Dissertations / Theses on the topic 'Imagerie cérébrale 3 D'
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Kadalie, Emile. "Development of multi-parametric human MRI at 3T." Electronic Thesis or Diss., Bordeaux, 2023. http://www.theses.fr/2023BORD0493.
Magnetic Resonance Imaging (MRI) is a method of choice for the diagnosis, prognosis and monitoring of pathologies in soft tissues. Indeed, strong contrasts between tissues are obtained and can be modulated on demand. This imaging technique has not shown any harmful influence, enabling repetitive high-resolution exams.Quantitative MRI (qMRI) has become incredibly interesting these last ten years, as it provides maps in which each pixel contains a measurement of a physical parameter. As such, contrarily to conventional images obtained on a gray scale, this MR quantification can be employed to obtain objective interpretations of the images, and to provide a scale for comparing time points and patients.Among the physics parameters that can be quantified, the longitudinal (T1) and the transversal (T2) relaxation times are the most common.The Dual Echo Steady State (DESS) sequence has often been used in musculo-skeletal MRI to rapidly obtain high-contrast morphological images and 3D quantitative T2 mapping. By acquiring two distinct steady-state free precession echoes, two images with different contrasts are built, whose ratio can be used to procure T2 maps by matching it to a computed dictionary of many simulated signals. Nonetheless, the sequence has often been described as sensitive to physiological motion, generating artifacts as well as discrepancies in T2 values. Consequently, the main objective of my work was to implement a rapid 3D DESS sequence for brain imaging that enables T2 estimation accurately and with high repeatability at 3T.To do so, I first identified the cause of the ghosting artifact present in the DESS brain images, through the insertion of a Self-Gating (SG) module. As, its phase was correlated to the signal retrieved from a respiratory belt, B0 variations due to breathing were consequently identified as the source of the ghosting on the brain images.To correct this artifact, a Compressed Sensing dedicated trajectory was implemented so as to retrospectively bin the data into multiple respiratory phases, and reconstruct undersampled k-spaces into images with high quality. To increase the repeatability of the method, the conventional Cartesian encoding was replaced by a Spiral Cartesian encoding, which further distributed the artifact as noise on the images. 3D T2 maps were then acquired with a spatial resolution of 1.2mm isotropic, and were of high quality and repeatable on all the volunteers.The new methodology was then implemented on a 1.5T and a 7T Siemens scanners. This proved that the corrected DESS method set in place during this PhD can be used on images obtained from different scanners, and different magnetic fields.Despite these improvements, the brain T2 values remained short compared to a Spin-Echo sequence. To investigate this issue, several simulations were performed and highlighted the influence of B0 variations in the T2 errors, as well as the high sensitivity to short T2 components. To correct the measurements, a dictionary taking into account multiple B0 variations was created. This will be useful in the case where the DESS sequence is applied on a moving organ like the liver.Also, as additional sequences have to be inserted into the protocol to correct the T2 measurements, a simultaneous T1 and T2 estimation was investigated. To reach this goal, the gradient echo trains within the MP2RAGE sequence were replaced by DESS trains. Sequence parameter optimization was explored via the Cramer Rao Lower Bound method so as to obtain both accurate T1 and T2 maps.In conclusion, through the implementation of a self-gating module, a spiral Cartesian encoding and a Compressed-Sensing acceleration, the new DESS sequence allows a rapid and repeatable estimation of T2 in the whole brain in 3D at multiple magnetic fields.Further improvements are needed to improve the T2 accuracy, and to simultaneously measure multiple quantitative parameters though the application of one sequence
Van, de moortele Pierre-françois. "Irm fonctionnelle cérébrale à 3 Tesla : développements méthodologiques." Paris 11, 1999. http://www.theses.fr/1999PA11T018.
The aim of this work is to optimize functional studies of the human brain on a whole body 3 Tesla MRI scanner. A number of artifacts were to be fixed, mainly related to the Echo Planar Imaging sequence, which affords extremely fast acquisition rates, but is highly sensitive to strong artifacts (distortion, ghost image) and produces a high level of noise. These effects are even worsened at high magnetic field values. We proposed, validated and implemented sorne original methodological approaches to attenuate some artifacts and improve the quality of fMRI studies conducted in the laboratory. We have implemented a correction procedure for image distortions (from P. Jezzard) that we have validated on cerebral activation measurements. To suppress the ghost image, which is characteristic of Echo Planar Imaging, we modified a double sampling technique (from Yang), for continuous phase encoding Echo Planar Imaging, and we wrote a specifie algorithm needed for image reconstruction. To present auditory stimuli in the context of the high level of noise, we designed two modified Echo Planar sequences with the insertion of silent periods to present verbal material to the subject. One sequence is dedicated for blocked design experiments, the other for event-elated paradigms. The modified sequences were also validated in phantom studies. After having shown that sarnpling the brain slice by slice over time produced significant bias in images analysis, we have developed and implemented a correction algorithm to interpolate samples on the first slice acquisition time for each brain volume. Head motions are one of the main sources of unsuccessful fMRI studies. To measure the head position in the magnet, we demonstrate the feasibility of a method based on non proton fiducial markers, the position of which is measured by projections interleaved in the Echo Planat imaging scheme
Chételat, Gaël. "Maladie d'Alzheimer au stade pré-démentiel : neuropsychologie et imagerie cérébrale." Lyon 1, 2002. http://www.theses.fr/2002LYO1T084.
