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Gateau, Jérôme. "Imagerie ultrasonore ultrarapide d'évènements de cavitation : application en thérapie par ultrasons et imagerie de détection". Phd thesis, Université Paris-Diderot - Paris VII, 2011. http://pastel.archives-ouvertes.fr/pastel-00863591.
Pełny tekst źródłaBarrère, Victor. "Thermométrie Ultrasonore et caractérisation tissulaire durant les traitements par Ultrasons Focalisés de Haute Intensité par méthodes ultrasonores et élastographie passive". Electronic Thesis or Diss., Lyon, 2019. http://www.theses.fr/2019LYSE1348.
Pełny tekst źródłaHigh Intensity Focused Ultrasound (HIFU) is a noninvasive technique allowing generating a temperature increase away from the emitter. This technique is already used in clinic for the treatment of many pathologies such as essential tremors, cancers of the prostate, liver, pancreas, uterine fibroid, glaucoma etc. An imaging modality is required to effectively guide and monitor non-invasive HIFU treatments. Today, magnetic resonance imaging (MRI) and B-mode imaging are the main techniques used in combination with HIFU to guide treatment. MRI is superior to ultrasound for visualizing tissue temperature and necrosis, but this technique is extremely expensive and lacks portability, availability, and present compatibility issues with patients and devices. Ultrasonic imaging has advantages in terms of cost and portability, availability and present good spatial and temporal resolution. Conventional ultrasound imaging shows the spatial amplitude distribution of echoes reflected by acoustic impedance inhomogeneities in the medium and is already widely used to guide and monitor HIFU treatments in commercial devices. However, ultrasound imaging provides limited information on the formation of HIFU coagulation necrosis, and doesn’t allow thermometry. In most cases, hyperechos are visible due to microbubbles generated by acoustic cavitation or boiling. However, these hyperechoic zones do not allow precise contouring of the treated area, and they do not appear during the coagulation. Several methods have been proposed to characterize the thermal changes as a function of other parameters, such as ultrasonic backscatter. Tissue elasticity has also been studied, based on the fact that the tissues become stiffer when they are coagulated. In this thesis, we investigated the changes in backscattered energy by tissue treated by ultrasound due to thermal coagulation without the generation of microbubbles between 37°C and 80°C. The measurements, particularly focused on the energy of the backscattered signal, have been performed for the monitoring of treatments between 1 and 2.9 MHz. Quantitative ultrasounds methods have been performed to reveal information on the microstructure of tissues, in order to explain the phenomena inducing the changes in the backscattered signals during a HIFU heating. A chapter focuses on the monitoring of ultrasonic interventions by passive elastography. Finally, the characterization devices and techniques used in these works were used to characterize liver tissue derived from standard hepatectomies and containing primary and secondary tumors in terms of attenuation. The impact of the different attenuations between the two types of tumor tissue was evaluated by numerical simulations of HIFU treatments. The results led to conclusions about the need for different treatments for primary and secondary cancers in the liver
Ternifi, Redouane. "Mesure de la pulsatilité naturelle du tissu cérébral par ultrasons". Thesis, Tours, 2014. http://www.theses.fr/2014TOUR3306/document.
Pełny tekst źródłaThe study of biological tissues movement is currently, one of the major thematics in the medical imaging field. The challenge is to provide additional clinical information and allow for diagnostic assistance. The recently introduced elastographic techniques, provide ample opportunities for biomechanical tissues characterization, particularly of cerebral tissues. An innovative passive-elastographic methodology for assessing mechanical properties of brain tissue is proposed. The eventual aim is to allow for the diagnosis of neurodegenerative diseases
Sivadon, Audrey. "Contributions à l’imagerie passive de la cavitation ultrasonore : formation de voies adaptatives en 3D et extension spatiale de nuages de bulles". Electronic Thesis or Diss., Lyon 1, 2022. http://www.theses.fr/2022LYO10172.
Pełny tekst źródłaPassive imaging relies on beamforming algorithms that require large aperture probes to provide good axial resolutions; however, in 3D passive imaging, the matrix probes currently marketed do not meet this constraint. Moreover, these probes have a large number of elements, which makes their use particularly unwieldy. This thesis work focuses on the study and improvement of passive cavitation imaging by addressing two aspects in particular: (i) the practical and efficient implementation of 3D passive imaging, (ii) the problem of imaging large sources such as cavitation clouds. We have combined the application of sparse methods (to reduce the number of active elements of the probe used) and the transposition from 2D to 3D of adaptive algorithms in the frequency domain. This formalism uses the robust estimation of the inter-spectral density matrix (CSM) and allowed us to implement simply and efficiently different algorithms: Delay-And-Sum (DAS), Robust-Capon-Beamformer and Pisarenko. The efficiency of these algorithms in 3D has been tested in terms of width to half height, contrast and position error, on a point source in simulations and on a point reflector in experiments. Finally, in order to address the reality of cavitation clouds, we have investigated the behavior of these reconstruction methods in the case of extended sources. Our 2D simulations show the evolution of the reconstructed images as a function of the cavitation cloud characteristics. This work provides a concrete solution for a simple implementation of 3D passive imaging as well as answers to the expectations on the localization and characterization of a cavitation cloud
Asquier, Nicolas. "Etude des moyens de caractérisation de l’ouverture de la barrière hémato-encéphalique induite par un dispositif ultrasonore implantable". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1330/document.
Pełny tekst źródłaThe blood-brain barrier (BBB) is a natural protection of the central nervous system. However, it limits the delivery of many drugs to the brain tissues. It can be temporarily disrupted by ultrasound exposure combined with intravenous injection of microbubbles. In this manuscript, BBB disruption with an implantable unfocused ultrasound device is studied. An automatic method for quantifying the volume of BBB disruption using MR images from a phase 1/2a clinical study in patients with reccurent glioblastoma was assessed and validated. A correlation between the probability of disruption and the local acoustic pressure was found. Microbubbles cavitation activity was studied in vitro to better understand its effect on BBB disruption. The uncertainty on the amplitudes of cavitation signals recorded with a passive single-element detector (PCD) through the skull was quantified. A position-based correction of the PCD signal was assessed and validated. The effect of the volume of a cavitation cloud in the unfocused ultrasound field on the signal amplitude recorded by the PCD during the clinical treatment was discussed. Two methods for localizing and discriminating cavitation sources in a transcranial context were evaluated by simulations and in vitro
Asquier, Nicolas. "Etude des moyens de caractérisation de l’ouverture de la barrière hémato-encéphalique induite par un dispositif ultrasonore implantable". Electronic Thesis or Diss., Lyon, 2019. https://n2t.net/ark:/47881/m6rn376t.
Pełny tekst źródłaThe blood-brain barrier (BBB) is a natural protection of the central nervous system. However, it limits the delivery of many drugs to the brain tissues. It can be temporarily disrupted by ultrasound exposure combined with intravenous injection of microbubbles. In this manuscript, BBB disruption with an implantable unfocused ultrasound device is studied. An automatic method for quantifying the volume of BBB disruption using MR images from a phase 1/2a clinical study in patients with reccurent glioblastoma was assessed and validated. A correlation between the probability of disruption and the local acoustic pressure was found. Microbubbles cavitation activity was studied in vitro to better understand its effect on BBB disruption. The uncertainty on the amplitudes of cavitation signals recorded with a passive single-element detector (PCD) through the skull was quantified. A position-based correction of the PCD signal was assessed and validated. The effect of the volume of a cavitation cloud in the unfocused ultrasound field on the signal amplitude recorded by the PCD during the clinical treatment was discussed. Two methods for localizing and discriminating cavitation sources in a transcranial context were evaluated by simulations and in vitro
Zorgani, Ali. "Passive Elastography : Tomography and Mechanical Characterization of Biological Tissue". Electronic Thesis or Diss., Lyon, 2016. http://www.theses.fr/2016LYSE1191.
