Rozprawy doktorskie na temat „Imagerie par résonance magnétique – Innovation”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Imagerie par résonance magnétique – Innovation”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Deruelle, Tristan. "Magnetic Resonance Elastography : towards prostate cancer imaging and slow compression wave imaging in softtissues". Electronic Thesis or Diss., Lyon, 2022. http://www.theses.fr/2022LYSE1068.
Pełny tekst źródłaProstate cancer is the second most prevalent cancer in men worldwide. It is suspected when the PSA density is high or/and the superficial prostate feels hard during digital rectal examination. Multiparametric MRI is now recommended prior biopsy when detecting for cancer. However, image interpretation is challenging, even for specialists, and brings many false-positive. Elastography is a technique to assess tissue stiffness by inducing small vibrations. It could provide a 3D map of the stiffness of the prostate. We believe that MR elastography could complement the current multiparametric MRI. Given prostate location and consitution, wave propagation is difficult though. The current work presents the design of a non-invasive wave generation device for the prostate. Then, a new field separation algorithm is presented. This algorithm provides a better estimation of the stiffness, and the correction of artefact generated by common vibrators. Finally, this algorithm can have applications in porous media. Indeed, in poro-elastic materials, a slow compression wave propagates. We observe such a wave in an agar gel, in a foam phantom, and in vivo in human kidney graft. In addition to the classic shear wave velocity estimation, it is now possible to estimate the compression wave velocity. This is an additional piece of information that the operator can use in its diagnostic. In the future, more porous parameters could be derived
Trillaud, Hervé. "Imagerie fonctionnelle du rein par résonance magnétique". Bordeaux 2, 1996. http://www.theses.fr/1996BOR28439.
Pełny tekst źródłaVignaux, Olivier. "Imagerie tissulaire myocardique par résonance magnétique nucléaire". Paris 5, 2002. http://www.theses.fr/2002PA05CD05.
Pełny tekst źródłaMagnetic Resonance Imaging of myocardical tissue. In patients with known or suspected cardiac desease, an "all-in-one" cardiac imaging modality should theoretically include morphological and functional analysis of the heart, but also information on myocardical tissue in order to detect its infiltration by abnormal tissues or substances and to study its perfusion and viability in ischemic disease. The specific magnetic properties with changes of relaxations times (and thereby increased or decreased signal intensities) induced by some tissues such as fatty infiltration, fibrosis, edema or inflammation allow a characterization of the myocardical tissue. Magnetic Resonance (MR) imaging also offers the potential for a complete functional study of the myocardium including contractility as well as perfusion and viability using cotrasts agents (Gadolinium-DTPA). The aim of this work was to demonstrate the ability of MR imaging to non-invasively characterize myocardical tissue and to assess its function. MR capacities of imaging the myocardical tissue have been applied to myocardical ischemia and to some specific cardiomyopathies
Kuhne, Francois. "Tumeurs choroïdiennes et imagerie par résonance magnétique". Bordeaux 2, 1988. http://www.theses.fr/1988BOR25277.
Pełny tekst źródłaSerres-Cousiné, Olivier. "Imagerie par résonance magnétique de l'endométriose pelvienne". Montpellier 1, 1990. http://www.theses.fr/1990MON11003.
Pełny tekst źródłaBlondiaux, Eléonore. "Détection cellulaire en imagerie cardiaque par résonance magnétique". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112054.
Pełny tekst źródłaObjectives: Cardiac regenerative therapies have grown considerably over the past 10 years. Despite positive effects demonstrated in animals, the clinical benefits obtained in humans are still relatively modest. The objective of this work was to better understand the factors associated with implantation of stem cells through the cell detection techniques in magnetic resonance imaging (MRI) and to improve cardiac stem cell therapy in a murine model of myocardial infarction.Materials and methods: A protocol for cell detection with gradient echo T2* sequences in cardiac MRI in vivo and a method for detection of microvessels in cardiac MRI ex vivo with high resolution Susceptibility Weighted Imaging sequences (SWI) were developed and implemented for the study of vectorization of intravenously injected endothelial progenitors cells (EPC) and the integration and evaluation of the impact of mesenchymal stem cells (MSC) administered via cellularized fibrin patches. A permanent ligation of the left anterior coronary artery was performed in adult rats. The stem cells were magnetically labeled with iron oxide nanoparticles by endocytosis.Results: Cell detection imaging showed no cell implantation in the myocardium and no improvement in cardiac functional parameters after intravenous injection of EPC, despite the aid of magnetic vectorization (n = 16 rats). With a local administration of MSC via cardiac patches (n = 37 rats), the left ventricular ejection fraction (LVEF) was improved in cellularized patches groups compared to controls. Microvascular density was increased in the infarcted and peri – infarcted areas in cellularized patches groups compared to controls in immunohistochemistry and in MRI on SWI sequences. The MRI showed no migration of cells into the myocardium from the patch, as confirmed by immunohistochemistry and Perls staining. The persistence of MSCs on the epicardial surface at D21 after implantation and flow cytometry profiling of cytokines and growth factors produced by MSC argue for cell therapy effectiveness related to the secretion of paracrine factors by stem cells.Conclusion: Susceptibility imaging allows: (1) to study myocardial vessels on SWI sequences ex vivo and (2) to assess the implementation of stem cells on gradient echo sequences T2 * in vivo. These techniques have shown that cardiac patches act as a reservoir of soluble mediators which paracrinally target the angiogenesis in the treatment of heart failure in a murine model. This is in favor of a move towards “cell free” biomaterials containing only molecules of interest such as cytokines or growth factors to circumvent immunogenic and teratogenic constraints related to the use of stem cells
Wagner, Mathilde. "Carcinome hépatocellulaire : diagnostic et caractérisation par imagerie par résonance magnétique". Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC101.