Henry, Axelle. "Vectorisation cérébrale de deux radiotraceurs d’intérêts pour l’imagerie, la m-iodobenzylguanidine (MIBG) et la 3’-désoxy-3’- fluoro-L-thymidine (FLT)." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0019.
This research work focuses on targeting MIBG or FLT to the central nervous system. The synthesis of 1,4-dihydroquinoline carriers was first carried out in a non-radioactive manner. Previous results led us to consider the use of a linker to connect MIBG to the carrier. Regarding FLT, we focused our interest in the development of a carrier system connected directly to FLT via an ester function. For modulating the redox properties of our delivery systems, we synthesized 1,4-dihydroquinolines having electron-donating or electron-withdrawing groups at position 6 and/or 7. A study in acetonitrile/PBS buffer to determine the influence of these groups on the release of FLT was performed by HPLC. The radiosynthesis of these targeting systems was then conducted to evaluate the ability of 1,4- dihydroquinolines to deliver MIBG or FLT across the blood brain barrier (BBB). Thus, using carbon-11, we radiolabeled the delivery systems to validate the BBB crossing. Small animais were used for ex vivo studies to monitor the brain penetration and the kinetics of oxidation in the brain and periphery
Jolivel, Valérie. "Contribution à l’étude des effets neuroprotecteurs du PACAP et caractérisation d’un sonde fluorescente pour mesurer l’activité caspase-3 in vivo après ischémie cérébrale." Rouen, 2009. http://www.theses.fr/2009ROUES008.
Stroke represents an important public health problem without any treatment to prevent cell loss. Pituitary adenylate cyclase-activating polypeptide (PACAP) seems to be a good therapeutic candidate because of its ability to reduce significantly infarct volume and to improve functional deficits after cerebral ischemia but the action has been mainly studied in rodents. The results of this PhD indicate that the PACAPergic system present in the brain of primates is closely related to the one found in rodents and suggest that the neuroprotective effects of the peptide might be transposed to the primate even if the therapeutic dose should be carefully chosen. Finally we have developed a probe that allowed to detect caspase-3 activity in vivo which should speed up the experiments concerning the antiapoptotic action of PACAP after a cerebral ischemia
Stitou, Youssef. "Modélisation paramètrique 3-D fondée sur la décomposition de Wold : applications au filtrage de blocs sismiques 3-D." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13296.
Xie, Lizhe. "Reconstruction 3-D des artères coronaires en imagerie rotationnelle R-X." Rennes 1, 2012. http://www.theses.fr/2012REN1S143.
This work addresses the 3-D reconstruction of coronary arteries from a limited number of projections in rotational angiography. We propose two approaches to solve the ill-posed inverse problem. The first one is formulated as a statistical reconstruction problem and uses a Maximum a Priori (MAP) algorithm, in which L0, L1 and L2 regularizations are evaluated. The second one applies an object-oriented reconstruction, introducing a morphological model of the structure to be reconstructed. It is formed by the coronary artery centerlines and contours. The inverse problem resolution leads to minimize the strain energy of the model in both space and time. Finally the initial assumption of a prior segmentation of the structures leads to a sparse reconstruction problem that allows the parameter number in the system and the search for the solution to be restricted within a subdomain of f. The accuracy and limitations of each algorithm are evaluated and compared using a dynamic heart phantom. This dynamic sequence has been built from patient data acquired on a MSCT scan. A C-arm rotational R-X coronary angiography was then simulated using the Siemens Axiom System imaging protocol to build a sequence of 80 grey level projections
Kherif, Ferath. "Applications de modèles statistiques multivariés à la résolution de problèmes posés par les données d' imagerie fonctionnelle cérébrale." Paris 6, 2003. http://www.theses.fr/2003PA066598.
Rabut, Claire. "Neuroimagerie fonctionnelle ultrasonore 4D et connectivité fonctionnelle cérébrale chez l’animal éveillé." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS328.
This thesis focuses on the application of functional ultrasound imaging for new pre-clinical imaging modalities in rodents. Functional Ultrasound imaging (fUS) is a brain imaging modality based on Doppler imaging which makes possible to image the cerebral vascular activity with a very good sensitivity. As a first step, a new acquisition device was developed to allow transcranial functional imaging in awake, freely moving mice. We applied this device to measure the alteration of functional connectivity induced by a drug model of Alzheimer's disease. The pharmacodynamic study in awake mice allowed us to measure stable and dose dependent alterations in functional connectivity. The study was validated by a classifier automating the distinction of the pathological states using supervised learning. Using a new type of ultrasound scanner, we have also expanded the field of view of fUS imaging to the third dimension. The implemented technology has extended fUS acquisition capabilities to 4D functional. High quality films of the volume cerebral blood dynamics were obtained in rats and showed the feasibility of 4D fUS technology through different functional measurement applications. Finally, we applied the method of supersonic shear wave elastography to the evaluation of the stiffness of functional areas in the brain. We were able to monitor the brain activity by tracking changes in blood volume and at the same time generating shear waves to determine the stiffness of activated functional regions following external stimulations. The work carried out in this thesis has expanded the perspectives of pre-clinical ultrasound functional imaging for neuroscience research
Rauchs, Géraldine. "Sommeil et consolidation mnésique chez le sujet sain et dans la maladie d'Alzheimer : neuropsychologie cognitive et imagerie cérébrale." Caen, 2004. http://www.theses.fr/2004CAEN1406.
