3D reconstruction of ribcage geometry from biplanar radiographs using a statistical parametric model approach

Rib cage 3D reconstruction is an important prerequisite for thoracic spine modelling, particularly for studies of the deformed thorax in adolescent idiopathic scoliosis. This study proposes a new method for rib cage 3D reconstruction from biplanar radiographs, using a statistical parametric model approach. Simplified parametric models were defined at the hierarchical levels of rib cage surface, rib midline and rib surface, and applied on a database of 86 trunks. The resulting parameter database served to statistical models learning which were used to quickly provide a first estimate of the reconstruction from identifications on both radiographs. This solution was then refined by manual adjustments in order to improve the matching between model and image. Accuracy was assessed by comparison with 29 rib cages from CT scans in terms of geometrical parameter differences and in terms of line-to-line error distance between the rib midlines. Intra and inter-observer reproducibility were determined regarding 20 scoliotic patients. The first estimate (mean reconstruction time of 2’30) was sufficient to extract the main rib cage global parameters with a 95% confidence interval lower than 7%, 8%, 2% and 4° for rib cage volume, antero-posterior and lateral maximal diameters and maximal rib hump, respectively. The mean error distance was 5.4 mm (max 35mm) down to 3.6 mm (max 24 mm) after the manual adjustment step (+3’30). The proposed method will improve developments of rib cage finite element modeling and evaluation of clinical outcomes.This work was funded by Paris Tech BiomecAM chair on subject specific muscular skeletal modeling, and we express our acknowledgments to the chair founders: Cotrel foundation, Société générale, Protéor Company and COVEA consortium. We extend your acknowledgements to Alina Badina for medical imaging data, Alexandre Journé for his advices, and Thomas Joubert for his technical support

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

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

Multimodal image fusion of anatomical structures for diagnosis, therapy planning and assistance

This paper provides an overview of work done in recent years by our research group to fuse multimodal images of the trunk of patients with Adolescent Idiopathic Scoliosis (AIS) treated at Sainte-Justine University Hospital Center (CHU). We first describe our surface acquisition system and introduce a set of clinical measurements (indices) based on the trunk's external shape, to quantify its degree of asymmetry. We then describe our 3D reconstruction system of the spine and rib cage from biplanar radiographs and present our methodology for multimodal fusion of MRI, X-ray and external surface images of the trunk We finally present a physical model of the human trunk including bone and soft tissue for the simulation of the surgical outcome on the external trunk shape in AIS.CIHR / IRS

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

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

A 3D computer assisted Orthopedic Surgery Planning approach based on planar radiography

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Informática Médica)The main goal of this work consisted in develop a system to perform the 3D reconstruction of bone models from radiographic images. This system can be then integrated with a commercial software that performs pre-operative planning of orthopedic surgeries. The benefit of performing this 3D reconstruction from planar radiography is that this modality has some advantages over other modalities that perform this reconstruction directly, like CT and MRI. To develop the system it was used radiographic images of the femur obtained from medical image databases online. It was also used a generic model of the femur available in the online repository BEL. This generic model completes the information missing in the radiographic images. It was developed two methods to perform the 3D reconstruction through the deformation of the generic model, one uses triangulation of extracted edge points and the other don't. The first method was not successful, the final model had very low thickness, possibly because the triangulation process was not performed correctly. With the second method it was obtained a 3D bone model of the femur aligned with the radiographic images of the patient and with the same size as the patient's bone. However, the obtained model still needs some adjustment to coincide fully with reality. To perform this is necessary to enhance the deformation step of the model so that it will have the same shape as the patient's bone. The second method is more advantageous because it doesn't need the parameters of the x-ray imaging system. However, it's necessary to enhance the step deformation of this method so that the final model matches patient's anatomy.O principal objetivo deste trabalho consistiu em desenvolver um sistema capaz de realizar a reconstrução 3D de modelos ósseos a partir de imagens radiográficas. Este sistema pode posteriormente ser integrado num produto comercial que realiza o planeamento pré-operativo de cirurgias ortopédicas. O benefício de realizar esta reconstrução 3D a partir de radiografias está relacionado com o facto desta modalidade ter vantagens em relação às outras modalidades que fazem esta reconstrução diretamente, como as modalidades CT e MRI. Para desenvolver este sistema foram usadas imagens radiográficas do fémur obtidas através de bases de dados online de imagens médicas. Também foi usado um modelo genérico do fémur disponível no repositório online BEL. Este modelo genérico completa a informação que está em falta nas imagens radiográficas. Foram desenvolvidos dois métodos, que realizam a reconstrução 3D através da deformação do modelo genérico sendo que num é feita a triangulação de pontos dos contornos e noutro não. O primeiro método não foi bem sucedido, visto que o modelo final tinha uma espessura muito pequena, possivelmente devido ao facto do processo de triangulação não ter sido executado corretamente. Com o segundo método foi obtido um modelo 3D do fémur alinhado com as imagens radiográficas do paciente e com o mesmo tamanho do osso do paciente. No entanto, o modelo obtido carece ainda de alguma afinação de modo a coincidir na íntegra com a realidade. Para fazer isto é necessário melhorar o passo de deformação do modelo, para que este fique com a mesma forma do osso do paciente. O segundo método é mais vantajoso porque não necessita dos parâmetros dos sistema de raios- X. No entanto, é necessário melhorar o passo de deformação deste método para que o modelo final coincida com a anatomia do paciente

