10 research outputs found

    Three-Dimensional Biplanar Reconstruction of the Scoliotic Spine for Standard Clinical Setup

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    Tese de Doutoramento. Engenharia Informática. Faculdade de Engenharia. Universidade do Porto. 201

    Reconstruction 3D personnalisée de la colonne vertébrale à partir d'images radiographiques non-calibrées

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    Les systèmes de reconstruction stéréo-radiographique 3D -- La colonne vertébrale -- La scoliose idiopathique adolescente -- Évolution des systèmes de reconstruction 3D -- Filtres de rehaussement d'images -- Techniques de segmentation -- Les méthodes de calibrage -- Les méthodes de reconstruction 3D -- Problématique, hypothèses, objectifs et méthode générale -- Three-dimensional reconstruction of the scoliotic spine and pelvis from uncalibrated biplanar X-ray images -- A versatile 3D reconstruction system of the spine and pelvis for clinical assessment of spinal deformities -- Simulation experiments -- Clinical validation -- A three-dimensional retrospective analysis of the evolution of spinal instrumentation for the correction of adolescent idiopathic scoliosis -- Auto-calibrage d'un système à rayons-X à partir de primitives de haut niveau -- Segmentation de la colonne vertébrale -- Approche hiérarchique d'auto-calibrage d'un système d'acquisition à rayons-X -- Personalized 3D reconstruction of the scoliotic spine from hybrid statistical and X-ray image-based models -- Validation protocol

    Investigation of 3D glenohumeral displacements from 3D reconstruction using biplane X-ray images: Accuracy and reproducibility of the technique and preliminary analysis in rotator cuff tear patients

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    Rotator cuff (RC) tears may be associated with increased glenohumeral instability; however, this instability is difficult to quantify using currently available diagnostic tools. Recently, the three-dimensional (3D) reconstruction and registration method of the scapula and humeral head, based on sequences of low-dose biplane X-ray images, has been proposed for glenohumeral displacement assessment. This research aimed to evaluate the accuracy and reproducibility of this technique and to investigate its potential with a preliminary application comparing RC tear patients and asymptomatic volunteers. Accuracy was assessed using CT scan model registration on biplane X-ray images for five cadaveric shoulder specimens and showed differences ranging from 0.6 to 1.4 mm depending on the direction of interest. Intra- and interobserver reproducibility was assessed through two operators who repeated the reconstruction of five subjects three times, allowing defining 95% confidence interval ranging from ±1.8 to ±3.6 mm. Intraclass correlation coefficient varied between 0.84 and 0.98. Comparison between RC tear patients and asymptomatic volunteers showed differences of glenohumeral displacements, especially in the superoinferior direction when shoulder was abducted at 20 and 45 . This study thus assessed the accuracy of the low-dose 3D biplane X-ray reconstruction technique for glenohumeral displacement assessment and showed potential in biomechanical and clinical research.Fondation Paris-Tech Programme BIOMECAM Chaire ParisTech Institut de Recherche Robert-Sauvé en Santé et Sécurité du Travail du Québec Natural Science and Engineering Research Council of Canada Fonds de Recherche sur la Nature et les Technologies du Québec Fonds de Recherche en Santé du Québec, EOS Imaging, and French pôle de compétitivité MEDICEN (STEREOS + program)

    Contribution à la reconstruction 3D des membres inférieurs reconstruits à partir des radios biplanes pour l'application à la planification et au suivi des chirurgies

