Analysis of multiple scattering suppression using structured laser illumination planar imaging in scattering and fluorescing media.

The accuracy, precision and limitations of the imaging technique named Structured Laser Illumination Planar Imaging (SLIPI) have been investigated. SLIPI, which allows multiply scattered light to be diminished, has previously demonstrated improvements in image quality and contrast for spray imaging. In the current study the method is applied to a controlled confined environment consisting of a mixture of water and monodisperse polystyrene microspheres. Elastic scattering and fluorescence are studied and the results obtained when probing different particle concentrations and diameters conclusively show the advantages of SLIPI for imaging within moderately turbid media. Although the technique presents both good repeatability and agreement with the Beer-Lambert law, discrepancies in its performance were, however, discovered. Photons undergoing scattering without changing their incident trajectory cannot be discriminated and, owing to differences in scattering phase functions, probing larger particles reduces the suppression of multiply scattered light. However, in terms of visibility such behavior is beneficial as it allows denser media to be probed. It is further demonstrated that the suppression of diffuse light performs equally well regardless of whether photons propagate along the incident direction or towards the camera. In addition, this filtering process acts independently on the spatial distribution of the multiply scattered light but is limited by the finite dynamic range and unavoidable signal noise of the camera.

Some safety procedures for handling 32P during postlabelling assays.

32P is a high-energy (1.7 MeV) beta-emitter. Its handling is therefore subject to regulation and very strict control. During the postlabelling procedure, numerous steps involve exposure to 32P. The main risk from exposure is through irradiation, but direct accidental contamination can occur. The various manipulation steps (ATP synthesis, labelling, chromatography, quantification) have been analysed for their contribution to potential radiation exposure. Several measures have been taken in the IARC laboratories to minimize exposure of all personnel involved, including those who handle radioactive wastes, since most of the initial radioactivity is eventually discarded. The various steps to be taken for minimizing exposure, such as the training of personnel using fluorescent compounds instead of radioactivity, the use of protective screens and of equipment specially adapted for this work, are reviewed.

Quantitative assessment of valvular regurgitations using the pulsed Doppler technique. Approach to the regurgitant lesion.

It is now possible with pulsed Doppler to grade the severity of aortic, mitral and tricuspid regurgitations on a quantitative basis. "Indices" were devised, using the measurement of the spatial extent of abnormal Doppler signals. For aortic regurgitation: (1) at the aortic valvular orifice area, by measurement of the regurgitant aortic valvular area and calculation of the valvular regurgitant "index". (2) In the left ventricle outflow tract, by calculation of an "index" combining information from two echographic (short and long axis) planes. For mitral regurgitation: by calculation of the total regurgitant "index" combining information from examination of the annulus in short axis, and of the left atrium in long axis view. For tricuspid regurgitation: at the tricuspid annulus, by averaging the depth of the reversal wave on two samples recorded using various echographic approaches. A group of patients with aortic (42), mitral (55) and tricuspid (57) regurgitation proven by invasive procedures, was investigated with this procedure using a 3 MHz two dimensional pulsed Doppler echo device. Correlative coefficients between the Doppler grading and that provided by independently performed invasive procedures on a three point scale, ranged between 0.66 and 0.88, with significant differentiation of mean values of indices (P less than 0.01 to P less than 0.001) for each grade of severity. Success in the Doppler grading of severity of the regurgitations requires (1) a sampling as close as possible to the lesion, and optimally at ther very site of the lesion, (2) the largest explorable area at the site of the lesion, (3) the relevancy of the selected Doppler parameter in order to take into account, as much as possible, the three dimensional configuration of the regurgitant jet. Moreover, this mapping procedure provides a pathophysiological insight of the regurgitant lesion for left-sided regurgitations.

Anatomic and functional evaluation of pure and associated mitral stenoses using the echo-Doppler scanner technique.