Pełny tekst źródłaThe aim of this thesis was the development of a new approach called passive elastography. This approach is inspired from noise correlation methods well developed in seismology and time reversal technics in acoustics. Passive elastography uses shear waves naturally induced in the human body to extract its mechanical properties of soft tissue. The feasibility of this method was tested in several applications. First in ultrasound, slow frame rate ultrasound scanner was used to monitor high intensity focused ultrasound treatment on porcine pancreas. Then, an ultrafast ultrasound scanner was used to retrieve shear wave speed map in a calibrated phantom and in-vivo. Second, Magnetic resonance elastography was implemented to image natural motion in the brain of healthy volunteers and conduct shear wavelength tomography. Third, of ophthalmological and dermatological applications, optical coherence passive elastography was tested in a phantom and a cornea of healthy mouse. Also, a fully optical setup was established to image surface wave for elastography applications. Finally, the resolution limit of elastography was measured using and ultrasound ultrafast scanner
Zorgani, Ali. "Passive Elastography : Tomography and Mechanical Characterization of Biological Tissue". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1191/document.
Pełny tekst źródłaThe aim of this thesis was the development of a new approach called passive elastography. This approach is inspired from noise correlation methods well developed in seismology and time reversal technics in acoustics. Passive elastography uses shear waves naturally induced in the human body to extract its mechanical properties of soft tissue. The feasibility of this method was tested in several applications. First in ultrasound, slow frame rate ultrasound scanner was used to monitor high intensity focused ultrasound treatment on porcine pancreas. Then, an ultrafast ultrasound scanner was used to retrieve shear wave speed map in a calibrated phantom and in-vivo. Second, Magnetic resonance elastography was implemented to image natural motion in the brain of healthy volunteers and conduct shear wavelength tomography. Third, of ophthalmological and dermatological applications, optical coherence passive elastography was tested in a phantom and a cornea of healthy mouse. Also, a fully optical setup was established to image surface wave for elastography applications. Finally, the resolution limit of elastography was measured using and ultrasound ultrafast scanner
Larose, Eric. "Diffusion multiple des ondes sismiques et expériences analogiques en ultrasons". Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10100.
Pełny tekst źródłaThis thesis manuscript is devoted to the study of the seismic and ultrasonic wave propagation in complex media. Two methods are proposed to take advantage of the phase information contained in diffuse waves. 1) Weak localization of seismic waves is observed on a volcano (Auvergne). This field experiment demonstrates the presence of multiple scattering in coda waves, and allows the direct measurement of the transport mean free path of the sub-surface that quantifies the heterogeneities. 2) A passive imaging technique is also proposed : it is based on the correlation of diffuse field or noise, a correlation that yield the elastic or acoustic Green function between passive sensors as if one of them was a source. Initially applied to ultrasonic cavities, this technique is generalized to open scattering media. A physical interpretation based on a Time-Reversal analogyis proposed. The time symmetry of the correlations is studied, with means of numerical simulations, seismic experiment in Alaska, and ultrasonic experiment in the lab using a small medium ana logo us to the Earth's crust. The role of scattering and source position is emphasized. The passive imaging technique is used to perform the tomography of a layered medium, to image of interfaces and localized reflectors. Ln the end this technique is applied to Lunar seismic noise records, acquiered by four geophones emplaced on the Moon during Apollo 17 mission (1972). This last observation demonstrates the feasibility of correlating the noise to image the subsurface on other planets than the Earth which should provide a novel avenue for future extraterrestrial exploration missions
Graciet, Christophe. "Imagerie quantitative par ultrasons de propriétés de matériaux composites". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10574.
Pełny tekst źródłaElbes, Delphine. "Thermothérapies par ultrasons focalisés et radiofréquences guidées par imagerie de résonance magnétique". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14683/document.
Pełny tekst źródłaMy manuscript studies the development of mini and non invasive thermotherapies guided by magnetic resonance imaging (MRI) in the treatment of hepatic and cardiac diseases. The first part was the development of a method to increase the lesion size, induced by HIFU, and based on bubble enhanced heating (BEH). The acoustic power threshold of the BEH was determined by MR acoustic radiation force imaging (MR-ARFI) and the thermal effect was characterized by MR thermometry on ex vivo and in vivo in pig livers. The second part developed a strategy to perform HIFU through the rib cage using beam steering to track the respiratory movement or to performed multipoint ablation while avoiding heating of ribs. Transducer elements localized in the geometric projection of the shadow of ribs, relatively to the targeted focal point, were switched off.The third part was the development of the MR thermometry on the heart for the monitoring of radiofrequency ablation (RFA). Several aspects were investigated, in particular the thermometry precision, the feasibility to perform catheter radiofrequency ablation under MR thermometry in vivo in a sheep heart, the possibility to use the catheter as an MR antenna to increase spatial resolution of MR thermometry images
MARTIN, DIDIER. "Propagation d'ondes et imagerie en milieux anisotropes par laser ultrasons". Paris 7, 1993. http://www.theses.fr/1993PA077185.
Pełny tekst źródłaGâteau, Jérôme. "Imagerie ultrasonore ultrarapide d'événements de cavitation : application en thérapie par ultrasons et imagerie de détection". Paris 7, 2011. http://www.theses.fr/2011PA077013.
Pełny tekst źródłaThe onset of cavitation activity in an aqueous medium is linked to the formation of gas/vapour-filled cavities of micrometric size. This formation can be acoustically mediated and is then called acoustic bubble nucleation. We focus here in the activation of seed nucléi by short (a few cycles) and high amplitude ultrasonic excitation (order of magnitude MPa). Bubbles are generated during the rarefaction phase of the wave and are transient (they dissolve). The nucleation properties of biological tissues are little known. However, they can be assessed using ultrasound: the formation of a bubble results in the appearance of a new scatterer (which can be detected with a pulse-écho detection), and each cavitation event generates an acoustic emission (detected with passive reception). In n this PhD manuscript, we use ultrafast ultrasound imaging (simultaneous acquisition on an array of transducers with a high frame rate) to detect cavitation events. Two in vitro applications were first validated. On one hand, bubble nucleation was performed through a human skull, and transcranial passive detection of a single cavitation event was used in a time reversal process to optimize adaptive focusing for thermal therapy of brain tissue. On the other hand, the formation and dissolution of bubbles in scattering biological tissues (muscle) were detected with a high sensitivity by combining passive detection and ultrafast active imaging. Finally, in vivo experiments on sheep's brain, and others in vitro on animal blood showed that nucleation in biological tissue is a random phenomenon, and high negative pressure are mandatory to initiate nucleation in vivo (< -12MPa)
Roux, Christian. "Evaluation de l'os humain par ultrasons : application à l'ostéoporose". Compiègne, 1997. http://www.theses.fr/1997COMP1049.
Pełny tekst źródłaGesnik, Marc. "Imagerie fonctionnelle par ultrasons de la rétine et des fonctions visuelles cérébrales". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLET011/document.
