Rozprawy doktorskie na temat „Imagerie par résonance magnétique – Emploi en diagnostic – Innovation”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 15 najlepszych rozpraw doktorskich naukowych na temat „Imagerie par résonance magnétique – Emploi en diagnostic – 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.
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
Trillaud, Hervé. "Distribution intrarénale des nanoparticules d'oxyde de fer en imagerie par résonance magnétique". Bordeaux 2, 1993. http://www.theses.fr/1993BOR23022.
Pełny tekst źródłaConstans, Jean-Marc. "Intérêt du gadolinium dans les spondylodiscites infectieuses et dans leur suivi évolutif". Caen, 1991. http://www.theses.fr/1991CAEN3028.
Pełny tekst źródłaLehaire, Jérôme. "Détection et caractérisation du cancer de la prostate par images IRM 1.5T multiparamétriques". Electronic Thesis or Diss., Lyon, 2016. http://www.theses.fr/2016LYSE1174.
Pełny tekst źródłaProstate cancer is the most frequent and the fourth leading cause of mortality in France. Actual diagnosis methods are often insufficient in order to detect and precisely locate cancer. Multiparametrics MRI is now one of the most promising method for accurate follow-up of the disease. However, the visual interpretation of MRI is not easy and it is shown that there is strongvariability among expert radiologists to perform diagnosis, especially when MR sequences are contradictory. Under these circumstances, a strong interest is for Computer-aided diagnosis systems (CAD) aiming at assisting expert radiologist in their final decision. This thesis presents our work toward the conception of a CADe which final goal is to provide a cancer probability map to expertradiologist. This study is based on a rich dataset of 49 patients made of T2w, dynamic and diffusion MR images. The ground truth was obtained through strict process of annotations and correlation between histology and MRI. This thesis focuses both for cancer detection and characterization in order to provide a cancer probability map correlated to cancer aggressiveness (Gleason score). To that end we used a dictionary learning method to extract new features to better characterize cancer aggressiveness signatures as well as image features. Those features are then used as an input to Support Vector Machines (SVM) and Logistic Regression (LR) classifiers to produce a cancer probability map. We then focused on discriminating agressive cancers (Gleason score >6) from other tissues and provided an analysis of the correlation between cancer aggressiveness and probabilities. Our work conclude on a strong capability to distinguish agressive cancer from other tissues but fails to precisely distinguish different grades of cancers
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
Beaussier, Hélène. "Pharmacologie et mécanique de la plaque d'athérosclérose". Paris 5, 2010. http://www.theses.fr/2010PA05P619.
Pełny tekst źródłaOur research is based on the role of arterial stiffness in the atherosclerotic carotid wall mechanics to understand plaque rupture in essential hypertensive patients. All mechanical parameters were measured on the common carotid artery (CCA) segment by a non-invasive echotracking system, the ArtLab®. We have modelled the in vivo mechanical behavior of human CCAs to quantify contributions of micro-constituents with age and hypertension. Arterial stiffness could explain changes in mechanical characteristics of wall micro-constituents in hypertension and atherosclerotic arterial wall behaviour in response to mechanical strains. Two opposite patterns of longitudinal bending strain (BS) has been shown in atherosclerotic plaques on the CCA: inward BS (pattern B), i. E. Lower radial strain at the plaque level than adjacent segment, and outward BS (pattern A). We have defined determinants of the pattern B (Beaussier, Hypertension 2008): essential hypertension, outer remodelling and absence of renin-angiotensin system (RAS) blockers. Arterial wall of hypertensive patients are less elastic at the site of the plaque, exposing the plaque to a greater risk of rupture. RAS blockers could protect against inward BS. We have correlated the arterial mechanics of carotid atherosclerotic plaques (echotracking) with their composition (MRI). We have shown that inward BS pattern are more often associated with complex plaques, with lipid rich core and with an outer remodelling; these are structural characteristics of “vulnerable” plaque, prone to rupture. This suggested that inward BS is a mechanical feature of vulnerable plaques
Nel, Janske. "Lipid nanocapsules as a theranostic tool Preparation and evaluation of trityl-loaded lipid nanocapsules as oxygen sensors for Electron Paramagnetic Resonance oximetry Lipid nanocapsules as in vivo oxygen sensors using Magnetic Resonance Imaging". Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0070.
