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J C Cardot

Publications and source records attributed to J C Cardot.

32 records · Page 2Linked to original sources
PubMed1985

[Determination of ventricular volumes by a non-geometric method using gamma-cineangiography].

The authors suggest a new way of determining ventricular volume by a non-geometric method using gamma-cineangiography. The results obtained by this method were compared with those obtained by a geometric methods and contrast ventriculography in 94 patients. The new non-geometric method supposes that the radioactive tracer is evenly distributed in the cardiovascular system so that blood radioactivity levels can be measured. The ventricular volume is then equal to the ratio of radioactivity in the LV zone to that of 1 ml of blood. Comparison of the radionuclide and angiographic data in the first 60 patients showed systematic values--despite a satisfactory statistical correlation (r = 0.87, y = 0.30 X + 6.3). This underestimation is due to the phenomenon of attenuation related to the depth of the heart in the thoracic cage and to autoabsorption at source, the degree of which depends on the ventricular volume. An empirical method of calculation allows correction for these factors by taking into account absorption in the tissues by relating to body surface area and autoabsorption at source by correcting for the surface of isotopic ventricular projection expressed in pixels. Using the data of this empirical method, the correction formula for radionuclide ventricular volume is obtained by a multiple linear regression: corrected radionuclide volume = K X measured radionuclide volume (Formula: see text). This formula was applied in the following 34 patients. The correlation between the uncorrected and corrected radionuclide volumes and the angiographic volumes was improved (r = 0.65 vs r = 0.94) and the values were more accurate (y = 0.18 X + 26 vs y = 0.96 X + 1.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Factors influencing the quantification of valvular regurgitation by gated equilibrium radionuclide angiography.

To test the clinical validity of the stroke volume ratio (SVR) and the factors influencing its value we determined it in a population of 41 patients free of valvular regurgitation. The SVR was estimated from multigated blood pool scans in left anterior oblique position by two methods. The first method followed the classical formula of the left to right ventricular stroke count ratio. The second method used the same formula except that the right atrial activity emanating from the area of right atrioventricular overlap as traced at right ventricular end-systole, was subtracted from the right ventricular stroke count. The SVR averaged 1.25 +/- 0.18 (range 0.97-1.80) by the first technique and 1.05 +/- 0.12 (range 0.82-1.36) by the second (P less than 0.001). In our results the SVR is not correlated to either ejection fraction or angiographically determined left ventricular volumes. Conversely the SVR is correlated with the left to right end-diastolic volume ratio evaluated from radionuclide counts measured at right and left ventricular end-diastole (r = 0.48, P less than 0.01). This may be due to variations in the area of right atrioventricular overlap, depending on the size of the ventricular chamber. It is postulated that the accuracy of SVR determination could be enhanced by subtraction of the right atrial activity from the right ventricular activity at end-systole. In patients free of valvular regurgitation the LV/RV stroke volume ratio approaches unity and the variability of the results is smaller. Interobserver and intraobserver variability is reduced using the Fourier phase approach.

Aortic Valve Insufficiency↗
PubMed1984

[Method of isotopic determination of aortic valve regurgitation].

The index of valvular regurgitation was measured by two techniques after technetium 99 m gamma-cineangiography: the classical technique of comparing left and right ventricular stroke volumes, and the same technique after subtracting the radioactivity arising from the right atrium from the zone of right atrioventricular superposition. The index of valvular regurgitation was calculated in 41 patients with chronic coronary artery disease without valvular regurgitation and also undergoing coronary angiography with 30 degrees right anterior oblique ventriculography, in 8 healthy volunteer subjects, at rest and on exercise; and in 15 patients with chronic aortic regurgitation also undergoing cardiac catheterization and 30 degrees right anterior oblique left ventriculography and aortography. The regurgitant index by the classical technique was 1,25 +/- 0,18; when the index was calculated again after subtracting right atrial radioactivity, a value of 1,05 +/- 0,12 (p less than 0,01) was obtained. The regurgitant index is not affected by left ventricular contractility or by the degree of left ventricular dilatation. On the other hand, this index is affected by the degree of right ventricular dilatation. The valvular regurgitant index did not vary significantly on exercise (1,01 +/- 0,11 to 1,17 +/- 0,16 NS). The isotopic regurgitant fraction deduced from the valvular regurgitant index correlated well with the angiographic regurgitant fraction (R = 0,74; p less than 0,001). The index of valvular regurgitation gives an exact, reliable and reproducible quantification of left sided regurgitant lesions. It is only valid when there is no intracardiac shunt or regurgitant right heart lesion.