Pełny tekst źródłaThis thesis focuses on recent improvements in the functional ultrasound imaging (fUS) technique and their applications in the field of ophthalmology. Within the framework of a synergetic project blending waves physics, medical imaging, neuroscience and ophthalmology, fUS was shown to be capable of imaging and studying the visual system of healthy and diseased animals for the purpose of preclinical studies. To tackle these issues, constant upgrades in the fUS technique had to support the preclinical studies.An experimental set-up was built to image the visual pathway in three dimensions with fUS. Using a new imaging facility, fUS was proven to be feasible in real time and at high ultrasound frequencies such as 30 MHz. Interleaved sampling had to be implemented in that case. Furthermore, the a priori knowledge of the vascular cerebral architecture and the Doppler Effect were exploited to spectrally decompose cerebral blood flux and vessels according to their velocities and orientations.Leveraging these improvements, functional ultrasound imaging of rats and non-human primates was performed. Primate retina was imaged with Power Doppler, but proved to be too mobile to be functionally imaged. However, fUS has been performed on rat retina after 30 MHz fUS imaging had been implemented. The rat visual pathway has then been characterised with fUS. Some of its known features where highlighted such as its retinotopic organisation or the time response differences between some of its structures. The same set-up has been leveraged to map the cerebral activity of animal that underwent visual restauration therapies. These tools were then used to map cerebral activity in anesthetized and awake and behaving monkeys. Unique blood volume variations due to unique mistakes were detected. These tools were finally applied to two preclinical trials on a depressive state of the brain vascular contractility. Blood volume and blood velocity changes were highlighted throughout an acute and a chronical study
Sandrin, Laurent. "Elastographie impulsionnelle par ultrasons : du palpeur acoustique à l'imagerie ultrarapide". Paris 6, 2000. http://www.theses.fr/2000PA066538.
Pełny tekst źródłaSouchon, Rémi Chapelon Jean-Yves. "Application de l'élastographie à l'imagerie du cancer de la prostate et à sa thérapie par ultrasons focalisés rostate cancer detection and HIFU therapy monitoring using elastography /". Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=souchon.
Pełny tekst źródłaThèse rédigée en anglais. Introduction et conclusion en français et en anglais. Titre provenant de l'écran-titre. Bibliogr. p. 113-118. Publications de l'auteur, 3 p.
Macé, Emilie. "Développement d'une nouvelle modalité d'imagerie fonctionnelle cérébrale et étude de l'élasticité du cerveau par ultrasons". Paris 7, 2012. http://www.theses.fr/2012PA077212.
Pełny tekst źródłaIn this thesis, we investigate the possible contribution of ultrafast ultrasound imaging in neuroimaging. Ultrafast imaging is a technique using plane wave emissions to acquire ultrasonic images at high frame rate (~ 20 kHz). First, we developed a new brain functional imaging modality called functional ultrasound (fUS) that can image the whole brain at high spatiotemporal resolution (100 μm, 200 ms). For that, we combined ultrafast imaging and synthetic focusing in emission to increase the sensitivity of Doppler imaging by a factor 100 and thus to detect blood flow in cerebral microvessels whose dynamics is linked to local neuronal activity. We validated fUS by mapping in vivo the brain activation induced by various sensory stimuli. Then, we were able to follow by fUS the dynamics of an epileptic seizure, a pathology very challenging for imaging up to now. Finally, we designed a fUS sequence with higher temporal resolution (30 ms) to observe the effect of pulsatility on cerebral blood flow. In a second step, we adapted the "Supersonic Shear Imaging" technique based on ultrafast imaging to map brain elasticity. We then applied it to a rat model of transient cerebral ischemia. We observed for the first time the softening of ischemic tissue and, simultaneously, we followed the stroke impact on brain microvascularization with our new Doppler mode. These new modes are promising not only in neuroscience research but also for their clinical applications in pediatry and neurosurgery
Souchon, Rémi. "Application de l'élastographie à l'imagerie du cancer de la prostate et à sa thérapie par ultrasons focalisés". Lyon, INSA, 2004. http://theses.insa-lyon.fr/publication/2004ISAL0018/these.pdf.
Pełny tekst źródłaAn ultrasonic imaging device for prostate elastography was developed. A balloon filled with a coupling liquid served as a compressor. In vitro, the system was capable of imaging the anatomy of the prostate as well as benign and malignant tumors. Then the major influence of the acquisition frame on the image quality in vivo was demonstrated. The system was shown to be able to detect prostate cancer and to visualize the effects of high intensity focused ultrasound (HIFU) therapy in vivo. It was finally shown in vitro that the formation of an elementary HIFU lesion could be observed by passive elastography, using only temperature elevation to create the elastogram
Al, Sabbagh Chantal. "Liposomes thermosensibles furtifs pour l'administration du 5-Fluorouracile déclenchée par ultrasons". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA114819/document.
Pełny tekst źródłaWe optimized thermosensitive liposomes encapsulating an anticancer drug, 5-Fluorouracil (5-FU), in order to trigger the release upon focused ultrasound-mediated mild hyperthermia at the tumor. This approach would improve drug efficacy and would lower side effects. Liposomes were prepared by the lipid hydration method by mixing 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) for its temperature sensitivity at 41.5 ± 0.5°C, cholesterol (CHOL) to promote liposome stability towards blood components, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG) to confer stealthiness to the formulation. The experiments confirmed that the liposomes formulated with DPPC/CHOL/DSPE-PEG in a molar ratio 90:5:5 mol% are thermosensitive, while liposomes composed of the same lipid mixture in a ratio 65:30:5 mol% were considered non thermosensitive negative control. The optimization of passive encapsulation of 5-FU yielded an encapsulation efficacy (encapsulated 5-FU/total 5-FU) of 13%. 5-FU was, however, very weakly retained (12%) in the aqueous core of liposomes following dilution due to the generation of an osmotic gradient. The retention of 5-FU has been optimized (93%) by the active encapsulation technique based on the intraliposomal complexation of 5FU with copper-polyethylenimine complex encapsulated beforehand into liposomes. This technique also improved 5-FU encapsulation efficacy by 3-fold (37%), yielding a loading efficiency (final drug/lipid ratio, mol/mol) of approximately 50%. The resulting thermosensitive liposomes and non thermosensitive liposomes have a hydrodynamic diameter and a surface charge around 65 nm and -10 mV, and 105 nm and -4.9 mV, respectively. Heat-triggered drug delivery was evaluated using focused ultrasound, and showed a release of 68% of the encapsulated 5-FU from thermosensitive liposomes, within 10 min, whereas release remained below 20% for the non thermosensitive formulation. Furthermore, the cytotoxicity of 5-FU-copper-polyethylenimine complex-loaded liposomes towards HT-29 human colorectal carcinoma cell line was evaluated. Results revealed that lipids at a concentration of 800 µM are not cytotoxic (80% viability). Moreover, 5-FU complexation has no impact on its cytotoxic activity, disclosing that liposomes toxicity arose from 5-FU and not from the excipients. Nevertheless, 5-FU-copper-polyethylenimine complex-loaded liposomes exhibited a lower half maximal inhibitory concentration of 49 µM compared to 115 µM for complex solution. This enhancement of cytotoxicity was attributed to the cellular internalization of liposomes. Pharmacokinetics in mice bearing HT-29 xenograft tumor showed that liposomes can extend the plasma distribution half-life of 5-FU by a factor 1.4. Furthermore, areas under the concentration-time curve over 24 h were higher by 1.9- and 2.9-fold when the drug was encapsulated into thermosensitive and non thermosensitive liposomes, respectively, compared to free 5-Fluorouracil. Finally, non thermosensitive liposomes significantly increased 5-FU accumulation in tumor by 2-fold, compared to 5-FU solution. In conclusion, these 5-FU-loaded thermosensitive liposomes represent valuable carriers to investigate the therapeutic efficacy following focused ultrasound-mediated heat application
Lucidarme, Olivier. "Quantification non invasive de la microcirculation par imagerie ultrasonore fonctionnelle de contraste avec les techniques de destruction reperfusion". Paris 12, 2003. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002118320204611&vid=upec.