Pełny tekst źródłaHypoxia is one of the most challenging aspects of the tumour microenvironment. The phenomenon occurs due to abnormal vasculature and an exacerbated metabolism, and leads to highly malignant cells resistant to radio- and cyto-toxic therapy. As such, hypoxia is of major concern and prompted our novel approach in using lipid nanocapsules (LNCs) as an oxygen sensor. LNCs have been demonstrated as excellent core-shell nanocarriers, capable of encapsulating drugs within their lipidic core and avoiding the immune system due to their PEGylated shell, thus enabling treatment of highly aggressive tumours. We hypothesised that the lipidic-core of LNCs could also be used to assess the O2 environment in tissue. Indeed, because O2 solubility is greater in lipids than in water, any subtle changes in tissue O2 will be heightened in the lipidic LNC core. Consequently, we encapsulated a lipophilic paramagnetic probe, e.g. tetrathiatriarylmethyl (TAM), and demonstrated its response to variations in O2 in vitro, using Electron Paramagnetic Resonance (EPR), indicating the permeability of LNCs to O2. We applied the TAM-LNCs to an in vivo normal tissue model (gastrocnemius mouse muscle) and pathological model (sarcoma tumour). Herein, free TAM was rapidly reduced and no O2 measurement was possible, however, our TAM-LNC system exhibited a half-life of over an hour and enabled real-time measurements whilst animals were breathing air and during a carbogen gas (95 % O2, 5 % CO2) breathing challenge. Moreover, the lipidic-core nature of the LNCs was exploited to image tissue oxygenation using Magnetic Resonance Imaging (MRI), specifically the MOBILE sequence which enabled the mapping of O2-induced T1 relaxation rate changes in lipids. Using a single dose of LNCs, we were able to portray the change in T1 between air breathing and the carbogen challenge, and image the heterogeneous nature of hypoxia in murine normal tissue and pathological tumour models. In conclusion, we demonstrated the feasibility of using LNCs as a diagnostic tool for assessing hypoxia in both normal and pathological tissues
Histace, Aymeric. "Détection et suivi robustes de structures sur des séquences d'images : application à l'IRM cardiaque marquée". Angers, 2004. http://www.theses.fr/2004ANGE0022.
Pełny tekst źródłaThis thesis is dealing with the detection and the follow-up of structures in image sequences. We show that the integration of original external energies in a simple active contours model can lead to precise and reliable data detections. This work is presented through a particular application : the study of tagged cardiac MRI sequences. The study of those sequences can be divided into two parts : a detection and a follow-up of the internal and external boundaries of the Left Ventricle and a detection and a follow-up of the grid of tags. For the achievement of the first step, we propose the integration of a particular external energy which generation is based on a texture analysis of the tagged MRI. For the second, we propose an anisotropic diffusion of the images, which leading equation is based on an informational formalism using the Extreme Physical Information process. All the obtained results has been validated by a medical expert
Antunes, Neves Ana Luisa. "Application au domaine biomédical des moyens de caractérisation électromagnétique de matériaux dans le spectre des micro-ondes". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0320/document.
