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C Raynaud

Publications and source records attributed to C Raynaud.

At least 55 records · Page 3Linked to original sources
PubMed1982

An analytical approach to single photon emission computed tomography with the attenuation effect.

The problem of transverse plane reconstruction from an ensemble of projections is considered in its general formulation and an analytically exact solution to the attenuated tomographic operator is proposed. Such a technique, called the regularizing iterative method (RIM), allows the introduction of a priori knowledge on the size and shape of the activity distribution and in principle on the exact attenuation distribution. The relaxation factor used is so named because it provides noise filtering for a small number of iterations. The effectiveness of RIM was studied in the single photon emission computed tomography (SPECT) problem with the aim of correcting for attenuation before quantitative study. Its application involves the use of a rotating scintillation camera connected to a mini-computer system. Various mathematical and physical phantoms were studied, and a satisfactory attenuation correction was always obtained in the final image with an improvement in the contrast and signal-to-noise ratio. Preliminary clinical studies on liver transverse sections seems to indicate an improvement in deep lesion detectability, compared with images obtained by the filtered (Ramp) back projection technique.

Models, Structural↗
PubMed1982

In vivo distribution of carrier protein/67Ga-complexes.

The uptake of 67Ga as citrate, chloride and complexed by carrier-proteins (lactoferrin and transferrin) has been studied in tumor- and inflammatory lesion-bearing rats. Different uptake patterns are shown by tumors and lesions. 67Ga-transferrin complexes are taken up to the highest extent by tumors and inflammatory lesions. The comparative distribution studies using normal animals indicate a systemic increase of 67Ga uptake by tumor- and lesion-bearing animals which might be of importance in explaining the mechanism of 67Ga accumulation. The role of ionic environment changes and radioactivity concentration by isomorphous ionic replacement is discussed.

Animals↗
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

Radioruthenium -- 2,3-Dimercaptopropansulfonic acid complex. A potentially useful radiocompound for kidney studies.

Radioruthenium complexed with 2,3-dimercaptopropansulfonic acid (DMPSA) shows a preferential localization in kidneys. After studying several parameters with regard to their influence on renal incorporation, the optimal procedure was established, showing an uptake by kidney (for 97Ru-labelled compound) of 30.3% dose/g/24 h or 43.4% dose/organ/24 h. The highest accumulation was reached 7-10 h after iv injection and no significant elimination was observed 24 h thereafter. The probable mechanisms involved in this process are discussed.

Animals↗
PubMed1978

New developments in renal physiopathology acquired using a quantitative renal functional test: the 197Hg uptake test.

The renal function of 331 obstructive uropathies, of which 112 were unilateral, were studied using the radioactive Hg renal uptake technique. The results obtained lead to the following observations: (1) Kidneys silent because of a chronic pelviureteric obstruction maintain a minimum function representing approximately one quarter of the normal value, which does not seem to be improved following the removal of the obstruction. (2) Operative relief of obstruction in unilateral obstructive uropathy, except for cases of silent kidneys, is followed by a significative improvement in the function of the kidney on the operated side in more than a third of the cases studied. (3) In 43% of obstructive uropathies considered as unilateral, the functional value of the two kidneys is decreased.

Adolescent↗