Pełny tekst źródłaOur aim was to study the potential for quantitative contrast enhanced functional ultrasound imaging (fUSI) to assess microcirculation. We described in vitro and in vivo the "entrance in the section phenomenon" that introduces a distortion of the refilling curves when the vessels that feed the region or interest have previouslv traveled across the ultrasound tield. We validated in vitro a b model based on the destruction phase of microhuhbles during ultrasound emission. This model allows the estimation of quantitative flow data during acquisitions of only 1 or 2 seconds. We finally studied a non tumor angiogenesis model in 36 mice. Ultrasound measurement (during the destruction phase) ot' the Uractional blood volume in a gel impregnated with growth exhihited a higher correlation vith the fractional vascularized area of gel than with the microvascular density. Microbubble velocity assessed on fUSI did not change as mi crocirculation increased
Lucidarme, Olivier Berger Geneviève. "Quantification non invasive de la microcirculation par imagerie ultrasonore fonctionnelle de contraste avec les techniques de destruction reperfusion". Créteil : Université de Paris-Val-de-Marne, 2003. http://doxa.scd.univ-paris12.fr:80/theses/th0211832.pdf.
Pełny tekst źródłaRouviere, Olivier. "Apport de l'imagerie au traitement du cancer de prostate par ultrasons focalises de haute intensité". Lyon 1, 2003. http://www.theses.fr/2003LYO10121.
Pełny tekst źródłaBaranger, Jérôme. "Applications de l’imagerie ultrarapide par ultrasons à l’étude de phénomènes transitoires vasculaires et neuronaux". Thesis, Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2019SORUS571.pdf.
Pełny tekst źródłaThis thesis focuses on the application of ultrafast ultrasound imaging to the detection of transient vascular and neuronal phenomena. First, efforts have been made to improve the detection of blood flow with ultrafast Doppler, by automating a filter between tissue and blood signals, based on singular value decomposition (SVD). The concept of spatial similarity matrix has been introduced in order to adaptively optimize the SVD filter parameters. Second, the study of cerebral blood flow fluctuations, the foundation of functional ultrasound imaging (fUS), has been applied to human neonates. This involved the realization of a system to fix an ultrasound probe on the head of an infant. The acquisition of plane-by-plane ultrasound volumes allows the spatial registration of a cerebral atlas of the newborn. This delineates brain areas in fUS acquisitions. The study of spontaneous oscillations of cerebral blood volume within these zones and their levels of mutual correlations reveals the functional connectivity. Dynamic analysis revealed abnormal networks in a pathological patient. Finally, it could be shown that the cortical areas were the most involved in inter-hemispheric connectivity. Third, ultrafast imaging has been applied to a mystery of physiology: Korotkoff sounds used for blood pressure. It has been shown that these noises are caused by the passage of the pulse wave, amplified and deformed by the sphygmomanometer cuff
Larrat, Benoît. "Méthodes de quantification des déplacements en Imagerie par Résonance Magnétique et leurs applications pour la caractérisation mécanique des tissus mous et le guidage de la thérapie par ultrasons focalisés". Phd thesis, Paris 7, 2010. http://www.theses.fr/2010PA077030.
Pełny tekst źródłaPathologies often affect tissue stiffness. Recent techniques enable to measure elasticity non invasively via ultrasound and MRI. They have shown a strong potential for medical diagnosis. The first chapter of this thesis introduces those techniques. The accuracy of the inversion algorithms used to retrieve viscoelastic properties from experimental data is discussed for the so called "Supersonic Shear Imaging" (SSI) and "Magnetic Resonance Elastography" (MRE) techniques. In the second chapter, MR-elastography is done at high magnetic field for the study of different pathologies in rodent models: steatohepatitis, Alzheime disease, plaque sclerosis. Significant correlations are found between complex shear modulus values and histological investigations. The third chapter studies the link between the composition and the structure of soft tissues on the one hand and their macroscopic viscoelastic properties on the other hand. Dispersion curves of the elastic moduli are acquired in vivo (breast, brain) and in vitro (composite gels) with the SSI and MRE techniques. Chapter four introduces a new adaptive focusing technique. Phase aberrations distort ultrasound beams propagating through heterogeneous medium. These phase aberrations are corrected via a procedure aimed at maximizing the acoustic energy at the focus. An experimental demonstration of this technique is done in vitro. The last chapter presents a complete MRI protocol for the monitoring of transcranial focused ultrasound before, meanwhile and after the therapy. This protocol is successfully validated in vivo in rats with and without implanted tumors
Lourenco, de Oliveira Philippe. "Conception de solutions technologiques et d’outils pour le traitement d’organes par ultrasons focalisés guidés par IRM". Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13963/document.
Pełny tekst źródłaTreatment with Focused Ultrasound (HIFU) combined with Magnetic Resonance Imaging (MRI) control is a promising method for xxx thermotherapy on patient free breathing. A technological solution for improving the transfer of electrical power to the ultrasonic transducer around a adjustable impedance matching system has been achieved. A chapter was devoted to the characterization of transducers acoustic field by measure and simulation. The last two chapters concern the development of software tools around the MRI. A method to determinate the thermal parameters of tissues heated, useful to compute an optimal temperature control was developed. Finally, a feasibility study has been conducted on the combination of fast ultrasound motion estimation with robust MRI motion estimation, this to improve the quality of the motion tracking
Blaize, Kevin. "Cartographier le traitement de l'information visuelle cérébrale grâce aux ultrasons fonctionnels". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS114.
Pełny tekst źródłaIn the brain, the visual system includes the Lateral Geniculate Nucleus, the Superior Colliculus and the visual cortex. These structures have been studied since the 50’s and these studies have relied on functional MRI but also on the development of functional surface microscopic imaging techniques. To examine the spatiotemporal resolution of the ultrafast ultrasound imaging technique, we measured visual responses in in the cerebral structures on anesthetized rats in one imaging plan or with a 3D reconstruction. After having validated our technology on rodents, we have applied the technique to awake non-human primate visual cortex. We reconstructed the retinotopic maps of visual cortex, at the surface and in depth. In addition, we could resolve the ocular dominance columns within V1, which represent a major functional structuration in the primary visual cortex. This functional observation suggests the presence of ocular dominance beyond layer 4 in layers 3 and 5 of V1. In conclusion, this thesis work has demonstrated that the functional ultrafast ultrasound imaging can measure activity in the visual system for both rats and non-human primates, anesthetized and awake. This new imaging technique can provide functional measures with a high spatiotemporal resolution in the deep tissue. This illustration on the visual system highlights the potential of the technique to measure functional units not accessible to optical surface analysis and below the resolution of fMRI. Future studies will have to define if this technique can still provide a better resolution than fMRI in deeper structures than 1cm
Li, Xiang. "Nano-émulsions radio-opaques iodées pour applications précliniques en imagerie par rayons X". Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAF041/document.