Friedrich, Corentin. "Méthodes de reconstruction en tomographie de diffraction 3-D." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0013.
This thesis is focused on microwave tomography. This imaging technique consists in estimating a three-dimensional mapping of the dielectric properties of an unknown volume from measurements of the electromagnetic field from a known incident wave and scattered by this volume. This is a promising technique that is used in various applications (medical imaging, geophysics, non- destructive testing,...) but suffers from high computational costs. This is a reason why microwave imaging is not widely used in industry. Microwave imaging is considered as an inverse problem, where the error between the measurements and a forward model that describes the scattered field is minimized as a function of the properties of the volume. This inverse problem is ill-posed because the number of unknowns is higher than the number of measurements. It is tackled through the minimization of a regularized least-squares cost function, which is addressed by local iterative optimization algorithms. Moreover, the forward model is non-linear. Thus,reconstruction is a difficult and expensive procedure. The computation of the objective function and its gradient requires the resolution of a high number of linear systems, which are performed at each iteration of the optimization algorithm and represent most of the computational cost. In this thesis, we propose to reduce the computational costs of the reconstruction algorithms by focusing on the resolution of these linear systems. Two contributions are presented. The first one is a procedure in order to reduce the number of linear systems depending on the configuration of the measurement setup. The second contribution offers an efficient way to speed up the resolutions of the systems. We adapt block resolution algorithms, in order to jointly solve multiple linear systems involving a common operator matrix. These methods are validated on simulated, realistic, 3D problems, and applied to the reconstruction of real objects from experimental measurements of scattered fields. satisfactory results are obtained, where the computation time can be reduced by a factor of two, in particular for the most difficult reconstruction problems
Bibin, Lazar. "Simulation 3-D d'anesthésie loco-régionale : neurostimulation et échographie." Paris 5, 2007. http://www.theses.fr/2007PA05S004.
Chevalier, Antoine. "Imagerie 2-D/3-D de la teneur en eau en milieu hétérogène par méthode RMP : biais et incertitudes." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU017/document.
The non-destructive observation of the ground water content's variaiblity in time and space is a major issue to understand the hydrodynamical functioning of heterogeneous media.Although many geophysical methods derive the water content of the subsurface from intermediate physical parameters, the method of surface nuclear magnetic resonance (SNMR) provide a direct estimate of ground water content. For this method, 2-D or 3-D SNMR tomography applications are only emerging and an in-depth analysis is required to assess their possibilities and limitations.The general resolution of the method is limited because the measurement characterize an important volume and is contaminated by electromagnetic noise. Consequently, the translation of measurement into an image of water content admit many solutions. Among them, several are more desirable than others from a structural/geometrical stand point. Geometrical prior knowledge are used to limit the infinite solution space. The resulting water content estimate is necessarily biased (prior knowledge) and affected by uncertainties (noise). To date, those aspects have never been quantified for 2-D and 3-D SNMR data sets.The processes that are controlling the geometrical rendering and the estimated water volume, properties of the SNMR imaging problem are analyzed using correlations and linear regressions as they are unbiased tools for the data space analysis.As the MRS inverse problem is non-linear, this thesis proposes a monte carlo based methodology (Metropolis- Hastings) to provide water content and uncertainty estimates. As the geometrical prior expectations control the estimates, the resulting bias is explored and discussed for different water content configuration.Finally, the possibilities of MRS imaging are illustrated by means of two highly heterogeneous environments: thermo-karstic and karstic. The results of the MRS imagery are compared and validated with other types of knowledge. The first case is a 2-D imaging of the conduit Poumeyssens karst. The latter geometry is precisely known. The second case is the 3-D imaging of a internal cavity inside the french alp glacier Tete-Rousse, explored by multiple other destructive and non-destructive methods
Augereau, Jean. "Techniques d'analyse par imagerie acoustique 3 D : utilisation du traitement du signal par ondelettes de Morlet." Bordeaux 1, 2008. http://www.theses.fr/2008BOR13582.
Corlier, Fabian. "Étude de l’imagerie amyloïde cérébrale et de l’élargissement des endosomes dans les cellules sanguines au cours de la maladie d’Alzheimer." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066687/document.
Alzheimer’s disease (AD) diagnostic is based on clinical and biological criteria, and is dependent on impairment of the episodic memory together with a marker of the underlying pathophysiologic process. One of the earliest events in AD pathology in the brain is formation of Amyloid deposits in the extracellular space. One of the main subcellular sites of amyloid-β (Aβ) production from amyloid precursor protein (APP) processing is the endosomal compartment. Appearance of endosomal abnormalities precede the formation of amyloid deposits, in the brain areas affected by disease progression in AD. In the present work we first studied brain amyloid load in patients with posterior cortical atrophy using [11C]PiB ligand retention in positron emitting tomography (PET). In a second part we studied the endosomal compartment in peripheral cells (fibroblasts and mononuclear leucocytes, PBMC) from AD patients, and in lymphoblastoid cell lines (LCL) from Down’s syndrome (DS) individuals where a third copy of amyloid-precursor-protein-coding gene located on chromosome 21 is known to initiate early Alzheimer’s pathology in most DS individuals. Our work shows similar profiles in topography and intensity of [PiB] binding in AD and posterior cortical atrophy (PCA), confirming underlying AD pathology in atypical focal presentations of AD. Analysis of endosomes yielded a significant increase in the frequency of cells with large endosomes in all analyzed cell types, and mean endosome volume correlated to [PiB] binding in PBMC. This result indicates that modifications of the endosomal compartment are seen in the periphery of central nervous system and may represent diagnostic tool from blood
Mellerio, Charles. "Optimisation des techniques avancées en IRM cérébrale dans la détection des lésions développementales épileptogènes." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05T025/document.
