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Biomedical subjects

R Itti

Publications and source records attributed to R Itti.

At least 55 records · Page 3Linked to original sources
PubMed1984

Meta-iodobenzylguanidine adrenal medulla localization: autoradiographic and pharmacologic studies.

In order to investigate the mechanism of uptake of meta-iodobenzylguanidine (mIBG) by the adrenal glands, autoradiographic and pharmacologic studies were performed in mice and dogs receiving radioiodinated mIBG. In mice, on macroautoradiography of whole body sections 48 h after 125I-mIBG, most of the radioactivity was focused in the adrenal glands. On microautoradiography, silver grains were exclusively located in the adrenal medulla. Tissue counting after phenoxybenzamine, cocaine, and desipramine treatment resulted in 45%, 35%, and 0% inhibition of mIBG uptake, respectively. Tissue counting and scintigraphic studies demonstrated a more than 50% mIBG release from the adrenal glands after reserpine. These data indicate the high affinity of mIBG for adrenal medulla and suggest that the mIBG and catecholamine uptake mechanisms are only partially the same.

3-Iodobenzylguanidine↗
PubMed1984

[Radioisotopic tomography in the study of cardiac function].

Dynamic tomographic images of the heart may be obtained by computerised treatment of a number of projections and planes recorded by a gamma camera rotating around a patient whose blood is labelled with radioactive technetium. This new technique of assessing cardiac function was tested in a group of 40 coronary patients and the results compared with standard contrast angiography. The following parameters were compared : LV volume, global and regional ejection fractions. The zones of interest were easily defined on the tomographic images and correction for background noise was negligible. Two different methods have been developed to measure volume. The first consists in counting the matrix units in three dimensions on serial planes through a given cavity. The second is based on the reconstruction of thick slices integrating all the ventricular radioactivity, the counting of which is calibrated with reference to an orthogonal plane. The correlations with angiography were excellent with both methods (R = 0,85 and 0,87 respectively). An equally good correlation was observed for ejection fraction (r = 0,85). A segmental model acceptable for both gamma line angiography, gamma tomography and contrast angiography comprises 6 segments : septal, apical, antero-lateral, postero-lateral, posterior, and inferior. The sensitivity and specificity of both isotopic methods of detection of major wall abnormalities (akinesia and dyskinesia) were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Radioisotopic quantification of isolated mitral insufficiency].

A group of 23 consecutive patients with isolated mitral regurgitation confirmed by angiography, 8 of whom had normal and 15 abnormal coronary arteriographies, were compared with a control group of 27 subjects without valvular heart disease (normal coronary arteriography in 7 cases, abnormal coronary arteriography in 20 cases). After injection of technetium 99m labelled albumin, gamma-angiocardiography was performed in the left anterior oblique plane at equilibrium with electrocardiographic synchronisation. Fourier's analysis of the images excluded hepatic pulsation and dephasing of the two ventricles: amplitude images were used to trace the right and left ventricular zones of interest. The ratio of right to left ventricular ejection fraction was calculated in these zones from the radioactive count at end diastole and end systole. The ratio of the ejection fractions was 1.15 +/- 0.18 in subjects without valvular disease compared to 2.66 +/- 0.47 in patients with mitral regurgitation and normal coronary arteries, and 2.50 +/- 1.28 in mitral regurgitation with coronary artery disease (no significant difference between these two sub-groups). When compared with angiographic quantification of the mitral regurgitation, the ratio of ejection fractions increased progressively with the severity of the leak: 1.81 +/- 0.44 for grade I (9 cases), 2.37 +/- 0.80 for grade 2 (5 cases), 3.02 +/- 1.07 for grade 3 (4 cases) and 3.73 +/- 1.50 for grade 4 (5 cases). The differences between each sub-group are not statistically significant because of the small number of patients in each sub-group but all the values are significantly higher than the reference values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Beat-to-beat assessment of left ventricular ejection in atrial fibrillation.

Beat-to-beat left ventricular ejection was evaluated in a group of 20 patients with chronic atrial fibrillation using a computerized single probe detector. The reference group consisted of 10 patients with sinus rhythm. For each patient 30 successive cardiac cycles were analyzed and the relative variations of four parameters were assessed: R-R interval, diastolic and systolic time intervals, and ejection amplitude, corresponding to the left ventricular stroke volume. The mean variations were respectively 3.4%, 10.4%, 8.4%, and 11.8% in patients with sinus rhythm, and 21.9%, 37.9%, 10.6% and 30.5% in patients with atrial fibrillation. This demonstrates that changes in ejection are mainly related to the duration of the filling phase, with nearly constant systolic times. Correlations between R-R intervals and systolic ejection amplitudes were highly significant (P less than 0.001) in patients with atrial fibrillation in 85% of cases. This information complements the average ejection fraction obtained from multiple cycle superimposition.

Adult↗
PubMed1983

Negative lung thallium-201 uptake in right ventricular infarction.

In a case of right ventricular infarction, a negative lung image was observed on the resting thallium-201 scan, with a pulmonary activity much lower than the surrounding background. The myocardial image showed only a moderate inferior hypoactivity and the left ventricular ejection fraction was normal. This seems to be related to right ventricular failure with normal left ventricular function. It represents the opposite mechanism to the increased pulmonary thallium uptake commonly seen in severe left ventricular impairment.

Aged↗
PubMed1982

Determination of organ volume by single-photon emission tomography.

A method for estimation of organ volume is proposed, based on analysis of individual slices obtained from SPET images. In a phantom simulating clinical circumstances, the data show that the level a threshold at 46% of the maximum activity predicts most closely the true volume over a wide range above one liter. The level at 45% predicted better volumes of less than one liter. For phantoms of 839 ml or less, the error was 6.3 ml (one standard error of estimation). This level seems to be independent of the plane or position of the phantom and also independent of the amount of scattering material around it. Nonradioactive voids ("holes") within a phantom may be included or excluded at will when their edges are not tangent to the edge of the phantom. In such cases, their edges are not distinguishable from the edge of the phantom and their volumes are excluded. Knowledge of organ volumes has both diagnostic and therapeutic importance and could lead to a more precisely quantitated total of the radioactivity contained in an organ or space.

Models, Structural↗
PubMed1981

[Initial results of dynamic gamma-tomography of heat cavities].

After blood pool labeling using technetium albumin, 32 scintigraphic projections are recorded by means of a rotating gamma-camera. An electrocardiographic multi-gating acquisition procedure selects the dynamic pictures during the cardiac cycle of the patient. The computer processing of this set of data and the reconstruction of multiple tomographic slices through the thorax allow a precise kinetic analysis of the cardiac walls.

Electrocardiography↗
PubMed1980

[Study of dynamics and left ventricular function using radioisotopic technics in the heart cavities].

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.

Animals↗
PubMed1980

[Isotopic methods and primary congestive cardiomyopathies].

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.

Adolescent↗
PubMed1978

Topograhic relation between the myocardial uptake of radiothallium and left ventricular kinetics in myocardial infarction.

Myocardial images with thallium 201 are recorded on a computer with the ECG tracing and the cardiac cycle divided into 16 consecutive images. The patients then recieve 99Tcm albumin for first pass and a subsequent ECG gated series for comparison with the myocardial studies. These images can be superimposed and allow the topographic relationships of thallium uptake and ventricular contractility as reflected by the blood pool, to be seen. Quantitative parameters such as ejection fraction and stroke volume are also obtained. Examples in clinical practice are given.

Adult↗
PubMed1978

The contribution of nuclear medicine and ultrasounds in cardiac surgery.

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.

Angiocardiography↗