Pełny tekst źródłaThe X-ray microtomography (called mico-CT, CT = Computed Tomography) is a high-resolution X-ray tomography, uses X-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model. The contrast agent is a substance used to enhance the contrast of structures or fluids within the body in medical imaging. The purposes of the thesis were the development of iodine-containing nano-emulsion based contrast for preclinical applications in biomedical imaging. We proposed to study blood pool contrast agents based on iodine-containing nano-emulsions and to develop simpler procedure for the preparation of these iodine-containing nano-emulsions. Three different iodinated oils were synthesized and used as the contrasting part in the nano-emulsions. Finally, nano-emulsions of iodinated α-tocopherol have been enabled us to achieve the purpose of the thesis. These iodinated nano-emulsions demonstrated very good biocompatibility and showed prolonged and significant contrast enhancement in both bloodstream and liver tissues
Follet, Hélène. "Caractérisation biomécanique et modélisation 3D par imagerie X et IRM haute résolution de l'os spongieux humain : évaluation du risque fracturaire". Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0105/these.pdf.
Pełny tekst źródłaTo prevent bone pathology, the aim of this study is to test a new methodology to evaluate fracture risk of human calcaneus cancellous bone. By using i) clinical data (bone mineral density, microstructure, DXA, Scanner X, Histomorphometry) and ii) high definition imaging techniques (RMN at 78 µm and µComputed Tomography at 10µm), it will be possible to estimate cancellous bone mechanical properties (Young Modulus and compressive maximal stress). Two tests have been implemented : a compressive test on a cubic sample of cancellous bone, and secondly, a bending test on trabecular bone. Different finite element models of these have been used and allow to determine mechanical properties of trabecular bone. Fracture risk can be evaluated by damage quantification and tissue strain level. Results of this methodology will then be compared with those obtained by classical clinical techniques
Follet, Hélène Rumelhart Claude. "Caractérisation biomécanique et modélisation 3D par imagerie X et IRM haute résolution de l'os spongieux humain évaluation du risque fracturaire /". Villeurbanne : Doc'INSA, 2006. http://docinsa.insa-lyon.fr/these/pont.php?id=follet.
Pełny tekst źródłaMadelin, Guillaume. "Développements méthodologiques de l'IRM à bas champ : élastographie, interaction IRM-Ultasons et polarisation dynamique nucléaire". Bordeaux 2, 2005. http://www.theses.fr/2005BOR21253.
Pełny tekst źródłaThis thesis deals with low field (0. 2 T) Magnetic Resonance Imaging (MRI). Magnetic Resonance Elastography allows to assess some viscoelastic properties of tissues by imaging of acoustic strain waves. In the next part, an ultrasonic transducer was calibrated using the comparison of the balance method and laser interferometry. Then, it was tried to modify the T1 contrast of tissues by spin-phonon interaction due to the application of ultrasound at the Larmor frequency. No modification was obtained, but an acoustic streaming was observed. The visualization of this streaming makes possible to calibrate transducers and to assess some properties of liquids. The last part was dedicated to set up Dynamic Nuclear Polarization experiments, based on the polarization transfer of unpaired electrons of free radicals to the protons of water. An enhancement of the NMR signal by a factor 30 was obtained on nitroxides
Ostiguy, Pierre-Claude. "Effet de la composition des matériaux composites sur la caractérisation et détection par ondes de Lamb". Mémoire, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/5524.
Pełny tekst źródłaKwiecinski, Wojciech. "Ultrasound cardiac therapy guided by elastography and ultrafast imaging". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066131/document.
Pełny tekst źródłaAtrial fibrillation (AF) affects 2-3% of the European and North-American population, whereas ventricular tachyarrhythmia (VT) is related to an important risk of sudden death. AF and VT originate from dysfunctional electrical activity in cardiac tissues. Minimally-invasive approaches such as Radio-Frequency Catheter Ablation (RFCA) have revolutionized the treatment of these diseases; however the success rate of RFCA is currently limited by the lack of monitoring techniques to precisely control the extent of thermally ablated tissue.The aim of this thesis is to propose novel ultrasound-based approaches for minimally invasive cardiac ablation under guidance of ultrasound imaging. For this, first, we validated the accuracy and clinical viability of Shear-Wave Elastography (SWE) as a real-time quantitative imaging modality for thermal ablation monitoring in vivo. Second we implemented SWE on an intracardiac transducer and validated the feasibility of evaluating thermal ablation in vitro and in vivo on beating hearts of a large animal model. Third, a dual-mode intracardiac transducer was developed to perform both ultrasound therapy and imaging with the same elements, on the same device. SWE-controlled High-Intensity-Focused-Ultrasound thermal lesions were successfully performed in vivo in the atria and the ventricles of a large animal model. At last, SWE was implemented on a transesophageal ultrasound imaging and therapy device and the feasibility of transesophageal approach was demonstrated in vitro and in vivo. These novel approaches may lead to new clinical devices for a safer and controlled treatment of a wide variety of cardiac arrhythmias and diseases
Salomir, Rares. "Local hyperthermia by MRI-guided focused ultrasound : fast MR-thermometry and on-line temperature control : feasibility studies of tumor thermal ablation". Bordeaux 1, 2001. http://www.theses.fr/2001BOR12418.
Pełny tekst źródłaKerbrat, Estelle. "Imagerie par retournement temporel en contrôle non destructif des matériaux". Paris 7, 2001. http://www.theses.fr/2001PA077207.
Pełny tekst źródłaSmagin, Nicolay. "Caractérisation des écoulements liquides par méthode de conjugaison de phase paramétrique des ondes ultrasonores". Ecole centrale de Lille, 2008. http://tel.archives-ouvertes.fr/docs/00/75/64/62/PDF/These_N_Smagin.pdf.
Pełny tekst źródłaThe object of this work is the investigation of parametrically phase conjugate waves propagation in moving media and the demonstration of their possible applications for liquid flow velocimetry. The investigation of nonlinear effects accompanying the propagation and interaction of phase conjugate waves in moving media such as higher harmonics generation and Brillouin scattering is made. A possibility of application of these effects for precision improvement of conventional acoustic systems of flow velocimetry is considered. It is shown that the phase synchronization principle for cascade generation of higher harmonics is still valid in moving media which allows to improve the sensitivity of measurement proportionally to the number of used harmonic. It is also shown that the phase shift of Stokes component of differential frequency generated in moving media by Brillouin scattering of phase conjugate wave with the reference one corresponds to the one of the phase conjugate wave. The effects of higher harmonics generation and Brillouin scattering can be used simultaneously to improve the sensitivity and precision of liquid flow velocity measurements. The possible applications of wave phase conjugation effect to liquid flows velocimetry are presented. A method of simultaneous measurement of mixture relative concentrations and flow velocity is elaborated
Laloy-Borgna, Gabrielle. "Micro-élastographie : caractérisation mécanique de la cellule par ondes élastiques". Electronic Thesis or Diss., Lyon 1, 2023. http://www.theses.fr/2023LYO10058.