Twelve normal subjects, 18 control patients and 25 patients with mitral valve lesions (MVL), including 10 pure stenoses (MS), and 15 associated regurgitations (MS + MR) were investigated using a 2-dimensional (2D) pulse echo Doppler procedure, the latter group before open heart surgery. The Doppler signal output consisted of an audio-signal and of a graphic display including an analogue flow velocity trace and a frequency spectrum (Time Interval Histogram). The investigation was two-fold. (1) Diagnosis and assessment of severity of MVL comparing 2D echo and Doppler reliability. The main criteria for diagnosis relied, firstly for the 2D pulsed echo technique on the determination of the planimetric mitral valve area (MVA) for MS and on the finding of an increased annulus diameter for MR, and secondly for the Doppler technique, on the detection of diastolic (MS) and systolic (MR) anomalies of the mitral flow velocity patterns. (2) 2D echo-cardiographic assessment of the mitral apparatus (valves, annulus, subvalvular apparatus), studied on the basis of quantitative and qualitative data. Independently performed correlations with catheterization, angiographic and surgical data showed that a positive diagnosis of MS was obtained in all cases, both with 2D echo and Doppler techniques with a specificity of 92% for the former and 96% for the latter. The assessment of the severity of lesions was satisfactory in 88% of cases for the Doppler, and in 80% of cases for the 2D echo technique with a linear correlative coefficient at 0.83 for the value of MVA measured at catheterization and echocardiography. For MR, a net advantage in diagnosis was found for the Doppler technique (sensitivity of 93%, specificity of 92%) as compared with the 2D echo technique (sensitivity of 33%, specificity of 82%), and also for the assessment of the severity (60% for 2D echo and 85% for Doppler). Furthermore, Doppler assessment of the site of regurgitation and of the direction of the regurgitant jet was in agreement with all the cases also submitted to invasive investigations. Quantitative data obtained by the 2D echo technique for the assessment of the annulus diameter, and of the quality of mitral valve tissue (pliable, fibrous, calcified) or subvalvular apparatus (discrete, moderate, severe alterations), significantly differentiated normals from patients, but no clear-cut separation appeared for patients between close types of alterations. A better assessment was achieved from qualitative data for mitral valve tissue (76% of cases), and subvalvular apparatus (84% of cases).

Non-invasive diagnosis and assessment of tricuspid regurgitation and stenosis using one and two dimensional echo-pulsed Doppler.

Twenty normal subjects and 82 patients with valvular heart disease, whose lesions were independently assessed either by cardiac catheterisation and/or at operation, were studied using the pulsed Doppler technique combined with either one or two dimensional echocardiography. Of these, 41 patients had tricuspid lesions, including 40 with regurgitation and nine with stenosis. The tricuspid analogue flow velocity trace and the Doppler frequency spectrum (time interval histogram) were recorded. Characteristic differences were found between the records from subjects with and without tricuspid lesions. In subjects with tricuspid regurgitation there was a systolic negative wave on the analogue velocity display and broadening of the time interval histogram. In subjects with tricuspid stenosis there was an abnormal pattern, and significantly increased duration of the diastolic wave on the analogue velocity trace, again with broadening of the time interval histogram. Sensitivity and specificity ranged between 85 and 95%. The calculated ratio between the measured amplitudes of the systolic and diastolic waves correlated well with independently performed grading of the regurgitation on a three point scale in 85% of cases. Grading of the severity of tricuspid stenosis on a three point scale based on studies of the diastolic Doppler velocity anomalies was the same in 85% of cases as the grading based on established invasive techniques. The addition of two dimensional echocardiography to the pulsed Doppler technique increased the sensitivity for mild lesions.

[Hemodynamic effects of intravenous injections of amiodarone chlorhydrate in normal subjects and coronary patients]. / Effets hémodynamiques de l'injection intra-veineuse de chlorhydrate d'amiodarone chez le sujet normal et le coronarien

A study has been made of the haemodynamic affects of a single intravenous injection of amiodarone chorhydrate (5 mg/kg); the injection was given at rest to six normal subjects and six patients with coronary insufficiency due to atherosclerosis. The effects of the drug are most marked at the fifteenth minute after injection, and are: slowing of the heart rate; lessened cardiac output and left ventricular effort; a significant increase in mean pulmonary arterial pressure and diastolic pressure; slight variations in flow in the coronary sinus, with an increase in the ratio of coronary sinus flow to cardiac output. Amiodarone chlorhydrate appears to exert a favourable action upon the heart because, while it maintains myocardial perfusion, it tends to diminish the myocardial oxygen requirement by decreasing the rate of contraction and the contractility of the myocardium.