Pełny tekst źródłaImaging allows HCC diagnosis without histological examination in case of typical imaging appearance (association of hypervascularization and washout). However this appearance is not sensitive for the diagnosis of early HCC. We showed the potential of functional imaging for characterization of nodules in the cirrhotic liver. In a rat model of multinodular cirrhosis, the diffusion MRI technique with oscillating gradients (OGSE), performed ex vivo, showed potential for identification of high grade dysplastic nodules and well differentiated HCC. The classic diffusion technique with pulsed gradients (PGSE) was able to separate HCC according to histological grade. The viscoelastic properties of HCC, evaluated by magnetic resonance elastrography in the same rat model and in patients, are different from those of the cirrhotic liver. The increase of loss modulus in HCC only in vivo suggests the importance of perfusion in determining mecanical properties. We have also shown that the delayed venous phase allowed superior washout detection compared to the portal venous phase in HCC explored by MRI. The inter-observer agreement was moderate. Finally, we have shown that viable tumor regions within liver tumors could be differentiated from fibrotic and necrotic regions by measuring the pure diffusion coefficient D, but not the apparent diffusion coefficient ADC, suggesting the applicability of D in tumor characterization and monitoring after treatment
Grellier, Brigitte. "Les risques potentiels de la résonance magnétique; conséquences sur l'aptitude du personnel des centres de résonance magnétique". Bordeaux 2, 1995. http://www.theses.fr/1995BOR2M166.
Pełny tekst źródłaRadecki, Guillaume. "Imagerie cellulaire par résonance magnétique rehaussée au manganèse (CelMEMRI)". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112212/document.
Pełny tekst źródłaScience has evolved since the 19th century. New tools have appeared such as optical microscopy which gives us the vision of cells and electronic microscopy which leads us into their hearts. The magnetic resonance imaging appeared in the seventies. Evolving over time, the MRI has taken us farther and farther into the secret depths of our brains. The possibility of observing the neuronal activity thanks to the functional imaging is a major evolution. This thesis will show the possibility we have to observe the activity of a single neuron without modification of its network thanks to the manganese enhanced magnetic resonance imaging technique. The study was done on the Aplysia at very high field magnet (17T). These animals are marine gastropod mollusks with a peculiarity: their neurons are of important size and can reach 1 mm in diameter. Their neurons are grouped into several ganglia. My study concerns the buccal ganglion which is the most studied ganglia in the research in electrophysiology. Before making any acquisitions, I had to conceive several microscopic coils adapted to the size of the ganglions. By reducing the size of the coils, the signal of the noise ratio increases. Then, a double coil allowing the simultaneous acquisition of two samples was built. This antenna required the construction of pre-amplifiers operating at 730 MHz. The first series of experiments helped observe the evolution of the neuronal activity according to different stimuli linked to the eating habits of the Aplysia in vivo. Thanks to the technique implemented, I shall show that, using MRI, it is possible to distinguish the activity of each neuron with respect to a stimulus. Afterwards, to continue this work, a second series of experiments was made in vitro. I studied the behavior of neurons when perfused with neural stimulators: dopamine and serotonin, both naturally present in the Aplysia. Generally, all neurons were activated but when observing them individually, I noticed some differences. Studies in electrophysiology will allow us to get a better understanding and a confirmation of the results of this study. The MEMRI technique can be used in the future to study various disorders such as compulsive behaviors, which are present in the Aplysia, and probably have the same origins as in humans, given that many fundamental processes (such as memory studied by Eric Kandel who he demonstrated that human and Aplysia memories works with the same mechanism) are similar between the two species
Méthot, Vincent. "Imagerie par résonance magnétique fonctionnelle du rat à 7T". Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8854.
Pełny tekst źródłaSilencieux, Fanny. "Hydrogels paramagnétiques pour applications en imagerie par résonance magnétique". Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27617.