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    Pour comprendre et diagnostiquer les pathologies qui affectent l organisation spatialede notre squelette, il est essentiel d aborder ces problématiques en 3D. Le CT-Scan et l IRMsont des modalités d imagerie couramment utilisées en milieu clinique pour étudier en 3D notresystème musculosquelettique. La plupart de ces systèmes d imagerie proposent une acquisitioncouchée sur laquelle les effets gravitaires ne sont pas pris en compte. Le CT-Scan est unemodalité particulièrement irradiante et l IRM est plus spécifiquement dédiée à l étude des tissusmous. Le système EOS permet de reconstruire en 3D les os à partir d une paire deradiographies biplanes à faible dose d irradiation. En plus, le système EOS propose uneacquisition en position debout, prenant en compte les effets gravitaires. Cette thèse contribue àl amélioration des méthodes de reconstruction 3D des membres inférieurs à partir des radiosbiplanes. Dans le cadre de thèse on a proposé et évalué : 1) Une méthode de reconstruction3D des membres inférieurs s appuyant sur des modèles paramétrés et des inférencesstatistiques. 2) Une méthode d auto-amélioration de la reconstruction 3D des membresinférieurs en utilisant du traitement d images local et le recalcul d inférences statistiques. 3)Enfin, des méthodes utilisant des critères de similarité d images et des critères morphologiquespour détecter de manière automatique le côté médial et latéral du fémur et du tibia. Le but estd éviter l inversion par l opérateur de condyles fémoraux et plateaux tibiaux, affectant la valeurdes paramètres cliniques, surtout les torsions. La méthode de reconstruction proposée dans lecadre de cette thèse est intégrée dans le logiciel sterEOS® et utilisée dans une soixantained hôpitaux au monde. Les méthodes développées dans le cadre de cette thèse ont permis deprogresser vers la reconstruction semi-automatisée, précise et robuste du membre inférieurFor a better understanding and diagnosis of the pathologies affecting the spatialorganization of our skeleton it is necessary to address them in 3D. CT-Scan and MRI areimaging modalities commonly used to study the musculoskeletal system in 3D. Moreover,patients are recorded in reclining position thus gravity effect can t be taken into account.Furthermore, CT-Scan exposes patient to high radiation doses and MRI is used mostly tocharacterize soft tissues. With the EOS system, from a pair of low dose biplanar radiographs wecan reconstruct bones in 3D, and the radiographs are recorded in standing position thus gravityeffects are considered. This thesis contributes to the improvement of the 3D reconstructionmethods of lower limbs from biplanar radiographs. In this thesis we have proposed andevaluated: 1) A 3D reconstruction method of the lower limbs based on parametric models andstatistical inferences. 2) A method for the auto-improvement of the 3D reconstruction of thelower limbs. This method combines image processing and the recalculation of the statisticalinferences. 3) Finally, methods based on similarity measures and shape criteria were used todetect automatically the medial and lateral side of the femur and tibia. The aim of thesemethods is to avoid the inversion of the femoral and tibial condyles in biplanar radiographs.These inversions have an impact in the calculation of clinical measurements, particularly thetorsional ones. The reconstruction method proposed in this thesis is already integrated withinthe sterEOS® software, available in 60 hospitals around the world. The methods developed inthis thesis have led us to a semi-automatic, accurate and robust reconstruction of lower limbs.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

    Interlandmark measurements from lodox statscan images with application to femoral neck anteversion assessment

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    Includes abstract.Includes bibliographical references.Clinicians often take measurements between anatomical landmarks on X-ray radiographs for diagnosis and treatment planning, for example in orthopaedics and orthodontics. X-ray images, however, overlap three-dimensional internal structures onto a two-dimensional plane during image formation. Depth information is therefore lost and measurements do not truly reflect spatial relationships. The main aim of this study was to develop an inter-landmark measurement tool for the Lodox Statscan digital radiography system. X-ray stereophotogrammetry was applied to Statscan images to enable three-dimensional point localization for inter-landmark measurement using two-dimensional radiographs. This technique requires images of the anatomical region of interest to be acquired from different perspectives as well as a suitable calibration tool to map image coordinates to real world coordinates. The Statscan is suited to the technique because it is capable of axial rotations for multiview imaging. Three-dimensional coordinate reconstruction and inter-landmark measurements were taken using a planar object and a dry pelvis specimen in order to assess the intra-observer measurement accuracy, reliability and precision. The system yielded average (X, Y, Z) coordinate reconstruction accuracy of (0.08 0.12 0.34) mm and resultant coordinate reconstruction accuracy within 0.4mm (range 0.3mm – 0.6mm). Inter-landmark measurements within 2mm for lengths and 1.80 for angles were obtained, with average accuracies of 0.4mm (range 0.0mm – 2.0 mm) and 0.30 (range 0.0 – 1.8)0 respectively. The results also showed excellent overall precision of (0.5mm, 0.10) and were highly reliable when all landmarks were completely visible in both images. Femoral neck anteversion measurement on Statscan images was also explored using 30 dry right adult femurs. This was done in order to assess the feasibility of the algorithm for a clinical application. For this investigation, four methods were tested to determine the optimal landmarks for measurement and the measurement process involved calculation of virtual landmarks. The method that yielded the best results produced all measurements within 10 of reference values and the measurements were highly reliable with very good precision within 0.10. The average accuracy was within 0.40 (range 0.10 –0.80).In conclusion, X-ray stereophotogrammetry enables accurate, reliable and precise inter-landmark measurements for the Lodox Statscan X-ray imaging system. The machine may therefore be used as an inter-landmark measurement tool for routine clinical applications