Méthode de mesure automatique intraopératoire des déformations du rachis scoliotique

RÉSUMÉ La scoliose idiopathique de l'adolescence est une pathologie complexe et évolutive entraînant une déformation tridimensionnelle du rachis, de la cage thoracique et du bassin. Cette pathologie affecte 2 à 4% de la population adolescente. Dans le cas de scolioses sévères, un traitement chirurgical est recommandé. L’imagerie radiographique est la technique la plus répandue pour le diagnostic et le suivi des effets de cette pathologie. De plus, des outils de reconstruction 3D du rachis à partir de radiographies du patient sont actuellement disponibles avant la chirurgie pour permettre une caractérisation bi- et tridimensionnelle des déformations scoliotiques ainsi que la planification des manoeuvres d'instrumentation. Les modèles 3D préopératoires ne sont pas directement utilisables pendant la chirurgie puisqu'il y existe un changement des courbures scoliotiques dû à la position allongée, à l'exposition chirurgicale et à l'anesthésie. Plusieurs systèmes de suivi ont été testés pour suivre le changement de forme du rachis et le mouvement des vertèbres en intraopératoire : mécaniques, optoélectroniques, électromagnétiques, ultrasons, radiographiques. Ces systèmes permettent de détecter la position des vertèbres pendant la chirurgie et peuvent être utilisés pour la mise à jour de modèles 3D préopératoires. Pour ce faire, ils requièrent l'installation de marqueurs sur les vertèbres ou l'identification manuelle de points anatomiques pendant la chirurgie, ce qui peut interférer avec la procédure chirurgicale. Ainsi, des systèmes d'imagerie et de navigation intraopératoires sont actuellement disponibles pour visualiser les déformations 3D du rachis et guider les manoeuvres d'instrumentation de façon sûre et précise. Cependant, à partir de ces systèmes, il n'est pas encore possible de quantifier en intraopératoire les déformations scoliotiques et la correction résultant des manoeuvres d'instrumentation. Ce projet de maîtrise visait à développer une technique permettant la mesure intraopératoire automatique des déformations scoliotiques afin de fournir au chirurgien des données quantitatives exploitables pour évaluer et améliorer la stratégie chirurgicale. Globalement, le calcul des déformations scoliotiques 3D a été effectué grâce à la mise à jour d'un modèle géométrique préopératoire à partir d'images fluoroscopiques 3D intraopératoires. De façon plus précise, un modèle géométrique préopératoire a été construit à partir de 28 repères anatomiques vertébraux identifiés manuellement par un opérateur sur des radiographies biplanaires en position érigée avant la chirurgie. Ces points ont été utilisés pour obtenir un modèle----------ABSTRACT Adolescent idiopathic scoliosis (AIS) is a complex and progressive pathology leading to threedimensional deformities of the spine, rib cage and pelvis. This pathology affects 2 to 4% of the adolescent population. In the case of severe scoliosis, a surgical treatment is required. Radiographic imaging is mostly used for the diagnosis and the monitoring of scoliosis. 3D reconstruction of the spine from patient’s radiographs is currently available to enable the twoand three-dimensional characterization of scoliotic deformities and planning of the instrumentation maneuvers. The 3D preoperative models can’t be directly used during surgery since there is a change in the scoliotic curvature caused by the prone positioning, the surgical exposure and the anesthesia. Several tracking systems have been tested to monitor the spinal shape changes and follow the intraoperative motion of the vertebrae: optoelectronics or electromagnetics systems, ultrasounds, radiographs. These systems enable the tracking of the intraoperative positioning of the vertebrae, and can be used to update 3D preoperative models. This requires the installation of external markers on vertebrae or the manual identification of anatomic points during surgery, which can interfere with the surgical procedure. Imaging and navigation systems are then currently available to visualize the 3D deformities of the spine and to safely and precisely guide the instrumentation maneuvers. Nevertheless, these systems do not enable the quantification of the intraoperative scoliotic deformities and the correction resulting from instrumentation maneuvers. This project aimed to develop a technique that enables the automatic intraoperative measurement of the scoliotic deformities, in order to provide the surgeon with quantitative feedback to evaluate and improve the surgical strategy. The 3D scoliotic deformities were computed by registering a preoperative geometric model with intraoperative 3D fluoroscopic images of the spine. More precisely, a preoperative geometric model was constructed from 28 vertebral landmarks manually identified by an operator on biplanar radiographs acquired preoperatively in standing position. These landmarks were used to obtain a surface model of each vertebra though a dual kriging interpolation technique. The intraoperative model was computed by the registration between this preoperative geometric model and the intraoperative data, composed of a voxelized model obtained from 3D fluoroscopic images. Each vertebra of the voxelized model was segmented and manually identified on intraoperative 3D fluoroscopic images. A rigid registratio