Pełny tekst źródłaHydrogels are polymers increasingly used in the field of biomaterials. Due to their low density difference with the surrounding middle, they are very difficult to visualize with magnetic resonance imaging (MRI). Contrasts agents are widely used in MRI to differentiate the different biological tissues during the imaging. The main objective of this project was the development of a paramagnetic contrast agent trapped in biocompatible hydrogels enabling their visualization in MRI. Mesoporous silica nanoparticles (MSN) were synthesized and functionalized with a clinically approved contrast agent, DTPA-Gd (gadolinium-diethylenetriamine pentaacetic acid). The nanoparticles were characterized and their relaxometric properties were evaluated. The r2/r1 relaxometric ratio of 1.46 revealed an efficient “positive” MRI contrast agent. Then, different entrapment strategies were performed in biocompatible polymers forming hydrogels: in a poly (ethylene glycol) (PEG) hydrogel (by stirring) or in an alginate hydrogel (by emulsion). These products were designed for applications in interventional surgery for biopsy needles and in microemulsion for type 1 diabetes treatment, respectively. The relaxometric performances of the PEG hydrogel were assessed by NMRD (Nuclear Magnetic Relaxation Dispersion) at different magnetic field strengths. Then, the paramagnetic hydrogel was coated on titanium substrates as substitute of biopsy needles. The substrates were cleaned and functionalized with phosphate acrylate prior to dip-coating. With a thickening agent in the suspension, PEG hydrogels of 40 to 70 µm were deposited on titanium tubes. These samples showed bright outline in MRI. A signal enhancement of 178 %, in regard with water, was obtained with gradient echo sequences shorter than 3 min. For the alginate hydrogels, beads with contrast agent showed a contrast 113 % enhanced, compared to beads without contrast agents, with a spin echo sequence of 4 min. MRI monitoring over months was done to confirm the persistence of the nanoparticles entrapment in both the PEG and alginate hydrogels. These results settled the possibility to use these hydrogels in the long term with no signal decrease, which is essential for in vivo processes. This work introduced paramagnetic hydrogels with a high contrast enhancement in MRI due to the entrapment of mesoporous silica nanoparticles functionalized with a contrast agent. Results confirmed the efficiency of the MSN-DTPA-Gd trapped in the hydrogels to visualize them in MRI. This work could lead to a long term visualization of hydrogels after implantation in the body.
Chanet, Nicolas. "Imagerie par résonance magnétique à champ cyclé in vivo". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS574/document.
Pełny tekst źródłaFast Field Cycling Magnetic Resonance Imaging (FFC-MRI) has the ability to separate two key processes that both depends on the main field intensity B0. On one hand, signal acquisition and localization and on the other hand NMR relaxation, basis of MRI contrast. The equipment thus combines a standard MR scanner with a secondary system to rapidly switch the magnetic field B0 as compared to relaxation times. FFC enables to measure the evolution of NMR relaxation as a function of magnetic field B0, namely the NMR dispersion (NMRD) profile. Combining it with MRI the NMRD profile can be localized in vivo, together with the usual characterization at fixed B0. The NMRD profile of water carries information on molecular mobility in the surrounding biological tissues, and is thus another source of contrast. The objective of this PhD project was to further develop and evaluate the potential of FFC-MRI between 1 T and 2 T in a cancer model. This work required original instrumental and methodological developments to integrate FFC in MRI. First a precise measurement of magnetic field time profile was developed, as well as the compensation of eddy currents and of irreproducible transients in the secondary system. Moreover acquisition sequences with better signal to noise efficiency and applicable for longitudinal as well as transverse relaxation were implemented. Finally a kidney tumor mouse model was explored with FFC MRI
Jaouen, Tristan. "Caractérisation du cancer de la prostate de haut grade à l’IRM multiparamétrique à l’aide d’un système de diagnostic assisté par ordinateur basé sur la radiomique et utilisé comme lecteur autonome ou comme second lecteur". Electronic Thesis or Diss., Lyon, 2022. http://www.theses.fr/2022LYSE1140.
Pełny tekst źródłaWe developed a region of interest-based (ROIs) computer-aided diagnosis system (CAD) to characterize International Society of Urological Pathology grade (ISUP) ≥2 prostate cancers at multiparametric MRI (mp-MRI). Image parameters from two multi-vendor datasets of 265 pre-prostatectomy and 112 pre-biopsy MRIs were combined using logistic regression. The best models used the ADC 2nd percentile (ADC2) and normalized wash-in rate (WI) in the peripheral zone (PZ) and the ADC 25th percentile (ADC25) in the transition zone (TZ). They were combined in the CAD system. The CAD was retrospectively assessed on two multi-vendor datasets containing respectively 158 and 105 pre-biopsy MRIs from our institution (internal test dataset) and another institution (external test dataset). Two radiologists independently outlined lesions targeted at biopsy. The Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) score prospectively assigned at biopsy and the CAD score were compared to biopsy findings. At patient level, the areas under the Receiver Operating Characteristic curve (AUC) of the PI-RADSv2 score were 82% (95% CI: 74-87) and 85% (95% CI: 79-91) in the internal and external test datasets respectively. For both radiologists, the CAD score had similar AUC results in the internal (82%, 95% CI: 76-89, p=1; 84%, 95% CI: 78-91, p=1) and external (82%, 95% CI: 76-89, p=0.82; 86%, 95% CI: 79-93, p=1) test datasets. Combining PI-RADSv2 and CAD findings could have avoided 41-52% of biopsies while missing 6-10% of