    3D Shape Reconstruction of Knee Bones from Low Radiation X-ray Images Using Deep Learning

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    Understanding the bone kinematics of the human knee during dynamic motions is necessary to evaluate the pathological conditions, design knee prosthesis, orthosis and surgical treatments such as knee arthroplasty. Also, knee bone kinematics is essential to assess the biofidelity of the computational models. Kinematics of the human knee has been reported in the literature either using in vitro or in vivo methodologies. In vivo methodology is widely preferred due to biomechanical accuracies. However, it is challenging to obtain the kinematic data in vivo due to limitations in existing methods. One of the several existing methods used in such application is using X-ray fluoroscopy imaging, which allows for the non-invasive quantification of bone kinematics. In the fluoroscopy imaging method, due to procedural simplicity and low radiation exposure, single-plane fluoroscopy (SF) is the preferred tool to study the in vivo kinematics of the knee joint. Evaluation of the three-dimensional (3D) kinematics from the SF imagery is possible only if prior knowledge of the shape of the knee bones is available. The standard technique for acquiring the knee shape is to either segment Magnetic Resonance (MR) images, which is expensive to procure, or Computed Tomography (CT) images, which exposes the subjects to a heavy dose of ionizing radiation. Additionally, both the segmentation procedures are time-consuming and labour-intensive. An alternative technique that is rarely used is to reconstruct the knee shape from the SF images. It is less expensive than MR imaging, exposes the subjects to relatively lower radiation than CT imaging, and since the kinematic study and the shape reconstruction could be carried out using the same device, it could save a considerable amount of time for the researchers and the subjects. However, due to low exposure levels, SF images are often characterized by a low signal-to-noise ratio, making it difficult to extract the required information to reconstruct the shape accurately. In comparison to conventional X-ray images, SF images are of lower quality and have less detail. Additionally, existing methods for reconstructing the shape of the knee remain generally inconvenient since they need a highly controlled system: images must be captured from a calibrated device, care must be taken while positioning the subject's knee in the X-ray field to ensure image consistency, and user intervention and expert knowledge is required for 3D reconstruction. In an attempt to simplify the existing process, this thesis proposes a new methodology to reconstruct the 3D shape of the knee bones from multiple uncalibrated SF images using deep learning. During the image acquisition using the SF, the subjects in this approach can freely rotate their leg (in a fully extended, knee-locked position), resulting in several images captured in arbitrary poses. Relevant features are extracted from these images using a novel feature extraction technique before feeding it to a custom-built Convolutional Neural Network (CNN). The network, without further optimization, directly outputs a meshed 3D surface model of the subject's knee joint. The whole procedure could be completed in a few minutes. The robust feature extraction technique can effectively extract relevant information from a range of image qualities. When tested on eight unseen sets of SF images with known true geometry, the network reconstructed knee shape models with a shape error (RMSE) of 1.91± 0.30 mm for the femur, 2.3± 0.36 mm for the tibia and 3.3± 0.53 mm for the patella. The error was calculated after rigidly aligning (scale, rotation, and translation) each of the reconstructed shape models with the corresponding known true geometry (obtained through MRI segmentation). Based on a previous study that examined the influence of reconstructed shape accuracy on the precision of the evaluation of tibiofemoral kinematics, the shape accuracy of the proposed methodology might be adequate to precisely track the bone kinematics, although further investigation is required