Focal cortical dysplasia type 2 (FCD2) is a common cause of intractable partial epilepsy surgically treatable. Their detection by MRI is an independent factor of good prognosis. The MR imaging diagnosis remains difficult with up to 40% negative MRI. Our main objective is to improve the detection of FCD2from conventional sequences, to assess the relevance of increased magnetic field and validate new tools for detection, in particular by identifying sulcal abnormalities associated with FCD2 automatically and visually. This study was carried out from one of the largest cohort of patients (> 80 patients) with histologically proven FCD2. The evaluation of the frequency of each MR signs showed that, although no abnormality is seen in 41% of cases, the different signs in patients with a positive MRI were never isolated and the combination of the 3 most suggestive signs of FCD2 (cortical thickening, bluring of the gray-white matter interface and "transmantle sign") was found in 27 patients (64%), indicating that MRI can be very suggestive. By increasing the magnetic field from 1.5 to 3T MRI detection rate is only slightly changed but characterization of FCD2 is improved thanks to a better visualization of the " transmantle sign " considered as a MR signature of FCD2. The automated sulcus analysis based on the calculation of a new parameter called "sulcal energy" identifies abnormal sulcal patterns in patients with FCD2 in the central region in comparison to healthy subjects. This result underlines the importance of the identification of sulci and could provide an additional criterion for detecting and locating the lesion in patients with negative MRI. Finally, the visual analysis of sulci by 3D reformatting of the cortex allowed us to describe a new MR sign of FCD2 in the central region: a sulcal pattern called the "Power Button Sign". Given its excellent reproducibility and specificity, it could be used as a new major diagnostic criterion of FCD2 in the central region. All these results contribute to the better understanding of the developmental processes involved in the pathophysiology of FCD2 and offers many opportunities for improving their MR detection
Verclytte, Sébastien. "Optimisation et évaluation de la perfusion cérébrale par technique de marquage de spin dans la Maladie d'Alzheimer à début précoce." Thesis, Lille 2, 2015. http://www.theses.fr/2015LIL2S029/document.
The diagnosis of Alzheimer's disease (AD) in patients under the age of 65 years, called early-onset Alzheimer's disease (EOAD), remains a challenging issue due to the high incidence of atypical clinical presentations with non-memory symptoms. Although EAOD has been widely explored by structural and functional imaging, no previous study has examined the contribution of ASL in the assessment of cortical perfusion in this disease. Indeed, the analysis of ASL remains complex, especially at the individual level, due to the weak signal-to-noise ratio of the perfusion maps and the heterogeneity of pathological areas in the initial phase of the disease. Our first objective was technical and has consisted in optimizing the visual interpretation of ASL maps by the cortical surface-based projection of the perfusion alterations on the structural T1 sequence acquired during the same imaging protocol, providing a 3D interactive display of the perfusion data. Data processing included several successive steps, such as a partial volume effect correction, a specific intensity normalization and a surface-based smoothing process. It was applied on the perfusion maps of eighteen EOAD patients and the quality of segmentation and of cortical surface-based perfusion maps were scored as optimal in 72% in both cases by two readers. Our second objective was clinical and aimed to characterize the cerebral hypoperfusion and hypometabolism by ASL and 18F-FDG-PET in a group of 37 EOAD patients. Our preliminary study showed: (i) a similar pathological pattern located in the inferior parietal lobules and in the temporal cortex, (ii) discrepancies between the two modalities with the presence of more widespread hypometabolic regions detected by 18F-FDGPET and additionnai areas of alterations in the frontal lobes detected by ASL without apparent hypometabolism. Our studies suggest that ASL may become a useful complementary tool which, in combination with the existing structural and functional techniques, could offer improved efficiency in the difficult early detection of EOAD and AD. Its use in clinical practice, however, requires an optimization of its visual representation, and the cortical surface-based projection applied in this work represents one of the potential ways to this image quality improvement
Pariente, Jérémie. "Neuro-imagerie fonctionnelle, deux applications : récupération motrice après un AVC, déclin cognitif dans la maladie d'Alzheimer." Toulouse 3, 2004. http://www.theses.fr/2004TOU30180.
The aim of this work was to determine to which extent the cortical network activated during an activation paradigm was altered by serotonin reuptake inhibitor after a stroke or at an early stage of Alzheimer disease. We have shown in a double blinded placebo fMRI study that SSRIs -fluoxetine and paroxetine- were able to modulate both motricity and the motor cortical network in healthy volunteers and stroke patients. We have also investigated the neuronal substrate of the placebo effect -anterior cingulum, DLPFC and opioid system- in a PET study involving patients suffering of a chronic painful condition. Finally, we have compared in an event related fMRI study Alzheimer disease patients and matched controls while performing a paired associative learning task. We have shown that patients hyperactivated a cortical network in order to compensate for the cognitive decline
Paradiso, Vincenzo. "Development of a portable gamma camera for accurate 3-D localization of radioactive hotspots." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC209.