ISUP≥2 cancers. The CAD system confirmed its robustness showing good discrimination of ISUP ≥2 cancers in a multicentric study involving 22 different scanners with highly heterogeneous image protocols. In per patient analysis, the CAD and the PI-RADSv2 had similar AUC values (76%, 95% CI: 70-82 vs 79%, 95% CI: 73-86; p=0.34) and sensitivities (86%, 95% CI: 76-96 vs 89%, 95% CI: 79-98 for PI-RADSv2 ≥4). The specificity of the CAD (62%, 95% CI: 53-70 vs 49%, 95% CI: 39-59 for PI-RADSv2 ≥4) could be used to complement the PI-RADSv2 score and potentially avoid 50% of biopsies, while missing 13% of ISUP ≥2 cancers. These findings were very similar to those reported in the single center test cohorts. Given its robustness, the CAD could then be exploited in more specific applications. The CAD first provided good discrimination of ISUP ≥2 cancers in patients under Active Surveillance. Its AUC (80%, 95% CI: 74-86) was similar to that of the PI-RADS score prospectively assigned by specialized uro-radiologists at the time of biopsy (81%, 95% CI: 74-87; p=0.96). After dichotomization, the CAD was more specific than the PI-RADS ≥3 (p<0.001) and the PI-RADS ≥4 scores (p<0.001). It could offer a solution to select patients who could safely avoid confirmatory or follow-up biopsy during Active Surveillance (25%), while missing 5% of ISUP≥2 cancers. Finally, the CAD was tested with the pre-prostatectomy mp-MRIs of 56 Japanese patients, from a population which is geographically distant from its training population and which is of interest because of its low prostate cancer incidence and mortality. The CAD obtained an AUC similar to the PI-RADSv2 score assigned by an experience radiologist in the PZ (80%, 95% CI: 71-90 vs 80%, 95% CI: 71-89; p=0.886) and in the TZ (79%, 95% CI: 66-90 vs 93%, 95%CI: 82-96; p=0.051). These promising and robust results across heterogeneous datasets suggest that the CAD could be used in clinical routine as a second opinion reader to help select the patients who could safely avoid biopsy. This CAD may assist less experience readers in the characterization of prostate lesions
Kober, Frank. "L'imagerie des gaz rares par résonance magnétique nucléaire". Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE19007.
Pełny tekst źródłaFortin, Alexandre. "Simulation d'expériences d'angiographie cérébrale par résonance magnétique". Thesis, Reims, 2017. http://www.theses.fr/2017REIMS038/document.
Pełny tekst źródłaDuring the last decades, magnetic resonance angiography has been used as a clinical routine for precise and non-invasive exploration of vessels, as well as for diagnosis of the most common neurovascular diseases. Several dedicated methods were developed to simulate specifically the process of angiographic acquisitions. Though, currently, most of advanced MRI simulators are exclusively specialized in static tissues imaging. This work was carried out to expand the possibilities of one of those simulators in order to propose a complete tool for MRI simulation of flow motion.The efficiency of this approach is proven by replicating the main angiographic pulse sequences and the most common flow artifacts. Finally, applications are provided on simulations of blood flow in realistic vessels geometries
Anne, Bertrand. "L'imagerie par résonance magnétique : les bases physiques, les qualités de l'image". Paris 5, 1995. http://www.theses.fr/1995PA05P037.
Pełny tekst źródłaBittoun, Jacques. "Un simulateur numérique d'imagerie par résonance magnétique nucléaire : conception et applications". Paris 11, 1987. http://www.theses.fr/1987PA112287.
Pełny tekst źródłaLeprince, Yann. "Imagerie des couches corticales par résonance magnétique à 7 teslas". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112022/document.
Pełny tekst źródłaThis thesis presents the development of a methodology for the analysis of the layered structure of the cerebral cortex, using high-field magnetic resonance imaging (7-tesla MRI). While cortical layers are traditionally studied using microscopic imaging of post-mortem tissue slices, the use a non-invasive technique such as MRI will enable in vivo studies, and thus allow new approaches beyond the use of classical architectural atlases such as Brodmann's.Two imaging methodologies have been used to acquire high-resolution images. First, a method based on super-resolution reconstruction from thick slices acquired in different geometries was developed for in vivo imaging. Second, a three-dimensional imaging sequence optimized for post-mortem tissue allowed imaging excised brain specimen.The main contribution of this thesis consists of a pair of methods that perform an automatic extraction of cortical profiles, which characterize the laminar architecture at any cortical location. In order to allow robust extraction of these profiles, an original model of the influence of cortical curvature was developed and implemented.These methods were tested and validated on multiple brain specimen. This work allows envisaging an automatic microarchitectural characterization of cortical areas, and even architectural parcellation, using high-field MRI
Didon, Jean-Philippe. "Recalage d'images cérébrales en IRM : application à la pathologie tumorale et vasculaire". Compiègne, 1996. http://www.theses.fr/1996COMPD867.
Pełny tekst źródłaMaubon, Antoine. "Imagerie en résonance magnétique nucléaire de l'épaule dégénérative". Montpellier 1, 1989. http://www.theses.fr/1989MON11216.
Pełny tekst źródłaBourgeois, Dominique. "Méthodologie en imagerie RMN : imagerie haute résolution, imagerie spectroscopique, imagerie de débits". Université Joseph Fourier (Grenoble), 1990. http://www.theses.fr/1990GRE19005.
Pełny tekst źródłaMaurer, Pierre. "Apports de l'imagerie par résonance magnétique du médiastin". Montpellier 1, 1989. http://www.theses.fr/1989MON11168.
Pełny tekst źródłaMantilla, Jauregui Juan José. "Caractérisation de pathologies cardiaques en Imagerie par Résonance Magnétique par approches parcimonieuses". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S073/document.