Pełny tekst źródłaDyanmic elastography is an imaging method to measure the elasticity of biological tissues in a non-invasive and quantitative way. Recently, the transposition of the technique to a small scale has been called dynamic micro-elastography and has allowed the first measurements of cellular elasticity by shear waves using an optical microscope. This thesis aims to undetstand the limits of this technique and to develop new micro-elastography methods, to test new wave sources but also potential applications of the technique. In a first step, the dispersion of shear waves was studied on gelatin phantoms. Two distinct regimes of guided elastic waves and shear waves were identified. The high-frequency limit of wave propagation was also explored, establishing the existence of a cutoff frequency which explains the absence of ultrasonic shear imaging. The same approach was then applied to visco-elastic fluids, revealing two cutoff frequencies and revisiting previous studies on rheology and wave propagation in this type of medium. Then, the initial objective being to carry out micro-elastography on single cells and the experiments previously carried out with micro-pipettes presenting certain defects, an original method of cellular micro-elastography was developed. An oscillating microbubble is used as a contactless shear wave source at 15 kHz to perform experiments on blood cells whose diameter is about 15 µm. These are the smallest objects ever explored by elastography. Larger objects, cell clusters of a few tens of thousands of cells have also been studied. Indeed, since ultrasound elastography of these tumour models of about 800 µm in diameter is impossible, optical micro-elastography is a suitable technique. These samples contain magnetic nanoparticles, so a magnetic pulse could be used as a wave source. Previously, proofs of concept on both macroscopic (in ultrasonic elastography) and microscopic (in optical micro-elastography) phantoms were conducted to validate the use of this diffuse field source. Finally, pulse wave measurements were performed on retinal arteries of about 50 µm in diameter using laser Doppler holography acquisitions performed in vivo. The application of monochromatic correlation algorithms allowed the measurement of guided wave velocities, finally revealing the existence of a second pulse wave, an antisymmetric bending wave. This guided wave, much slower than the axisymmetric pulse wave studied so far, was also observed on the carotid artery thanks to ultrafast ultrasound acquisitions
Jeanjean, Pauline. "Thermothérapies guidées par imagerie pour le traitement des cancers". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0396.
Pełny tekst źródłaThis present work demonstrates that thermal ablation and mild hyperthermia could be combined for solid tumor treatment. Proof of concept was established by molecular imaging in cell culture in vitro and using mouse models in vivo.Cancer cell viability in culture and in the tumor was followed by bioluminescence imaging using luciferases constitutive expression. Imaging reporter genes were also coupled with thermo-induced promoter to visualize mild hyperthermia areas in mice. The temperature rise was achieved using non-invasive techniques such as magnetic hyperthermia and MR-guided focused ultrasounds. Magnetic hyperthermia was performed using iron oxide magnetic nanoparticles placed in an alternative magnetic field to induce an increase of temperature monitored by infrared imaging. Magnetic nanoparticles distribution was followed by photonic and electronic microscopy, flow cytometry and fluorescence imaging. Focused ultrasounds have also been used for tumor heating. Temperature changes were followed by MR and temperature used to control in real time the ultrasonic power. These in vivo experimental approaches demonstrated that central tumor thermal ablation could be combined with peripheric mild hyperthermia of tumor microenvironment.As magnetic hyperthermia and MR-guided focused ultrasounds are currently in clinic, our results reveal new opportunities for cancer therapies combining thermal ablation with innovative strategies based on controlled drug release from thermo-sensitive nanoparticles or thermo-induced therapeutic gene expression
Thebault, Caroline. "Liposomes théranostiques pour le ciblage magnétique et le relargage d'un antitumoral par ultrasons focalisés, suivis par IRM multiparamétrique". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066022.
Pełny tekst źródłaTheranostic systems with imaging and therapeutic properties are developed to monitor treatments in vivo. The strategy we propose here is to design thermosensitive drug-loaded magnetic liposomes to treat superficial colon tumors CT26 on mice. These nanocarriers can be accumulated in the tumor by using a magnetic field gradient and the drug release can be triggered by a local heating induced by HIFU (High Intensity Focused Ultrasounds). They have been developed by co-encapsulation of magnetic nanoparticles and the antitumoral drug CA4P (Combretastatin A-4 Phosphate) in thermosensitive liposomes. The high loading of maghemite (γ-Fe2O3) magnetic nanoparticles enables both magnetic targeting and in vivo monitoring by MRI of this Ultra-Magnetic Liposomes (UML). In vitro HIFU heating at the UML membrane transition temperature improved the drug release. In vivo UML biodistribution was evaluated with dynamic susceptibility contrast imaging adjusted in time acquisition in MRI and the magnetic targeting efficiency was shown with a new MRI imaging processing. Adjustments of in vivo HIFU sequences to locally heat the tumor at the UML transition temperature allowed the triggering of drug release. Treatment efficiency was monitored by multiparametric diffusion, T2* weighted, anatomical and perfusion MRI and histology
Zemzemi, Chadi. "Élastographie par retournement temporel : mesure des propriétés mécaniques des tissus biologiques par réseau de sources d’onde de cisaillement". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1217/document.
Pełny tekst źródłaThis thesis is in line with shear-wave elastography research. After, a bibliographic review, an experimental study shows that the resolution on ultrasound elastography is of the same order of magnitude of the echography resolution and its limit exceeds the shear-wavelength. The original aspect of this work is the use of a phased array of mechanical sources to generate and control shear waves. A time reversal mirror of six shakers is set up. This device shows a space-time control of shear-wave field in gelatin-graphite phantom. Compared to the use of a single source, this phased array of shear-wave improves by 10dB the signal to noise ratio. Using this method on human skull model shows the possibility to deliver and control shear waves in brain using bone conduction. Finally, the application of this method on shear-wave elastography of abdominal layers is shown by a study on synthetic model and in vivo on a healthy volunteer
Mora, Cofré Marco Ayache Alain. "Ensemble de niveaux robustes au speckle et recalage B-spline application à la segmentation et l'analyse du mouvement cardiaque par des images ultrasons /". Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000658.
Pełny tekst źródłaBour, Pierre. "Non-invasive treatment of cardiac arrhythmias by high-intensity focussed ultrasound guided by magnetic resonance imaging". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0731/document.
Pełny tekst źródłaHigh intensity focused ultrasound has the ability to deposit ultrasonic energy locally and non-invasively into biological tissues. It is possible to exploit the mechanical and/or thermal effects according to the ultrasonic parameters used. Guided by a Magnetic Resonance Imaging (MRI) scanner, this technology is equipped with a planning modality and real-time monitoring of the procedure. As of now, applications of MRI-guided focused ultrasound are on fixed organs, including brain and bone or uterine fibroid. For the heart, the presence of cardiac and respiratory movements constitutes an important difficulty, both for the ultrasonic (ballistic) treatment and for the temperature monitoring under MRI (artefacts on images). In addition, the rib cage acts as a barrier for the propagation of ultrasounds. In this thesis work, a set of new technological development have been developed for ablation and non-invasive cardiac stimulation using focused MRI-guided ultrasound. A first study shows the technical feasibility of controlling heart rhythm by short ultrasound pulses targeted to the myocardium. The influence of the parameters of the pulses (duration, amplitude, emission time in the cardiac cycle) were studied quantitatively on isolated beating heart then in vivo on a preclinical model. For this, an original device was developed. A second study presents new rapid MRI methods for simultaneously mapping the temperature and local displacement induced by focused ultrasound. The method is validated on the liver on a preclinical model and demonstrates that it is possible to correlate the thermal dose obtained by MR-thermometry with a change in the mechanical properties of the treated tissues measured simultaneously. A third study consisted in developing a technique for measuring the position of the target in 3D real-time using some elements of the ultrasonic transmitter as receivers. This measure allows to dynamically correct the position of the ultrasonic focus to maximize energy deposition at the targeted point. In addition, we monitored in real-time the procedure using MR-thermometry at a rate of 10 images per second. Here again a preclinical validation is presented. This thesis work proposes important advances to remove the current locks of the technology allowing to envision noninvasive treatments of cardiac pathologies, all guided by MRI in real-time
Touma, Rita. "Approche matricielle de l’imagerie sismique passive par ondes de volume". Thesis, Université Grenoble Alpes, 2022. http://www.theses.fr/2022GRALU011.