A coded aperture gamma camera for retrieving the three-dimensional (3-D) position of radioactive sources is presented. This is of considerable interest for a wide number of applications, ranging from the reconstruction of the 3-D shape of radioactive objects to augmented reality systems. Current portable γ-cameras only provide the relative angular position of the hotspots within their field of view. That is, they do not provide any metric information concerning the located sources. In this study, we propose two approaches to estimate the distance of the surrounding hotspots, and to autonomously determine if they are occluded by an object. The first consists in combining and accurately calibrating the gamma camera with a structured-light depth sensor. The second approach allows the estimation of the source-detector distance by means of stereo gamma imaging. To geometrically align the images obtained by the gamma, depth, and optical cameras used, a versatile calibration procedure has been designed and carried out. Such procedure uses a calibration phantom intentionally easy to build and inexpensive, allowing the procedure to be performed with only one radioactive point source. Experimental results showed that our calibration procedure yields to sub-pixel accuracy both in the re-projection error and the overlay of radiation and optical images. A quantitative analysis concerning the accuracy and resolution of the retrieved source-detector distance is also provided, along with an insight into the respective most influential factors. Moreover, the results obtained validated the choice of the geometry of the pinhole model for a coded aperture gamma camera
Joos, Philippe. "Imagerie ultrasonore ultra-rapide dédiée à la quantification 3D du mouvement cardiaque." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1312/document.
This PhD work focuses on the development and the evaluation of imaging techniques in echocardiography. Our objective is to propose ultrafast ultrasound imaging methods for 2-D and 3-D cardiac motion estimations.Echocardiography is one of the most widespread modality for cardiovascular imaging. Conventional clinical scanners allow measurement of myocardial velocities and deformations at 80 images / s. In some situations, it can be recommended to increase the heart rate during a stress echocardiographic examination. Motion estimation of the whole myocardium at such heart rates is challenging with the conventional imaging systems. In addition, the low temporal resolution of the current conventional 3-D echocardiography limits quantitative applications, which would be needed for a complete characterization of the heart.The three contributions presented here are 1) the development and evaluation of an original method for 2-D cardiac motion estimation, with ultrafast imaging and image tagging, 2) the feasibility study of the global myocardial deformation measurement using an innovative 2-D ultrafast ultrasound imaging method and 3) the generalization of this approach in three dimensions for high frame-rate 3-D echocardiography. This method is based on the transmission of divergent waves and the integration of motion compensation, during the imaging process, to produce high-quality volumetric images of the heart.The proposed method allows 2-D cardiac motion estimation and 3-D echocardiography at high frame-rate. The evaluation of our approach for local 2-D and 3-D myocardial deformation measurements should permit to conduct further study in order to improve medical diagnosis
Nguyen, Ngoc Truong Huy. "Caractérisation d'un couvert forestier par un modèle cohérent 3-D dans les bandes VHF et UHF et application au traitement SAR." Paris 6, 2006. http://www.theses.fr/2006PA066072.
Boukerbout, Hassina. "Analyse en ondelettes et prolongement des champs de potentiel. Développement d'une théorie 3-D et application en géophysique." Rennes 1, 2004. http://www.theses.fr/2004REN10095.
Gu, Jia. "Mise en correspondance spatio-temporelle par chaînes attribuées et splines plaques minces pour la reconstruction 3-D des coronaires en imagerie R-X." Rennes 1, 2005. http://www.theses.fr/2005REN1S189.
We have proposed a method to improve the 3-D reconstruction of the coronary in a sequence of bi-plane angiograms. This method allows reconstituting high level structural entities from a preliminary low level segmentation by means of a matching technique (such as ASM and TPS-based registration) and perceptual grouping rules (directional continuity, colinearity, proximity, shape similarity, …). A temporal matching aimed to take advantage of the heart-induced motion to remove ambiguities related to the superposition or crossing of the structures. The missing parts of the branches were then assessed through a feedback to the original image. The centerline and contour completion were undertaken using a minimal path technique between disconnected components. It made use of a dynamic programming algorithm associated with a likelihood measure that relied on both geometric and intensity features
Aboudourib, Abderrahmane. "Imagerie en champ proche de systèmes racinaires par radar à pénétration de sol." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST048.
The mapping of tree root systems within inhomogeneous dispersive subsoils is investigated by means of a non-destructive technique: Ground-Penetrating Radar (GPR). This work is motivated by the growing need for tree health and stability control, as well as the negative impact of roots on urban infrastructure, which could seriously compromise the safety of people and properties. A state of the art has allowed us to determine the limiting factors of coarse root (diameter > 0.5 cm) detection and resolution by GPR. Then, the focus is put on a novel processing procedure to reconstruct 3-D root architectures from GPR data with no a priori information on the soils involved. Viability is studied from comprehensive numerical simulations (via gprMax) on realistic root models in 3-D heterogeneous dispersive environments; this in particular means a number of simulations involving a variety of soils. Controlled laboratory measurements are conducted on root prototypes using a bi-static GPR system operating at 300 MHz – 3.3 GHz frequency range. This is extended to field studies on real root systems with the use of a commercial GPR (MALA). The good performance and high potential of the proposed approach are illustrated accordingly
Maurice, Xavier. "Lumière structurée codée pour une reconstruction 3-D robuste : Application à la chirurgie mini-invasive." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/MAURICE_Xavier_2011.pdf.