Pełny tekst źródłaThis work concerns the use of sparse representation and Dictionary Learning (DL) in order to get insights about the diseased heart in the context of Cardiovascular Diseases (CVDs). Specifically, this work focuses on 1) assessment of Left Ventricle (LV) wall motion in patients with heart failure and 2) fibrosis detection in patients with hypertrophic cardiomyopathy (HCM). In the context of heart failure (HF) patients, the work focuses on LV wall motion analysis in cardiac cine-MRI. The first contribution in this topic is a feature extraction method that exploits the partial information obtained from all temporal cardiac phases and anatomical segments in a spatio-temporal representation from sequences cine-MRI in short-axis view. These features correspond to spatio-temporal profiles in different anatomical segments of the LV. The proposed representations exploit information of the LV wall motion without segmentation needs. Three representations are proposed : 1) diametrical spatio-temporal profiles where radial motions of LV’s walls are observed at the same time in opposite anatomical segments 2) radial spatiotemporal profiles where motion of LV’s walls is observed for each segment of the LV cavity and 3) quantitative parameters extracted from the radial spatio-temporal profiles. A second contribution involves the use of these features as input atoms in the training of discriminative dictionaries to classify normal or abnormal regional LV motion. We propose two levels of evaluation, a first one where the global status of the subject (normal/pathologic) is used as ground truth to label the proposed spatio-temporal representations, and a second one where local strain information obtained from 2D Speckle Tracking Echocardiography (STE), is taken as ground truth to label the proposed features, where a profile is classified as normal or abnormal (akinetic or hypokinetic cases). In the context of Hypertrophic cardiomyopathy (HCM), we address the problem of fibrosis detection in Late Gadolinium Enhanced LGE-Short axis (SAX) images by using a sparse-based clustering approach and DL. In this framework, random image patches are taken as input atoms in order to train a classifier based on the sparse coefficients obtained with a DL approach based on kernels. For a new test LG-SAX image, the label of each pixel is predicted by using the trained classifier allowing the detection of fibrosis. A subsequent postprocessing step allows the spatial localization of fibrosis that is represented according to the American Heart Association (AHA) 17-segment model and a quantification of fibrosis in the LV myocardium
Elbes, 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
Dinet, Bernard. "Anesthésie de l'enfant par Methohexital pour l'examen IRM : [Imagerie par résonance magnétique]". Bordeaux 2, 1990. http://www.theses.fr/1990BOR25253.
Pełny tekst źródłaGuo, Jia. "Machine learning in automated analysis of human aorta using innovative 4D flow MRI". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS591.pdf.
Pełny tekst źródłaThe aorta is the main artery of the human body and plays a key role in the cardiovascular system as it conveys oxygenated blood to our organs while ensuring constant and continuous blood flow and regulated arterial pressures despite the pulsatile and recurrent nature of the heart ejection. This cushioning function of the aorta can however be impaired by various diseases which stiffen the aorta thus reducing its elastic efficiency. This aortic stiffening is often characterized by structural and mechanical changes of the aortic wall interplaying with circulating blood flow disorganization and is known to play a significant role in cardiovascular disease development and progression towards fatal events (aortic wall rupture). Magnetic Resonance Imaging (MRI) is a non-invasive and non-irradiating imaging modality able to provide both aortic anatomy (angiography data) and blood flow dynamics (4D flow data) through volumetric acquisitions. Anatomic angiography data are acquired on a single phase of the cardiac cycle but have a high spatial resolution and contrast. They are usually used in clinical routine to extract morphological indices (diameters on selected slices) and to visualize geometrical malformation (stenosis, dilation, abnormal valves). 4D flow datasets consist in the acquisition of circulating blood flow X, Y and Z velocity components in all aortic voxels during the entire cardiac cycle, but with a lower resolution and overall contrast. In the clinical routine, these data can be visualized but the lack of segmentation tools hinders the extraction of quantitative measures, although they will be of major usefulness for the patient. In our laboratory (Laboratory of Biomedical Imaging, Cardiovascular Imaging team), we have recently developed a semi-automated technique (MIMOSA software) which is able to reliably detect 3D aortic borders on angiographic images. This technique has been applied on the data of 400 patients including: controls with a wide age range (20 to 80 years), patients with aortic dilation, and female patients with abnormally small aorta because of their Turner syndrome (clinical data are made available through our tight collaboration with Pitié-Salpêtrière Hospital). To summarize: 1) there is an urgent need for automated segmentation of the above-mentioned MRI images to accurately quantify aortic morphology, function and well as hemodynamics
Mao, Lili. "Techniques rapides de l'imagerie par résonance magnétique en régime d'équilibre dynamique". Paris 11, 1988. http://www.theses.fr/1988PA112180.
Pełny tekst źródłaBeaumont, Stéphane. "Les artéfacts de champ magnétique en imagerie par résonance magnétique nucléaire (I. R. M. )". Toulouse 3, 1993. http://www.theses.fr/1993TOU30016.
Pełny tekst źródłaHeritier, Bernard. "Contrôle en temps réel d'un imageur par résonance magnétique". Paris 11, 1987. http://www.theses.fr/1987PA112327.
Pełny tekst źródłaGrenier, Denis. "Micro-imagerie RMN de milieux quasi-solides : exemple d'application à l'imagerie ostéoarticulaire". Lyon 1, 1999. http://www.theses.fr/1999LYO10004.