Pełny tekst źródłaRevealing the structure of fault zones provides insights required to assess seismic hazards. Reflection imaging methods, in particular migration, are commonly used to image the subsurface. An accurate velocity model is often needed to properly locate the reflectors in depth.Imaging fault zones is challenging due to the complex distribution of velocity. Also, most reflection techniques image fault zones indirectly from the discontinuity of geological layers. Wave diffraction by small-scale heterogeneities, such as cracks and fractures is generally neglected.In this thesis, we propose a matrix imaging approach for geophysical exploration that handles the velocity variation in the crust and allows to resolve heterogeneities of the order of the wavelength throughout the fault zone.The reflection matrix approach is inspired from previous studies in ultrasound and optical imaging of complex media. First, ambient noise cross-correlations are used to retrieve the reflection matrix associated with a dense array of geophones. The body wave components of this matrix contains all the information available on the medium. Second, the presented approach does not require a detailed velocity model of the subsurface. A set of matrix operation is applied to compensate for the mismatch between the actual wave velocity model and its approximate model.In a first application, we use ambient noise records in the frequency band [10 20] Hz from a dense array in order image the San Jacinto Fault, California, at small scale with an horizontal resolution of 80 m. ZZ cross-correlations are computed and arranged as 2D matrix. By applying time delays, the response matrix is projected to depth, using a homogeneous velocity model. A focused reflection matrix is obtained, that contains the impulse response between virtual sources and receivers at depth. From this matrix, the image of the medium is built and the resolution of the image can be quantified.Variations between the considered model and the reality result in phase distortions, i.e aberrations, that have detrimental effects on the image of the medium.We develop an aberration correction process that allows to compensate for these distortions by introducing a novel operator, the distortion matrix. 3D images of the first 4 km of the crust are retrieved. These images reveal the backscattered intensity generated by the heterogeneities in the medium. The location and reflectivity of scatterers are retrieved with a resolution 8 times better than the one in free space. Differences in the scattering between the Northwest and the Southeast of the fault were reported with an intense localized damage zone in the Southeast.In a second application, we image the large scale structure of North Anatolian Fault using [0.1 0.5] Hz horizontal cross-correlations computed between 73 pairs of stations. A multi-layered velocity model is considered. A local correction of the phase distortions is performed. The scattering structure of the crust and the upper mantle is revealed. Differences in the Moho depth are reported, with a step below the northern branch. Strong scattering is observed in the region lying along the northern strand of the fault, coinciding with the limit of the lithospheric blocks. The scattering in the North extends to 60 km depth, suggesting a shear zone that penetrates in the upper mantle beneath the northern strand. The scattering also reveals the deep structure of the main geological blocks.In the last part of this thesis, we propose an approach that paves the route towards a 3D passive tomography of the body wave velocity. Finally, all the presented applications confirm the efficiency of the reflection matrix approach in revealing the structure of the subsurface. It provides new insights into the scattering distribution in the Earth. It can be applied to any scale, scattering regime, and frequency bandwith, if the spatial sampling of the geophones' array satisfies the Nyquist criterion
Ait, Ali Lahcen. "Etude théorique et expérimentale des non linéarites ultrasonores : intérêt du second harmonique en imagerie par réflexion". Nancy 1, 2001. http://www.theses.fr/2001NAN10010.
Pełny tekst źródłaMagnin, Rémi. "Développements précliniques de nouveaux outils utilisant les ultrasons transcraniens guidés par IRM haut champ pour la délivrance de médicaments dans le cerveau et la stimulation non invasive de circuits neuronaux". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS037/document.
Pełny tekst źródłaBy preventing most of the molecules from penetrating the brain in sufficient quantitiy, the Blood Brain Barrier represents a major obstacle for the development of new therapeutic drugs for brain diseases. A new technique introduced in the early 2000’s combining focused ultrasound and circulating microbubbles has however shown promising results, allowing to induce a local and transient permeabilization of the BBB in a non-invasive manner, thus significantly improving the amount of drugs delivered to the Central Nervous System (CNS). However, this protocol may present some risks (oedema, small hemorrages) which can be avoided by a good control of the acoustic beam properties. To do so, Magnetic Resonance Imaging (MRI) represents a very useful tool since it allows planning, monitoring and following the permeabilization effects by using MRI contrast agents and quantitative imaging sequences (T1/T2 relaxometry). During this PhD, we worked on developing new tools for the study of ultrasound induced BBB permeabilization in rodents. The first part of this work consisted in developing a MR compatible motorized device, allowing the displacment of the ultrasound transducer within a 7T preclinic MRI scanner, with a realtime feedback on the acoustic beam position thanks to MR Acoustic Radiation Force Imaging (MR-ARFI). We have shown that this system allowed performing a full BBB permeabilization protocol under MR-guidance, with an accurate and reproducible choice of the targeted anatomical structure. This system was also used to deliver drugs along arbitrary trajectories over extended regions of the brain. Another part of the work was dedicated to study and improve the safety of the procedure. The influence of different acoustic parameters (acoustic pressure, duty cycle) on the permeabilization efficacy was studied, as well as histologic investigations of short and mid-term effects of BBB permeabilization for different acoustic pressures on healthy rats. Finally, we investigated the diffusion process of contrast agents within the brain tissues following BBB permeabilization. We have shown that this technique allowed accurate measurements of brain tissues tortuosity in a non-invasive way, and found that the tortuosity was not modified by the ultrasound application
Chadebecq, François. "Estimation de l'échelle absolue par vision passive monofocale et application à la mesure 3D de néoplasies en imagerie coloscopique". Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22612/document.
Pełny tekst źródłaVision-based metrology devices generally embed stereoscopic sensors or active measurement systems. Most of the passive 3D reconstruction techniques (Structure-from-Motion, Shape from-Shading) adapted to monocular vision suffer from scale ambiguity. Because the processing of image acquisition implies the loss of the depth information, there is an ambiguous relationship between the depth of a scene and the size of an imaged object. This study deals with the estimation of the absolute scale of a scene using passive monofocal vision. Monofocal vision describes monocular system for which optical parameters are fixed. Such optical systems are notably embedded within endoscopic systems used in colonoscopy. This minimally invasive technique allows endoscopists to explore the colon cavity and remove neoplasias (abnormal growths of tissue). Their size is an essential diagnostic criterion for estimating their rate of malignancy. However, it is difficult to estimate and erroneous visual estimations lead to neoplasias surveillance intervals being inappropriately assigned. The need to design a neoplasia measurement system is the core motivation for our study. In the first part of this manuscript, we review state-of-the-art vision-based metrology devices to provide context for our system. We then introduce monofocal optical systems and the specific image formation model used in our study. The second part deals with the main contribution of our work. We first review in detail state of the art DfD (Depth-from-Defocus) and DfF (Depth-from-Defocus) approaches. They are passive computer vision techniques that enable us to resolve scale ambiguity. Our core contribution is introduced in the following chapter. We define the Infocus-Breakpoint (IB) that allows us to resolve scale from a regular video. The IB is the lower limit of the optical system’s depth of field. Our system relies on two novel technical modules: Blur-Estimating Tracking (BET) and Blur-Model Fitting (BMF). BET allows us to simultaneously track an area of interest and estimate the optical blur information. BMF allows us to robustly extract the IB by fitting an optical blur model to the blur measurement estimated by the BET module. For the optical system is monofocal, the IB corresponds to a reference depth that can be calibrated. In the last chapter, we evaluate our method and propose a neoplasia measurement system adapted to the constraints in colonoscopy examination. The last part of this manuscript is dedicated to a prospect of extension of our method by a generative approach. We present, as a preliminary study, a new NRSfM (Non-Rigid Structure-from-Motion) method allowing the scaled Euclidean 3D reconstruction of deformable surfaces. This approach is based on the simultaneous estimation of dense depth maps corresponding to a set of deformations as well as the in-focus color map of the flattened surface. We first review state-of-the-art methods for 3D reconstruction of deformable surfaces. We then introduce our new generative model as well as an alternation method allowing us to infer it
Marquet, Fabrice. "Méthodes échographiques de correction et de suivi des traitements thérapeutiques par ultrasons focalisés de forte intensité". Phd thesis, Université Paris-Diderot - Paris VII, 2009. http://pastel.archives-ouvertes.fr/pastel-00579176.
