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Theses

ETUDE DE LA PERFUSION EN ECHOGRAPHIE DE CONTRASTE

Abstract : GROWING INTEREST IS SHOWN TOWARD CONTRAST ULTRASOUND FOR PERFUSION ESTIMATION. HOWEVER, QUANTIFICATION CURRENTLY REMAINS OUT OF REACH BECAUSE OF VARIOUS PROBLEMS. INDEED, RESPIRATORY MOTION OR ACQUISITION MOTION OFTEN IMPAIR THE IMAGE SEQUENCES ACQUIRED AND THE COMPLEX RELATION BETWEEN THE SIGNAL DISPLAYED IN IMAGES AND THE CONCENTRATION OF THE ULTRASOUND CONTRAST AGENT (USCA) IS STILL UNCLEAR. THIS WORK PROPOSES TO HELP TO IDENTIFY THE VARIOUS CONTRAST UPTAKE KINETICS TAKING PLACE IN CONTRAST ULTRASOUND IMAGE SEQUENCES USING THE FACTORIAL ANALYSIS OF MEDICAL IMAGES SEQUENCES (FAMIS). THIS METHOD ALLOWS TO IDENTIFY PERFUSION DEFICITS AS WELL AS ATTENUATION ARTIFACTS OF THE INCIDENTAL ACOUSTIC WAVE DUE TO USCA (SHADOWING) IN BRAIN CONTRAST ULTRASOUND EXAMINATIONS. FAMIS ALSO SHOWS THE INFLUENCE OF RESPIRATORY MOTION IN HEPATIC OR SMALL ANIMAL PERFUSION SEQUENCES. A COMPENSATION OF THIS MOTION IS PROPOSED, SYNCHRONIZING THE IMAGES ON THE RESPIRATORY CYCLE. THIS IS DONE A POSTERIORI, USING TWO DIFFERENT CRITERIA: A STATISTICAL INDEPENDENCE CRITERION AND A FREQUENCY CRITERION. THIS SYNCHRONIZATION MAKES IT POSSIBLE TO OBTAIN IMAGE SEQUENCES CONTAINING FEW RESIDUAL MOTIONS AND TO BE FREED FROM OUT OF PLANE MOTION ARTIFACTS. IN ORDER TO COMPENSATE THE SHADOWING ARTIFACTS, USCA IN VITRO CARACTERISATION WAS CONSIDERED. HARMONIC BACK-PROPAGATION AND ATTENUATION COEFFICIENTS HAVE BEEN MEASURED AS A FUNCTION OF MECHANICAL INDEX AND UCSA CONCENTRATION. A SIMPLE SOLUTION FOR COMPENSATING SHADOWING IS PROPOSED FOR BRAIN CONTRAST ULTRASOUND SEQUENCES. THIS WORK CONSTITUTES A FIRST STEP IN ORDER TO BETTER UNDERSTAND AND COMPENSATE FOR QUANTIFICATION ARTIFACTS IN CONTRAST ULTRASOUND.
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https://tel.archives-ouvertes.fr/tel-00012175
Contributor : Gilles Renault <>
Submitted on : Monday, April 24, 2006 - 3:39:48 PM
Last modification on : Friday, October 23, 2020 - 4:38:30 PM
Long-term archiving on: : Monday, September 17, 2012 - 1:45:42 PM

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  • HAL Id : tel-00012175, version 1

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Gilles Renault. ETUDE DE LA PERFUSION EN ECHOGRAPHIE DE CONTRASTE. Physique [physics]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00012175⟩

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