Pełny tekst źródłaDeloison, Benjamin. "Imagerie fonctionnelle placentaire par résonance magnétique : étude de la perfusion placentaire". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112256.
Pełny tekst źródłaPlacental insufficiency is a serious medical condition with a diagnosis made usually too late to prevent introduction of effective therapies. The aim of this thesis is to develop, in pregnant rats and translate to humans, functional MRI (fMRI) tools allowing quantification of placental perfusion in clinical practice.Materials and Methods: Three studies using fMRI are part of this thesis. The first two were performed on a murine model. A dynamic sequence with injection of a contrast agent (DCE) has been developed with an iron oxide particle (SPIO) in a surgical model of chronic placental hypoperfusion with placental perfusion measurement (f) in ml / min / 100 ml and placental fractionnal volume (Vb) in %. Another technique of fMRI was developed with Arterial Spin Labeling (ASL) to estimate placental perfusion in ml / min / 100g without injection of contrast media.The latest study was a translational research. It consisted in the development of a dynamic sequence with injection of gadolinium chelate, in order to obtain perfusion (f) in ml / min / 100 ml and placental fractionnal volume (Vb) in %. We also studied maternal and fetal pharmacokinetics of gadolinium chelate.Results: In animals with SPIO DCE, our study allowed us to show that it is possible to use the T1 effect of SPIO to characterize the placental microcirculation by f = 159.4 ml / min / 100ml (+ / - 54.6) and Vb = 39.2% (11.9 +/-) for 31 « normal » placentas. In case of IUGR, f decreases significantly for the 23 examined placentas (f = 108.1 ml / min / 100ml +/- 41, p = 0.004), whereas the volume fraction placenta is not modified (Vb = 42 +/- 16.7 8 %, p = 0.24). ASL has allowed us to estimate placental perfusion for 47 placentas under physiological conditions, with an estimated perfusion of 146.8 ml / min / 100 g (70.1 +/-).In humans, 14 placentas were studied with an estimated perfusion of 183 ml / min / 100ml (+/- 144) and we also identified two types of placental kinetic enhancement (early and intense and later and less intense). Pharmacokinetics have allowed us to study quantitatively the transfer of gadolinium chelate in the fetus. This transfer is low compared to the initial concentration of Dotarem® : fetal blood concentration is 18.1x10-6%, concentration in amniotic fluid is 242.8 x10-6 % and 0.3% of the Dotarem® initial dose is present in the placenta approximately 70 hours after injection.Conclusion: This study illustrates the variety of functional MRI techniques available for placental study. Placental perfusion can be quantified by DCE with an iron oxide particle (SPIO) or without injection of contrast in ASL, in a rat model. The study of placental perfusion in humans is also possible in DCE with gadolinium chelates
Yassine, Mohamad Mouhib. "Imagerie de la peau par résonance magnétique nucléaire à 0,1 Tesla". Paris 11, 1988. http://www.theses.fr/1988PA112362.
Pełny tekst źródłaYankam, Njiwa Josiane Adrienne. "Reconstruction d'images de résonance magnétique à partir de l'espace k partiel". Lyon, INSA, 2007. http://theses.insa-lyon.fr/publication/2007ISAL0055/these.pdf.
Pełny tekst źródłaWith the aim of avoiding the bad influence which the movement could have on the quality of the images, short acquisition time is mandatory in magnetic resonance imaging (MRI). Especially for sick patients who have problems holding their breath during examination, it becomes consequently imperative to collect necessary information as faster as possible in certain studies, such as those carried out in cardiac imaging. Partial k-space acquisition is a common way used to shorten the data acquisition time in MRI applications. For the sake of short acquisition time and/or increased spatial resolution of the reconstructed images, several methods have already been proposed, which partially acquired the k-space data. These methods use a priori information to recover the missing data. This manuscript presents three MRI reconstruction methods using partial k-space data. The first proposed method is dedicated to the reconstruction of static objects or organs, while the two others are devoted to the reconstruction of dynamic organs (application to cardiac imaging). These three methods are based on the use, in the reconstruction algorithm, of the analytic image concept, combined in the case of the static images with the exploitation of the redundancies in the k-space data, and with the use of the temporal redundancies associated to the data substitution, for the moving organs. These methods were evaluated, within the framework of static images reconstruction, by experiments on simulated images to which were added a slowly varying phase term to destroy the Hermitian symmetry, and also on physical phantoms and true human brain images. The two other methods were evaluated by experiments on true human cardiac sequences. The proposed reconstruction schema allows achieving a reduction of the acquisition time by a factor of 2, for the static images reconstruction. With regard to the dynamic images, a reduction of the acquisition time by a factor of 4 was carried out, while maintaining a good reconstruction quality, as well on visual meaning as quantitative meaning (good signal to noise ratio, low error values)
Tizón-Marcos, Helena. "Trabeculated myocardium in healthy adults : a first step in understanding the diagnosis of non-compaction cardiomyopathy by magnetic resonance". Master's thesis, Université Laval, 2012. http://hdl.handle.net/20.500.11794/23705.