Pełny tekst źródłaThe penetration capacity of the electromagnetic (EM) waves in matter or biological tissues allows exploring media non-destructively. Concerning the public health sector, improving the quality of life has become one of the greatest concerns of nowadays society. EM wave research on different media and biological tissues shows a great potential for diagnostic applications and eventually for therapeutically applications. In this doctoral thesis, we focus on the vast domain of the biomedical applications of wave-matter interactions, based on the knowledge of the electromagnetic properties of matter, the complex permittivity and the conductivity. On a first instance, we address the emerging domain of ultra-high field MRI (Magnetic Resonance Imaging), which nowadays puts effort into the clinical implementation of 7T devices. Firstly our purpose is to produce an anthropomorphic head model, composed of the brain’s different layers, and taking into account the electromagnetic properties and the proton relaxation times inherent to each tissue. These realistic head models allow to evaluate the newly developed protocols for these ultra-high field devices. Secondly, we have studied and developed field homogenization devices, which allow brightening the shadow areas displayed in some MRI images, such as the cerebellum and the temporal lobes in brain imaging at 7T. This procedure, named Passive Shimming, is based on the use of high permittivity dielectric pads composed of Barium Titanate, which focalize the field to the areas where normally the wavelength in insufficient to generate a homogeneous signal distribution
Crombé, Amandine. "Développement des approches radiomics à visées diagnostique et pronostique pour la prise en charge de patients atteints des sarcomes des tissus mous". Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0059.
Pełny tekst źródłaSoft-tissue sarcomas (STS) are malignant ubiquitous mesenchymal tumors that are characterized by their heterogeneity at several levels, i.e. in terms of clinical presentation, radiological presentation, histology, molecular features and prognosis. Magnetic resonance imaging (MRI) with a contrast-agent injection is the imaging of reference for these tumors. MRI enables to perform the local staging, the evaluation of response to treatment, to plan the surgery and to look for local relapse. Furthermore, MRI can access non-invasively to the whole tumor in situ and in vivo which is complementary to histopathological and molecular analyses requiring invasive biopsy samples at risk of sampling bias. However, no imaging biomarker dedicated to STS has been validated so far. Meanwhile, technical innovations have been developed, namely: (i) alternative imaging modalities or MRI sequences that can quantify intratumoral physiopathological phenomenon; (ii) image analysis tools that can quantify radiological phenotypes better than human’s eyes through hundreds of textural and shape quantitative features (named radiomics features); and (iii) mathematical algorithms that can integrate all these information into predictive models (: machine-learning). Radiomics approaches correspond to the development of predictive models based on machine-learning algorithms and radiomics features, eventually combined with other clinical, pathological and molecular features. The aim of this thesis was to put these innovations into practice and to optimize them in order to improve the diagnostic and therapeutic managements of patients with STS.In the first part, we combined radiological and radiomics features extracted from the baseline structural MRIs of patients with a locally-advanced subtype of STS in order to build a radiomics signature that could help to identify patients with higher risk of metastatic relapse and may benefit from neoadjuvant treatments. In the second part, we elaborated a model based on the early changes in intratumoral heterogeneity (: delta-radiomics) on structural MRIs of patients with locally-advanced high-grade STS treated with neoadjuvant chemotherapy, in order to rapidly identify patients who do not respond to treatment and would benefit from early therapeutic adjustments. In the last part, we tried to better identify and control potential bias in radiomics approaches in order to optimize the predictive models based on radiomics features
Lehaire, Jérôme. "Détection et caractérisation du cancer de la prostate par images IRM 1.5T multiparamétriques". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1174/document.
Pełny tekst źródłaProstate cancer is the most frequent and the fourth leading cause of mortality in France. Actual diagnosis methods are often insufficient in order to detect and precisely locate cancer. Multiparametrics MRI is now one of the most promising method for accurate follow-up of the disease. However, the visual interpretation of MRI is not easy and it is shown that there is strongvariability among expert radiologists to perform diagnosis, especially when MR sequences are contradictory. Under these circumstances, a strong interest is for Computer-aided diagnosis systems (CAD) aiming at assisting expert radiologist in their final decision. This thesis presents our work toward the conception of a CADe which final goal is to provide a cancer probability map to expertradiologist. This study is based on a rich dataset of 49 patients made of T2w, dynamic and diffusion MR images. The ground truth was obtained through strict process of annotations and correlation between histology and MRI. This thesis focuses both for cancer detection and characterization in order to provide a cancer probability map correlated to cancer aggressiveness (Gleason score). To that end we used a dictionary learning method to extract new features to better characterize cancer aggressiveness signatures as well as image features. Those features are then used as an input to Support Vector Machines (SVM) and Logistic Regression (LR) classifiers to produce a cancer probability map. We then focused on discriminating agressive cancers (Gleason score >6) from other tissues and provided an analysis of the correlation between cancer aggressiveness and probabilities. Our work conclude on a strong capability to distinguish agressive cancer from other tissues but fails to precisely distinguish different grades of cancers
Tîlmaciu, Carmen-Mihaela. "Synthèse et remplissage de nanotubes de carbone double-parois pour des applications biomédicales". Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1169/.