During a minimally-invasive surgical intervention, the intra-abdominal scene, which is acquired by an endoscope, is presented to the surgeon by means of a 2-D display. The real-time depth map computation of such a scene could have huge benefits like a better visual perception, robot visual servoing, registration of pre-existing models of organs. To this end, in this thesis, many contributions leading to the realisation of an endoscopic stereo, mono-trocar, system, based on a coded structured light pattern projection, are presented. We propose to better exploit the epipolar geometry of the system at the pattern design step, first for the numerical coding, and then, for the pattern layout. Other contributions dealing with "brute-force" coding algorithm with redundancy, with real-time GPU processing, with 3-D reconstruction and with weak-calibration of the system, are described. In particular, the two main issues in "brute-force" coding algorithms : the search behaviour and the unicity test, are addressed. Moreover, an a priori compensation of optical distorsions of the projector is proposed after the pattern alignment on the epipolar geometry. Numerous coding results, ex vivo and in vivo 3-D reconstruction with associated statistics, are reported to evaluate the proposed approach
Boukerbout, Hassina. "Analyse en ondelettes et prolongement des champs de potentiel : développement d'une théorie 3-D et application en géophysique /." Rennes : Géosciences-Rennes, 2004. http://catalogue.bnf.fr/ark:/12148/cb39995468z.
Gallezot, Jean-Dominique. "Quantification in vivo des récepteurs nicotiniques à l' acétylcholine cerébraux par tomographie d'émission de position." Paris 6, 2006. http://www.theses.fr/2006PA066034.
Querbes, Olivier. "Mesure de l'épaisseur corticale en IRM : application au diagnostic précoce individuel de la maladie d'Alzheimer et à la notion de réserve cognitive." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/1597/.
Brain atrophy measured by magnetic resonance structural imaging has been proposed as a surrogate marker for the early diagnosis of Alzheimer's disease. Studies on large samples are still required to determine its practical interest at the individual level, especially with regards to the capacity of anatomical magnetic resonance imaging to disentangle the confounding role of the cognitive reserve in the early diagnosis of Alzheimer's disease. One hundred and thirty healthy controls, 122 subjects with mild cognitive impairment of the amnestic type and 130 Alzheimer's disease patients were included from the ADNI database and followed up for 24 months. After 24 months, 72 amnestic mild cognitive impairment had converted to Alzheimer's disease (referred to as progressive mild cognitive impairment, as opposed to stable mild cognitive impairment). For each subject, cortical thickness was measured on the baseline magnetic resonance imaging volume. The resulting cortical thickness map was parcellated into 22 regions and a normalized thickness index was computed using the subset of regions (right medial temporal, left lateral temporal, right posterior cingulate) that optimally distinguished stable mild cognitive impairment from progressive mild cognitive impairment. We tested the ability of baseline normalized thickness index to predict evolution from amnestic mild cognitive impairment to Alzheimer's disease and compared it to the predictive values of the main cognitive scores at baseline. In addition, we studied the relationship between the normalized thickness index, the education level and the timeline of conversion to Alzheimer's disease. Normalized thickness index at baseline differed significantly among all the four diagnosis groups (P_0. 001) and correctly distinguished Alzheimer's disease patients from healthy controls with an 85% cross-validated accuracy. Normalized thickness index also correctly predicted evolution to Alzheimer's disease for 76% of amnestic mild cognitive impairment subjects after cross-validation, thus showing an advantage over cognitive scores (range 63-72%). Moreover, progressive mild cognitive impairment subjects, who converted later than 1 year after baseline, showed a significantly higher education level than those who converted earlier than 1 year after baseline. Using a normalized thickness index-based criterion may help with early diagnosis of Alzheimer's disease at the individual level, especially for highly educated subjects, up to 24 months before clinical criteria for Alzheimer's disease diagnosis are met
Poupeau, Benoît. "Analyse et requêtes de données géographiques 3 D : contributions de la cristallographie géométrique." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00481924.
Sfikas, Giorgos. "Modèles statistiques non linéaires pour l'analyse de formes : application à l'imagerie cérébrale." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00789793.
Degiorgis, Laetitia. "Analyse des réseaux cérébraux par IRM chez un modèle souris de la maladie d’Alzheimer." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD025.
Alzheimer’s disease (AD) is the most widespread dementia in the world, presenting progressive memory impairment. Using resting-state MRI, in both human and animal studies, has opened a new window into the brain and its connectome, proposing abnormal functional connectivity as a candidate biomarker of brain pathologies such as AD. We investigated the connectome’s affectation over time in vivo in a longitudinal study, to follow-up and characterize a transgenic mouse model of AD, combining both functional and structural approaches and evaluating possible network signatures of pathological states. We associate behavioral assessment and histological staining of neurotoxic protein to the MRI approach, in order to relate pathological mechanism, at both network and cellular level, to memory dysfunction. We found remarkable structural and functional modifications, mediating prodromal alterations of the memory system, before the beginning of memory impairment. Considerable changes in the septal connectivity particularly towards limbic centers but also involving communication with the Default Mode Network were highlighted over time. These vulnerable circuits represent biomarkers of the disease and potential targets for future treatment
Hur, Justine. "Effets des acides gras ω-3 sur l'inflammation cérébro-vasculaire associée à la maladie d'Alzheimer et aux angiopathies amyloïdes cérébrales." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066384/document.
Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA) are characterized by Amyloid β-peptides depositions in the brain and cerebral vasculature respectively. Because DHA-diet is associated with a reduced risk of AD, the main objective of my thesis was to evaluate the impact of a DHA-diet on cerebrovascular and peripheral inflammation and its consequences on parenchymal and vascular Aβ-deposits during aging in a transgenic mouse model of AD/CAA (Tg2576). The Aβ-peptide deposits were detected using an anti-Aβ peptides and hemorrhages were detected with Prussian Blue on brain sections. At 10, 14 and 18 month-old, we demonstrated a reduction of amyloid vascular deposits and hemorrhages under DHA-diet compared to placebo, while parenchymal Aβ-peptides deposits remain unaffected. Moreover, we demonstrated a strong negative correlation between amyloid vascular deposition, hemorrhage and a lipid-derived pro-inflammatory mediator, 12-HETE. We next evaluated the in vitro effects of Aβ1-40-peptide on 12-HETE production by the Vascular Smooth Muscle Cells. We demonstrated that the mRNA level of the 12-LOX enzyme, involved in 12-HETE synthesis, was increased when cells where incubated with Aβ1-40-peptide, suggesting a cause-to-effect relationship between Aβ deposits and pro-inflammatory biolipids. The work carried out during my thesis made it possible to demonstrate DHA protective effect on evolution and consequences of Aβ peptide cerebrovascular accumulation and link it to plasma 12-HETE level. My work emphasized once again the importance of inflammation in AAC pathogenesis while opening up a new pathway for potential targets in the preventive intervention of this pathology
Oksenhendler, Vincent. "Développement d'un système opto-électronique de vision 3-D pour l'établissement en temps réel de cartes de distances." Rouen, 1997. http://www.theses.fr/1997ROUES047.
Martin, Emmanuel. "Dart : modèle 3D multispectral et inversion d’images optique de satellite : application aux couverts forestiers." Toulouse 3, 2006. http://www.theses.fr/2006TOU30269.
In optical remote sensing, radiative transfer (R-T) models aim to simulate radiometric measurement of spatial sensors that spot “Landscape-Atmosphere” system. The modeling of vegetation canopies measurements is generally limited to landscape representation and R-T modeling. This thesis allowed transforming a 3-D R-T model DART (patent : PCT/FR 02/01181) to multispectral model simulating optical remote sensing images (thermal infrared included) of any natural and urban landscape with relief and atmosphere for any spatial/airborne sensor. This new model was validated by models intercomparison (RAMI-3 experience, Joint Research Centre, Italy) and with in situ and airborne measurements (Czech Republic). In fine, an inversion method was developed. It allowed using DART for evaluating the modeling impact on LAI estimation of coniferous forest using hyperspectral VHR images
Guillon, Jérémy. "Multilayer Approach to Brain Connectivity in Alzheimer’s Disease." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS305.
Alzheimer’s disease causes alterations of the brain networks structure and function that can be modelized by a brain connectivity analyse. We proposed a multi-layer approach to analyse multi-frequency and multimodal brain networks built from magnetoencephalographic (MEG) recordings, functional (fMRI) or diffusion-weighted magnetic resonance imaging (DWI). Main results showed the existence of previously undefined type of hubs that are inter-frequency hubs; identified thanks to their multi-participation coefficient (MPC) computed from a brain connectivity network with a multi-frequency multiplex topology. These hubs are impacted by Alzheimer’s disease, which reduces their naturally high ability to integrate information propagating through different frequency bands. We also generalized the concept of core-periphery structure to multilayer networks to be able to apply it to a multimodal brain connectivity model that combines structural and functional networks in a single multiplex topology. Hence, we could identify, from a systemic point of view, the most important regions at the scale of the entire brain and study their alteration in patients with Alzheimer’s disease. Therefore, this thesis expose how multilayer networks applied to brain connectivity can help in understanding neurodegenerative diseases such as Alzheimer’s disease
Ternifi, Redouane. "Mesure de la pulsatilité naturelle du tissu cérébral par ultrasons." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR3306/document.
The 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
Yaacoub, Fadi. "Development of virtual reality tools for arthroscopic surgery training." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00481944.
Bouënard, Alexandre. "Synthesis of Music Performances: Virtual Character Animation as a Controller of Sound Synthesis." Phd thesis, Université de Bretagne Sud, 2009. http://tel.archives-ouvertes.fr/tel-00497292.
Bousse, Alexandre. "Problèmes inverses, application à la reconstruction compensée en mouvement en angiographie rotationnelle X." Phd thesis, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00361396.
Une fois le mouvement estimé, la reconstruction tomographique à un instant de référence est effectuée par une optimisation aux moindres-carrés qui inclut le mouvement ainsi qu'un terme de pénalité qui favorise les valeurs d'intensités fortes pour les voxels au voisinage de la ligne centrale 3-D, et les faibles valeurs pour les autres. Cette méthode a été testée sur des données simulées basées sur des lignes centrales 3-D préalablement extraites de données MSCT.