Aortic Valve Insufficiency↗
PubMed1983

[Analysis of the rebound phenomenon during outflow in plethysmography following programmed venous occlusion].

The venous outflow curve obtained using strain gauge plethysmography (Periflow JSI) frequently displays a slope change which modifies the classic exponential pattern: The semi-continuous arterial blood flow measurement together with an ECG-triggered plethysmography let the authors show the arterial origin of this slope change they called "the rebound phenomenon". Venous occlusion induces an ischemia which creates a reactive hyperemia when the venous blood current is let free. All the venous outflow curves stem from both a venous and arterial phenomenon. This latter may sometimes be of importance and has to be considered in plethysmography studies.

Adult↗
PubMed1982

Temporal Fourier analysis applied to equilibrium radionuclide cineangiography. Importance in the study of global and regional left ventricular wall motion.

Regional and global left ventricular wall motion was assessed in 120 patients using radionuclide cineangiography (RCA) and contrast angiography. Functional imaging procedures based on a temporal Fourier analysis of dynamic image sequences were applied to the study of cardiac contractility. Two images were constructed by taking the phase and amplitude values of the first harmonic in the Fourier transform for each pixel. These two images aided in determining the perimeter of the left ventricle to calculate the global ejection fraction. Regional left ventricular wall motion was studied by analyzing the phase value and by examining the distribution histogram of these values. The accuracy of global ejection fraction calculation was improved by the Fourier technique. This technique increased the sensitivity of RCA for determining segmental abnormalities especially in the left anterior oblique view (LAO).

Adult↗
PubMed1981

Scintigraphic image contrast-enhancement techniques: global and local area histogram equalization.

This article develops two contrast-modification techniques for the display of scintigraphic images. Based on histogram-modification techniques, histogram equalization, where each level of gray is used to the same extent, gives maximum entropy. The first technique uses the application of histogram equalization in the whole image. To eliminate contrast attenuation small but important portion of the gray scale histogram, local area histogram equalization has been applied to images with differences in intensity. Both techniques were tested using a phantom with known characteristics. The global equalization technique is more suitable to bone scintigraphies, and some well-chosen boundaries improved the difference between two comparable areas. For liver scintigraphies, where intensity is quite equal in every pixel, a local area equalization was chosen that allowed detection of heterogeneous structures. The images resulting from histogram-equalization techniques improve the readability of data, but are often far from usual images and necessitate an apprenticeship for the physician.

Bone and Bones↗
PubMed1981

[Comparison of 2 methods of determining the kinetics of a bicompartmental system. Application to the measurement of cutaneous blood flow].

Peeling method and a non linear regressions method (Newton's method) have been tested on experimental and simulated data. Newton's method is the most accurate and precise when running on simulated data. Experimental curves artefacts make Newton's algorithm automatically running less efficient than classical peeling algorithm working in interactive mode.

Blood Flow Velocity↗
PubMed1979

[Cutaneous and subcutaneous blood flow measurement in rabbit's ear by epicutaneous diffusion of xenon 133. Influence of the arteriovenous anastomosis].

The cutaneous and subcutaneous blood flow measurement by a diffusible inert gas concerns theorically capillary nutritional flow. In clinical routine, where pathological openning of arteriovenous anastomosis is suspected, the blood flows measured by Xenon technic are often increased. The function of the shunts are displayed on the epuration curve obtained on a region where there are numerous: rabbit's ear.

Animals↗