Pełny tekst źródłaNarrow double-walled CNT (DWNT) were prepared by catalytic chemical vapour deposition (CCVD), using a MgO-based catalyst, which was reduced at 1000 °C in a mixture of H2/CH4, containing 18 mol % of CH4. The selectivity towards DWNT is ca. 80%. Before and after purification in air, these tubes with inner diameters < ou = 2 nm were filled by capillary action with iron and cobalt precursors (FeI2, FeCl2, FeCp2 or CoI2) in melted phases, followed by reduction in H2, in order to prepare magnetic nanowires inside the DWNT for hyperthermia application. The Mössbauer characterizations after reduction of the iron halides@DWNT in H2, have evidenced the presence of superparamagnetic nanoparticles of Fe(III) oxides (SPION), which present very high interest, as they are sensitive to magnetic fields, without retaining magnetisation after removal of the latter. In parallel, after reduction of the CoI2@DWNT, AGM and SQUID measurements revealed the presence of ferromagnetic nanowires of cobalt confined in DWNT (collaboration with IFW-Dresden, Germany). Using the same method of filling in melted phase, gadonanotubes (Gd3+@DWNT) were synthesized for magnetic resonance imaging (MRI). Preliminary measurements of relaxation times and the control of possible leaks of metal outside DWNT were achieved on several samples with different concentrations of gadolinium. The results are encouraging: Gd3+@DWNT samples present a good stability in time (over twenty three days) and high relaxivities (about five times greater than the current main clinical agents) - collaboration with the Hospital of Purpan-Toulouse, France. Filling in solution with chloroquine diphosphate salt, an antimalarian drug was also successfully achieved. Luciferase assay, MTT toxicity test, as well as HRTEM, EDX and elemental analysis were performed, in order to prove the filling and to quantify the percent of the drug in the sample (collaboration with the University of Surrey, England)
Termenon, Conde Maite. "Analyse par graphes de la connectivité fonctionnelle de repos par IRM : vers de nouveaux biomarqueurs de la récupération fonctionnelle dans l'AVC". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS023/document.
Pełny tekst źródłaNeumann, Markus. "Automatic multimodal real-time tracking for image plane alignment in interventional Magnetic Resonance Imaging". Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01038023.
Pełny tekst źródłaGhose, Soumya. "Robust image segmentation applied to magnetic resonance and ultrasound images of the prostate". Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/98524.
Pełny tekst źródłaLa segmentació de la pròstata en imatge d'ultrasò (US) i de ressonància magnètica (MRI) permet l'estimació del volum, el registre multi-modal i la planificació quirúrgica de biòpsies guiades per imatge. L'objectiu d'aquesta tesi és el desenvolupament d'algorismes automàtics per a la segmentació de la pròstata en aquestes modalitats. Es proposa un aprenentatge automàtic inical per obtenir una primera classificació de la pròstata que permet, a continuació, la inicialització i evolució de diferents models deformables. Per imatges d'US, es proposen un model explícit basat en forma i informació regional i un model implícit basat en la minimització d'una funció d'energia. En MRI, les probalitats inicials es fusionen amb una imatge de probabilitat provinent d'una segmentació basada en atlas, i la minimització es realitza mitjançant tècniques de grafs. El resultat final és una significant millora dels algorismes actuals en ambdues modalitats d'imatge.