Huang, Di. "Robust face recognition based on three dimensional data." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00693158.
Viswanathan, Kartik. "Représentation reconstruction adaptative des hologrammes numériques." Thesis, Rennes, INSA, 2016. http://www.theses.fr/2016ISAR0012/document.
With the increased interest in 3D video technologies for commercial purposes, there is renewed interest in holography for providing true, life-like images. Mainly for the hologram's capability to reconstruct all the parallaxes that are needed for a truly immersive views that can be observed by anyone (human, machine or animal). But the large amount of information that is contained in a hologram make it quite unsuitable to be transmitted over existing networks in real-time. In this thesis we present techniques to effectively reduce the size of the hologram by pruning portions of the hologram based on the position of the observer. A large amount of information contained in the hologram is not used if the number of observers of an immersive scene is limited. Under this assumption, parts of the hologram can be pruned out and only the requisite parts that can cause diffraction at an observer point can be retained. For reconstructions these pruned holograms can be propagated numerically or optically. Wavelet transforms are employed to capture the localized frequency information from the hologram. The selection of the wavelets is based on the localization capabilities in the space and frequency domains. Gabor and Morlet wavelets possess good localization in space and frequency and form good candidates for the view based reconstruction system. Shannon wavelets are also employed for this cause and the frequency domain based application using the Shannon wavelet is shown to provide fast calculations for real-time pruning and reconstruction
Dupont, Erwan. "Méthode de mesure tridimensionnelle active appliquée au contexte de l’analyse endoscopique ou coloscopique." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2198/document.
This thesis aims at developing a tri-dimensional measurement endoscopic device in a double context: the first one is industrial with endoscopic inspection of mechanical pieces (tubular inspection, for example) at micrometric resolution. The second context is medical with tri-dimensional shape detection during colonoscopy to help the surgeon diagnosis. In this study, flexible endoscopy is made possible by using image guides and the tri-dimensional reconstruction method is based on active stereovision where a digital micro-mirror device is used to spatially structure the incoming light. After developing the state of the art, an optical conception and evaluation method, applied to stereovision for flexible endoscopic devices is described. The instrumental realization is then detailed and metrologically evaluated. An innovative method that allows to switch dynamically between active and passive stereovision is then detailed. Finally, 3D reconstruction algorithms adapted to this endoscopic instrument are proposed. The scientific contributions of this study are multiple. Firstly, an optical analysis method based on the modulation transfer function to design an endoscopic stereovision system is proposed. An image processing method for robust calibration in a defocused optical environment and a new phase-shifting algorithm for 3D reconstruction are proposed. Finally, a realization principle for 3D measurement in flexible endoscopy was extracted from the combination of all these methods
Hou, Yingfan. "Apport de la combinaison de méthodes de mesure de formes tridimensionnelles dans le contexte de l'endoscopie flexible." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2255/document.
The techniques of three dimensional shapes reconstruction are widely used in many fields, particularly in the industrial or medical field. And in these areas, non-contact measurement techniques are particularly studied, mainly because they don't damage the measured object. This work therefore falls within this context and in particular in the case of endoscopic devices of surface coordinate measuring by optical methods. ln the medical field, this type of instrument can be applied to 3D colonoscopy or minimally invasive surgery to the surface in the form of biological tissues. In this thesis, methods based on active or passive stereo vision are the principle, which will be studied and integrated into a miniaturized device. Different measurement modes will be incorporated simultaneously into a single miniaturized instrument to help increase measurement performance: the instrument can adjust its measurement principle to the texture of the object or also to the orientation of measured surfaces more generally to the context of the measurement. This thesis is based on an algorithmic study and instrumental integration of these different measurement modes into a single miniaturized endoscopic instrument. The study of the measurement modes stereovision was conducted in three phases. First, it is the influence of the orientation of the measured objects' surface in a case of active stereovision being analyzed. And a technique of switching between the projection and acquisition in an active stereovision system by bistable actuation is proposed, which allows to adapt the measurement to the orientation of the measured surfaces. Finally, the study is oriented towards the ability to switch from one active stereovision mode to one passive stereovision mode, always by bistable actuator operation, the passive stereovision mode is particularly suitable for highly textured objects. Thus, three measurement modes are made in the new system: two modes of active stereovision (reversing capture and projection channels) and a mode of passive stereovision. To achieve three-dimensional reconstruction, two active methods (phase shift and Fourier Transform) and a passive method are studied. Different performance measurements are obtained according to methods selected: a more accurate measuring result is obtained by the phase shift methods; a high measurement speed is obtained by the Fourier transform methods or by passive methods. The instrumental development is also described in this thesis. After optical modeling and mechanical design of the measuring system, a prototype of the endoscopic instrument is manufactured with various specific devices such as a DMD (Digital Micromirror Deviee),images guides and bistable electromagnetic actuators. The experimental validation of the three-dimensional measurement is performed mainly on mechanical objects (such as details measurement on a coin), both active and passive method methods are well tested and compared. Finally, an artificial colon is measured by this system to be placed in a medical application context
Simonetto, Elisabeth. "Extraction 3-D de structures industrielles sur des images RAMSES haute résolution par radargrammétrie." Phd thesis, 2002. http://tel.archives-ouvertes.fr/tel-00749513.