Pełny tekst źródłaGahagnon, Solène. "Etude in vivo du comportement mécanique du derme par une méthode élastographique haute résolution : applications à l'exploration d'anomalies du tissu élastique (syndrome de Marfan)". Thesis, Tours, 2009. http://www.theses.fr/2009TOUR3116/document.
Pełny tekst źródłaBessière, Francis. "Amélioration des techniques d’ablation pour le traitement des arythmies cardiaques : nouvelles modalités diagnostiques et thérapeutiques par ultrasons". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1225/document.
Pełny tekst źródłaAt the crossroads of medicine and physics, this work aimed to provide innovative diagnostic and therapeutic tools based on ultrasound, in the field of cardiac electrophysiology. A system capable of delivering HIFU into the heart by a transesophageal route using ultrasound (US) imaging guidance was developed and tested in vivo in six male pigs. HIFU exposures were performed on atria and ventricles. At the time of autopsy, visual inspection identified thermal lesions in the targeted areas in three of the animals. These lesions were confirmed by histologic analysis (mean size: 5.5 mm2 x 11mm2). No esophageal thermal injury was observed. One animal presented with bradycardia due to an atrio-ventricular block, which provides real-time confirmation of an interaction between HIFU and the electrical circuits of the heart. There was still a lack of accuracy, mainly related to cardiac motion, and to anatomical structures in between the targets and the transducer. It was mainly related to the in vivo model and its anatomy, far from the human’s. The search for a better model led to conclusive imaging tests on baboons. Additional experiments were conduced in order to improve the mapping of ventricular arrhythmias and the monitoring of lesion formation during ablation. First, experiments were conducted on left ventricles of four isolated working mode swine hearts. The protocol aimed at demonstrating that different patterns of mechanical activation could be observed whether the ventricle was in sinus rhythm, paced from the epicardium, or from the endocardium. Electromechanical wave imaging (EWI) acquisitions were recorded on the anterior, lateral, and posterior segments of the left ventricle. Loop records were blindly assigned to two readers. EWI sequences interpretations were correct in 89% of cases. The overall agreement rate between the two readers was 83%. When in a paced ventricle, the origin of the wave front was focal and originating from the endocardium or the epicardium. In sinus rhythm, wave front was global and activated within the entire endocardium towards the epicardium at a speed of 1.7±0.28 m.s-1. Wave front speeds were respectively measured when the endocardium or the epicardium were paced at a speed of 1.1 ± 0.35 m.s-1 vs 1.3±0.34 m.s-1 (p=NS). Lastly, we investigated the feasibility of a dual therapy and imaging approach with the same transoesophageal device. We demonstrated on ex-vivo samples that transoesophageal shear wave imaging (SWE) can map the extent of the HIFU lesions. HIFU ablation was performed with the transoesophageal probe on ex-vivo chicken breast samples (n=3), then atrium (left, n=2) and ventricle (left n=1, right n=1) of swine heart tissues. SWE provided stiffness maps of the tissues before and after ablation. Areas of the lesions were obtained by tissue color change with gross pathology and compared to SWE. Shear modulus of the ablated zones increased from 4.8±1.1 kPa to 20.5+/-10.0 kPa (ratio 5.0±3.2) in the chicken breast, from 12.2±4.3 kPa to 30.3±10.3 (ratio 3.2±2.0) in the atria and from 21.2±3.3kPa to 73.8±13.9kPa (ratio 3.7±1.2) in the ventricles. On gross pathology, the size of the lesions ranged from 0.1 to 1.5cm2 in the imaging plane area and morphometric characteristics were fitting with elasticity-estimated depths and widths of the lesions
Bessière, Francis. "Amélioration des techniques d’ablation pour le traitement des arythmies cardiaques : nouvelles modalités diagnostiques et thérapeutiques par ultrasons". Electronic Thesis or Diss., Lyon, 2019. http://www.theses.fr/2019LYSE1225.
Pełny tekst źródłaAt the crossroads of medicine and physics, this work aimed to provide innovative diagnostic and therapeutic tools based on ultrasound, in the field of cardiac electrophysiology. A system capable of delivering HIFU into the heart by a transesophageal route using ultrasound (US) imaging guidance was developed and tested in vivo in six male pigs. HIFU exposures were performed on atria and ventricles. At the time of autopsy, visual inspection identified thermal lesions in the targeted areas in three of the animals. These lesions were confirmed by histologic analysis (mean size: 5.5 mm2 x 11mm2). No esophageal thermal injury was observed. One animal presented with bradycardia due to an atrio-ventricular block, which provides real-time confirmation of an interaction between HIFU and the electrical circuits of the heart. There was still a lack of accuracy, mainly related to cardiac motion, and to anatomical structures in between the targets and the transducer. It was mainly related to the in vivo model and its anatomy, far from the human’s. The search for a better model led to conclusive imaging tests on baboons. Additional experiments were conduced in order to improve the mapping of ventricular arrhythmias and the monitoring of lesion formation during ablation. First, experiments were conducted on left ventricles of four isolated working mode swine hearts. The protocol aimed at demonstrating that different patterns of mechanical activation could be observed whether the ventricle was in sinus rhythm, paced from the epicardium, or from the endocardium. Electromechanical wave imaging (EWI) acquisitions were recorded on the anterior, lateral, and posterior segments of the left ventricle. Loop records were blindly assigned to two readers. EWI sequences interpretations were correct in 89% of cases. The overall agreement rate between the two readers was 83%. When in a paced ventricle, the origin of the wave front was focal and originating from the endocardium or the epicardium. In sinus rhythm, wave front was global and activated within the entire endocardium towards the epicardium at a speed of 1.7±0.28 m.s-1. Wave front speeds were respectively measured when the endocardium or the epicardium were paced at a speed of 1.1 ± 0.35 m.s-1 vs 1.3±0.34 m.s-1 (p=NS). Lastly, we investigated the feasibility of a dual therapy and imaging approach with the same transoesophageal device. We demonstrated on ex-vivo samples that transoesophageal shear wave imaging (SWE) can map the extent of the HIFU lesions. HIFU ablation was performed with the transoesophageal probe on ex-vivo chicken breast samples (n=3), then atrium (left, n=2) and ventricle (left n=1, right n=1) of swine heart tissues. SWE provided stiffness maps of the tissues before and after ablation. Areas of the lesions were obtained by tissue color change with gross pathology and compared to SWE. Shear modulus of the ablated zones increased from 4.8±1.1 kPa to 20.5+/-10.0 kPa (ratio 5.0±3.2) in the chicken breast, from 12.2±4.3 kPa to 30.3±10.3 (ratio 3.2±2.0) in the atria and from 21.2±3.3kPa to 73.8±13.9kPa (ratio 3.7±1.2) in the ventricles. On gross pathology, the size of the lesions ranged from 0.1 to 1.5cm2 in the imaging plane area and morphometric characteristics were fitting with elasticity-estimated depths and widths of the lesions