Pełny tekst źródłaNon-compaction cardiomyopathy (NCC) is a rare entity that is currently diagnosed for the most part by echocardiography in cases of an increased layer of trabeculated myocardium. Recently, magnetic resonance imaging (MRI) became the gold standard imaging technique in the study of cardiac function and morphology due to its high spatial and temporal resolution. However, diagnostic NCC criteria developped for echocardiography have been directly applied to MRI in the abscence of a standard definition of trabeculated myocardium. This direct application of echocardiography criteria to MRI may have led to an increased incidence of new NCC cases. The aim of this present work is to clarify clinical practice by determining normality by MRI in terms of presence and distribution of trabeculated myocardium in healthy adults and determine if any association exist between the presence and extension of trabeculated myocardium and cardiac function.
Ries, Mario. "Diffusion MRI of human spine and kidney : Technological aspects and interpretation". Bordeaux 1, 2001. http://www.theses.fr/2001BOR12360.
Pełny tekst źródłaStortz, Yvon. "Synthèse et développement d'agents de contraste bioactifs pour la visualisation in vivo de l'expression de gènes par Imagerie par Résonance Magnétique". Lyon, École normale supérieure (sciences), 2006. http://www.theses.fr/2006ENSL0381.
Pełny tekst źródłaBadr, Sammy. "Quantification in vivo de l’adiposité médullaire chez l’Homme par imagerie par résonance magnétique". Thesis, Lille, 2019. https://pepite-depot.univ-lille.fr/LIBRE/EDBSL/2019/2019LILUS058.pdf.
Pełny tekst źródłaBone marrow adiposity (BMA) is an underestimated tissue playing a key role in bonehomeostasis. To date, only magnetic resonance imaging (MRI) is able to exploreadequately and non-invasively this tissue in vivo. This work aims to clarify the mainbiases to take into account, to illustrate the value of BMA quantification to understandpathophysiological mechanisms, and finally, to promote its use for clinical purposes.The first axis of this work relies on a review of two fundamental methods to exploreBMA : proton magnetic resonance spectroscopy, and chemical shift encoding-basedwater-fat imaging. The use of these techniques is constrained by the differential magneticproperties of water and lipids, as well as the multiple interfaces between trabeculaeand bone marrow, fostering local magnetic inhomogeneities and reducingthe accuracy of BMA quantification. Clarifications on the major technical biases toconsider have been incorporated in a white paper written in collaboration with theMethodology Workgroup of the International Bone Marrow Adiposity Society.The second part of this work was based on the exploration of a paradoxical disease,anorexia nervosa, which affects multiple fat compartments. As a matter of fact, thedrastic depletion of peripheral adipose tissues contrasts with BMA expansion in anorexicpatients. Through a case-control study, the spectral characteristics of BMAat the hip of underweight (body mass index < 17.5 kg/m2) and weight-recoveredanorexic women have been compared to healthy volunteers. While no difference inthe spectral BMA profile was observed between anorexic patients, bone marrow fatfraction was significantly higher and the apparent lipid unsaturation levels lower inpatients compared to controls. Persistence of an abnormal BMA may take part in theincreased fracture risk in anorexic patients, even after weight recovery. This work hasbeen accepted for publication.Finally, although spectroscopic methods are the gold-standard for BMA quantification,its promotion in routine requires a simplification of its exploration. Chemicalshift encoding-based water-fat imaging appears to be a pertinent alternative approach.To illustrate its use for clinical purposes, a new case-control study, performed on postmenopausalwomen, has been initiated. Comparisons of BMA characteristics betweenwomen with a recent osteoporotic fracture and age-matched controls would providenew diagnostic elements for the evaluation of the fracture risk in postmenopausalosteoporosis. This is an on-going project, with preliminary results.The 3 axes of this research project highlight the clinical potential of BMA quantification.In the future, a multifactorial evaluation of bone, integrating data from themineral and organic compartments, would promote accurate expertise of bone healthand a better estimate of the fracture risk, especially in women with anorexia nervosaor postmenopausal osteoporosis
Hernandez-Hoyos, Marcela. "Segmentation anisotrope 3D pour la quantification en imagerie vasculaire par résonance magnétique". Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0039/these.pdf.
Pełny tekst źródłaThe purpose of this work is the segmentation of three-dimensional vascular images obtained by magnetic resonance. Clinical application in view is the quantification of arterial stenoses. We propose a method for vessel segmentation, divided into two stpes: vessel axis extraction and detection of vessel contours in the planes locally perpendicular to the axis. Our main contribution is automatic vessel centerline extraction method based on extensible-skeleton model whose growth is driven by multi-scale analysis of the inertia tensor. This analysis provides information about the orientation, diameter and local shape of the vessel in each point of its axis. The vessel is roughly reconstructed using a binary volume composed by a union of spheroids centered on the axis, oriented according to the vessel local orientation and adapted to the vessel local size. Based on the same theoretical principles, we propose a method for semi-automatic detection of arterial bifurcations. Recursive processing of bifurcations aims at extraction of the entire vascular tree. Calculation of stenosis parameters is based on the extraction of planar contours. To this purpose, we implemented two algorithms. The first one is based on iso-contours extraction using an adaptive local threshold. The second one uses a normalized-length active contour model. These algorithms have been implemented in user-friendly software called MARACAS (Magnetic Resonance Angiography Computer Assisted Analysis) that underwent a clinic pre-validation on images of 6 vascular phantoms and clinical data of 27 patients
Lepetit-Coiffé, Matthieu. "La thérapie mini invasive par hyperthermie locale guidée par imagerie par résonance nucléaire : développement pour le chauffage par radiofréquence". Bordeaux 1, 2006. http://www.theses.fr/2006BOR13332.
