-Isotopic methods are valuable in the classification of primary cardiomyopathy.

The radionuclide angiography, of gamma-angio-encephalography (gamma-A.E.G.), a non invasive method, is able to bring specific information for the diagnosis of intracerbral hematoma (I.C.H.). In 25 out of 32 verified cases of I.C.H. the rapid sequential imaging shows from the arterocapillary time a deeply seated avascular area, which is a quite different aspect from the defect observed in ischemic A.C.V., or malignant tumors. The transit curves confirm the regional of circulating blood pool.

Simultaneously to the development of new techniques such as the computerized axial tomography, the gamma-angioencephalography is progressing in the field of cerebral investigation in its original way, keeping on non invasing character. In view to analyze this evolution we shall examine first its technical possibilities, then the extractible data of the various techniques. Finally we will consider in which way we must bring most of our effort for the best utilization of the gamma-angioencephalography in the routine work, on one hand, and for progressing in the knowledge of the physiopathology of some lesions, specially vascular accidents, on the other hand. Technical modalities are multiple. Besides the standard technique (pertechnetate angiography with rapid sequential views, regional transit curves, early and late static views) it is possible to replace or to repete the injection: --changing the patient's position, --using another radiopharmaceutical labelled with technetium -or another isotope, or two tracers for two compartments; --carrying out a pharmacodynamic or CO2 test, --using radioxenon, and secondly a pure vascular tracer, to measure relative regional blood pool and relative regional blood flow. a) morphological ones (vascular tracks, regional blood pool, radioactive areas: number, form, homogeneity, outline), b) dynamic and quantitative ones (transit times, blood flow, extravascular diffusion, changes of these parameters when changing the radiopharmaceutic, or when using a test). Progresses can take place in three ways, very closely related to each other: a) In the methodology, to precise --relative merit of the different radiocompounds according to the various cerebral lesions, --methods for examination according to the clinical problems, --computing and date processing techniques. b) In the indications, to choose the best, the simplest, though the surest method for the daily clinical problems, and the best one to assemble special information escaping to the morphological radiological techniques. This choice needs frequent and close discussions between clinicians and nuclear specialists. c) In the signification of the data, to interprate correctly: --preferential uptakes in lesions or in compartments, --changes in the relative volumes of vascular bed and extravascular space in lesions, --vascular reactivity to an hemodynamic test, --accumulation or clearance of a diffusible tracer such as xenon. It is not always easy to reach a non equivocal interpretation of a whole group of data. It can be better to give a descriptive analysis which brings together elements for the diagnosis and physiopathological observations helpful for a therapeutic action and to follow up the disease at short and long term.

Red blood cells labelled with radioactive Technetium were injected intravenously, and the passage of the tracer through the cardio-pulmonary system recorded using a scintillation camera coupled with a numerical dosimeter. The results are presented as serial analoque pictures taken at the rate of two per second, as numerical tracings which are later processed, and as flow charts from predetermined areas of interest: the chambers of the heart, the lung parenchyma, and the aorta. This study is concerned with 58 patients with a left-to-right shunt, and about 40 normal examinations were used as a baseline for comparison. In cases of left-to-right shunt, the finding on the tracings is of abnormally prolonged activity in the lungs after a normal passage through the right side. The intensity-duration curves highlight this finding, and show an early recirculation peak in the right side of the heart and a slowing of pulmonary emptying, which can be evaluated numerically from the ratio C2/C1. A correlation has been found between this value and the ratio of pulmonary to systemic flow as calculated by oximetry. The correlation is even closer if a comparison is made between the curves of pulmonary radioactivity and the dye dilution curves. In certain cases, the shunt can be localised to the atrial or ventricular level. There are many indications for this safe investigation: --the diagnosis and monitoring of the flow through a left-to-right shunt in a child; --confirmation of the closure of septal defects after surgery; --clarification of an infudibulo-pulmonary syndrome.

Two randomized series of 60 cases of myocardial infarction or menace syndrome have been treated at the acute stage, one by Heparin alone, the other by the combination Urokinase-Heparin. The average dosage was 300 mg Heparin in the first series, of 2,700,000 CTA units of Urokinase combined with 240 mg of Heparin in the second series. After the first 24 hours, equal heparinization was performed in both series up to the third week. Significantly different results were obtained in the two series. They favour Urokinase and concern: -- the disappearance time of pain, -- the course of the arrhythmias and of cardiac failure, -- the regression or limitation of the necrosis q waves and the lesion areas on the electrocardiogram. Finally the 30th-day overall mortality was 13% in the Heparin series and 3% in the myocardial infarction on the way of constitution, or which have done so for less than 24 hours.

A total of 122 cases of various neurological diagnoses (among which 72 cerebral infarcts, 7 intracerebral hematomas and 38 intracranial tumors) had two separate brain scans, performed within 48 hours of each other after the administration of pertechnetate and technetium stannous pyrophosphate. The comparison of the resulting seans indicates that, in addition of an osseous accumulation, the pyrophosphate localizes greatly in ischemic cerebral lesions, especially those observed during the second week of evolution. It seems that the uptake of pyrophosphate reflects the area of anaerobic changes whereas the accumulation of pertechnetate depends on the disruption of the blood brain barrier. The scintigraphic diagnostic of cerebral infarctions is greatly improved.

The constant progress in surgical techniques during the last few years have prepared the way for important developments in the field of noninvasive cardiac exploration. Their non-traumatic character, appreciable in diagnostic and preoperative examinations, become indipensable whenever there is a need to repeat the examination in order to evaluate the effects of a treatment or to monitor progress both in the short and long term. In order that such methods be adopted in cardiac surgery it is important that not only must they be without risk but also that the results obtained be clearly presented, if possible in the form of images, and allow a quantitative interpretation. It is necessary also that the results can be justified both by clinical experience and also by comparison with other examinations. No procedure, not even radiologic, can at the same time explore the myocardium and its perfusion, the central circulation and the cardiac haemodynamics. By reason of their respective principles, radioisotopic methods and ultrasounds tackle cardiac problems in different ways and facilitate, by appropriate choice of methods, the selection of one diagnostic response from among several. This paper contains first of all, a resume of the principal nuclear and ultrasonic techniques used together with their basic principles. Next we try to show how these non-invasive techniques, most with dynamic imaging, can assist cardiac surgery. For this, we successively look at the different pathologies, working from the exterior (pericardium) towards the interior (intracardiac structures and central circulation) and covering the different aspects of the myocardial pathology. In each case the mutual contributions of physical techniques is specified as well as the preference for either isotopic or ultrasonic methods.

Cardiac kinetics can be visualized in two ways after i.v. injection of radiopharmaceutics for labeling either the myocardium or the cardiac chambers. The simpler way is the acquisition of the data in analog mode, using a multiimaging device. Thanks to a short time constant for the image advance, the cardiac cycle is divided into 16 frames, the first being triggered by the R wave of the ECG. The data of a large number of synchronized cycles are integrated on a film. This permits an almost continuous way to follow the kinetics of the studied compartments along the cycle. Several views can be registered successively. This procedure yields separately immediate information on the morphology and dynamics of the myocardium, and chambers. To evaluate quantitatively various parameters of left ventricular function a data processor is connected to the gamma camera. Examples of the two types of data are shown and demonstrate that both are useful for appreciating the value of kinetics though they are not yet accurate enough to replace in every case contrast radiologic techniques. Nevertheless, the indications for these procedures are continuously growing, due to technical progresses and the noninvasive nature of the investigation.