    Contribution à la modélisation géométrique et mécanique du tronc de l'enfant

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    Despite of the use of homologated Child Restraint Systems, 2,321 children were killed on European roads in 2007. This social and economical major issue is explained by the lack of biomechanical knowledge on injury mechanisms and associated physical parameters, specifically for children. The present project was supported by the GDR “Biomécanique des chocs“ (CNRS/INRETS/GIE PSA Renault) and funded by the French National Research Agency. The aim of this study is to improve the biomechanical knowledge of the children trunk. The dynamic response of the trunk is essential because it is the main segment used for the whole body restraint when a car crash occurs. In order to improve the reliability of children's models, subject-specific inertial parameters of the body segments were calculated using 3D reconstructions from low dose biplanar X-rays. The fine description of the ribs, costal cartilage and sternum was performed on 3D models from CT-scan. The 3D geometry of the intra-abdominal child organs (kidney, spleen and liver) was defined by measurements based upon 3D modeling using abdominal CT-scan. The quantification of the thoracic and abdominal behaviors was obtained in observing in vivo trunk manipulations carried out within the framework of usual physiotherapist treatments. This research will be used to improve or develop the trunk bio-fidelity of child models and constitute a first step toward an enhanced knowledge of the child biomechanics based directly on in vivo experimentation.Malgré l'obligation d'utiliser des Dispositifs de Retenue Enfant homologués, 2 321 enfants ont été tués en 2007 sur les routes européennes. Ce problème socio-économique majeur est expliqué par le manque de connaissance biomécanique de l'enfant. Le développement de modèles d'enfant nécessite la compréhension de ses paramètres biomécaniques et critères lésionnels. Ce projet, supporté par le GDR « Biomécanique des chocs » (CNRS/INRETS/GIE PSA Renault) et financé par l'Agence Nationale de la Recherche (ANR-06-BLAN-0385 SECUR_ENFANT), a pour objectif de contribuer à l'amélioration de ces connaissances, en s'intéressant particulièrement au tronc de l'enfant. La réponse mécanique de ce segment corporel est essentielle car c'est le principal composant utilisé lors de la retenue en choc automobile. Les paramètres inertiels des segments corporels ont été calculés à partir de reconstructions personnalisées 3D issues de radiographies biplanaires basse dose. La description précise des côtes, du cartilage costal et du sternum a été évaluée à partir de modélisations 3D issues de données d'imagerie scanner. Des reconstructions de reins, rates et foies à partir de scanners abdominaux ont permis de définir la géométrie et le positionnement de ces organes dans le système ostéoarticulaire. Enfin, le comportement mécanique du thorax et de l'abdomen d'enfants a été quantifié à partir de manipulations in vivo faites en routine clinique de kinésithérapie respiratoire. Les résultats de ce travail, basés sur des examens in vivo, sont utiles à l'amélioration de la biofidélité du tronc des modèles d'enfants et contribuent à l'approfondissement des connaissances biomécaniques de l'enfant

    Automated analysis and visualization of preclinical whole-body microCT data

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    In this thesis, several strategies are presented that aim to facilitate the analysis and visualization of whole-body in vivo data of small animals. Based on the particular challenges for image processing, when dealing with whole-body follow-up data, we addressed several aspects in this thesis. The developed methods are tailored to handle data of subjects with significantly varying posture and address the large tissue heterogeneity of entire animals. In addition, we aim to compensate for lacking tissue contrast by relying on approximation of organs based on an animal atlas. Beyond that, we provide a solution to automate the combination of multimodality, multidimensional data.* Advanced School for Computing and Imaging (ASCI), Delft, NL * Bontius Stichting inz Doelfonds Beeldverwerking, Leiden, NL * Caliper Life Sciences, Hopkinton, USA * Foundation Imago, Oegstgeest, NLUBL - phd migration 201

    Epidemiology of Injury in English Women's Super league Football: A Cohort Study

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    INTRODUCTION: The epidemiology of injury in male professional football has been well documented (Ekstrand, Hägglund, & Waldén, 2011) and used as a basis to understand injury trends for a number of years. The prevalence and incidence of injuries occurring in womens super league football is unknown. The aim of this study is to estimate the prevalence and incidence of injury in an English Super League Women’s Football squad. METHODS: Following ethical approval from Leeds Beckett University, players (n = 25) signed to a Women’s Super League Football club provided written informed consent to complete a self-administered injury survey. Measures of exposure, injury and performance over a 12-month period was gathered. Participants were classified as injured if they reported a football injury that required medical attention or withdrawal from participation for one day or more. Injuries were categorised as either traumatic or overuse and whether the injury was a new injury and/or re-injury of the same anatomical site RESULTS: 43 injuries, including re-injury were reported by the 25 participants providing a clinical incidence of 1.72 injuries per player. Total incidence of injury was 10.8/1000 h (95% CI: 7.5 to 14.03). Participants were at higher risk of injury during a match compared with training (32.4 (95% CI: 15.6 to 48.4) vs 8.0 (95% CI: 5.0 to 10.85)/1000 hours, p 28 days) of which there were three non-contact anterior cruciate ligament (ACL) injuries. The epidemiological incidence proportion was 0.80 (95% CI: 0.64 to 0.95) and the average probability that any player on this team will sustain at least one injury was 80.0% (95% CI: 64.3% to 95.6%) CONCLUSION: This is the first report capturing exposure and injury incidence by anatomical site from a cohort of English players and is comparable to that found in Europe (6.3/1000 h (95% CI 5.4 to 7.36) Larruskain et al 2017). The number of ACL injuries highlights a potential injury burden for a squad of this size. Multi-site prospective investigations into the incidence and prevalence of injury in women’s football are require
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