Pełny tekst źródłaCallot, Virginie. "Encapsulation et vectorisation de l'hélium3 hyperpolarisé : application à l'IRM de la perfusion tissulaire". Lyon 1, 2001. http://www.theses.fr/2001LYO10187.
Pełny tekst źródłaKlein, Olivier. "Microscopie à résonance magnétique detectée mécaniquement". Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00006836.
Pełny tekst źródłaLoeuille, Damien. "Micro-imagerie RMN du cartilage". Nancy 1, 2002. http://www.theses.fr/2002NAN11307.
Pełny tekst źródłaWatrin-Pinzano, Astrid. "Influence des composés matriciels sur le signal IRM du cartilage". Nancy 1, 2001. http://www.theses.fr/2001NAN11318.
Pełny tekst źródłaGauthier, Christophe. "Étude des différences liées au sexe dans les corrélats cérébraux d'une tâche de langage et d'une tâche visuo-spatiale par le recours à l'Imagerie par Résonance Magnétique fonctionnelle (IRMf)". Montpellier 3, 2008. http://www.theses.fr/2008MON30026.
Pełny tekst źródłaThe aim was to test the main sex effect and the (high or low) performance level of verbal fluency (VF) and a combination of these two on cerebral correlates related to VF. Four samples of 11 healthy students selected according to their sex and performances carried out a silent phonological VF task with the help of functional Magnetic Resonance Imaging (fMRI). The groups showed activation in the frontal, occipital and parietal lobes the cerebellum, the thalamus and basal ganglia. The analyses indicated : a sex-performance interaction on the amount of activation in several areas, a sex effect for others – activation was greater for men - a performance effect for two regions. Both sex and performance should be considered in studies on VF cerebral correlates. Working from 15 fMRI studies on a Mental Rotation (MR) task, strict grouping criteria were applied. Two distinct study corpuses were constituted in order to determine which robust cerebral correlates of MR were common to both men and women and which were specific to each sex. Whatever the sex, the intraparietal and parieto-occipital sulci complex was systematically involved bilaterally and the involvement of the pre-motor areas was less common. The right inferior frontal gyrus tended to be more commonly involved for the groups of women than men whereas the lateral occipital complex was involved for women only. The question was to know whether these differences persisted depending on performance
Crémillieux, Yannick. "Méthodologies pour l'imagerie par résonance magnétique utilisant la technique de projection-reconstruction". Lyon 1, 1994. http://www.theses.fr/1994LYO10230.
Pełny tekst źródłaBourgeois, Marc. "Correction des mouvements intra-image en imagerie d'activation cérébrale par résonance magnétique". Lyon 1, 1999. http://www.theses.fr/1999LYO10143.
Pełny tekst źródłaDufrenois, Franck. "Etude de techniques de reconstruction surfacique en trois dimensions d'objets biologiques complexes par modèles déformables : Réalisation d'une chaîne de reconstruction de l'arbre vasculaire cérébral à partir d'acquisitions I.R.M". Lille 1, 1994. http://www.theses.fr/1994LIL10179.
Pełny tekst źródłaChipon, Emilie. "IRM fonctionnelle quantitative appliquée à la vasoréacivité cérébrale". Grenoble 1, 2009. http://www.theses.fr/2009GRE10003.
Pełny tekst źródłaIn neurosciences and medicine, functional imaging of brain perfusion is a mean to characterize regional variations of neuro-vascular coupling and alterations of the vasoreactivity to circulating gases in patients. Arterial Spin Labeling (ASL) is an MRI method which provides a quantitative and reproductible measure of brain perfusion and its dynamical changes, without the need for injection of contrast agents. This thesis presents the implementation of an MRI sequence for the quantification of cerebral blood flow by ASL and its optimization for the study of cerebral vasoreactivity. To obtain a quantitative measure with maximal sensitivity, numerical simulations and experiments on healthy subjects have allowed to optimize: the amplitude of RF pulses, the inversion pulse delays to suppress static signal, the limits of the position of the tagging band with respect to the RF resonator, the minimal allowable gap between tagging band and region of interest, the bolus duration and delay time before acquisition. An original method to rapidly caracterize the bolus of labeled blood in each session has been developed to provide an optimal parametrization of the sequence for each subject. These methods have been used to characterize the effects of inhalation of oxygen and carbogen mixtures with varying CO2 concentrations on perfusion in healthy subjects. In parallel, the same perfusion methods are used in a study to characterize cerebral vasoreactivity in Alzheimer's Disease patients
Auclair, David. "Neuro-anatomie fonctionnelle et applications thérapeutiques de la modification du rétro-contrôle visuel du mouvement". Lyon 1, 2005. http://www.theses.fr/2005LYO10055.
Pełny tekst źródłaAndrieu, Patrice. "Dispositif de stimulation olfactive pour l'investion en imagerie par résonance magnétique fonctionelle". Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-01024127.
Pełny tekst źródła