Porcine Spine Finite Element Model of Progressive Experimental Scoliosis and Assessment of a New Dual-Epiphyseal Growth Modulating Implant

RÉSUMÉ La scoliose est une déformation tridimensionnelle de la colonne vertébrale dont l’étiologie reste encore à élucider. Il est généralement admis que la progression de la déformation scoliotique pédiatrique est liée au principe d’Hueter-Volkmann qui stipule une réduction de la croissance suite à des contraintes en compression excessives au niveau de la concavité de la courbure scoliotique vs. sa convexité. Les stratégies de traitement des courbures sont difficiles, surtout chez les jeunes enfants. Typiquement, une intervention chirurgicale avec une instrumentation rachidienne accompagnée d’une arthrodèse segmentaire est nécessaire pour des courbures progressant au-delà de 40° d’angle de Cobb. De nouveaux dispositifs visent à manipuler la croissance vertébrale en exploitant le principe d’Hueter-Volkmann pour contrôler la progression de et corriger la courbure. Ces implants sans fusion exploitent la croissance vertébrale résiduelle en manipulant des gradients de croissance pour localement inverser la cunéiformisation vertébrale et, au fil du temps, réaligner la colonne vertébrale globalement. Des essais cliniques ont démontré une correction prometteuse pour les courbures généralement inférieures à 45°; cependant, les dispositifs actuels chevauchent l’espace du disque intervertébral et le compriment augmentant les risques de dégénérescence du disque à long terme. Par ailleurs, les implants nouvellement conçus sont généralement testés en utilisant des modèles animaux équivalents pour évaluer leur efficacité à corriger des déformations par l'intermédiaire de l’approche inverse (création d'une déformation) ou l’approche à 2- étapes (création d'une déformation suivie d’une correction). Néanmoins, une plate-forme de conception efficace est nécessaire pour évaluer la manipulation de la croissance à court et long termes par de nouveaux implants et de raccourcir le transfert de connaissances vers des applications cliniques. L’objectif général de cette thèse était de développer et de vérifier un modèle par éléments finis porcin (MEFp) unique en tant qu’une plateforme alternative pour la simulation de scolioses expérimentales progressives et des implants sans fusion, et d’évaluer un nouvel implant double-épiphysaire local ne chevauchant pas l’espace du disque sur des porcs immatures. Ainsi, les objectifs spécifiques suivants ont été complétés : 1) développer et----------ABSTRACT Scoliosis is a complex three-dimensional deformity of the spine whose etiology is yet to be elucidated. The pathomechanism of scoliosis progression is believed to be linked to the Hueter-Volkmann principle, by which growth is reduced due to increased growth plate compression, with the inverse also valid. Treatment strategies are challenging, especially in young children. Curves progressing beyond 40° Cobb angle are typically treated via invasive surgical interventions requiring spinal instrumentation accompanied by segmental spinal arthrodesis, impairing spinal mobility. New devices aim at manipulating vertebral growth by exploiting the Hueter-Volkmann principle to control curvature progression. These fusionless implants harness remaining vertebral growth by manipulating growth gradients to reverse vertebral wedging locally and, over time, globally realign the spine. Clinical trials have demonstrated promising deformity correction for curves generally below 45°; however, current devices bridge the intervertebral disc gap and predominantly compress the disc increasing the risks of longterm disc degeneration. Moreover, in a time-consuming manner, newly designed implants are commonly tested using equivalent animal models to assess their efficacy in correcting spinal deformities via the inverse (creation of a deformity) or the 2-step approaches (creation of a deformity followed by its subsequent correction). Nevertheless, a solid design platform is required to evaluate the short- and long-term growth manipulating efficacy of new implant designs and shorten knowledge transfer to clinical applications. The general objective of this thesis was to develop and verify a unique porcine spine finite element model (pFEM) as an alternative testing platform for the simulation of progressive experimental scoliosis and fusionless implants, and assess a new localized dualepiphyseal implant on immature pigs. Thus, specific objectives were devised as follows: 1) develop and verify a distinctive pFEM of the spine and ribcage, 2) develop and test, in vivo, a dual-epiphyseal implant incorporating a custom expansion mechanism, 3) exploit the developed pFEM to investigate differences between the inverse and 2-step fusionless implant testing approaches, and 4) exploit the pFEM to evaluate the biomechanical contribution of the ribcage in fusionless scoliosis surgery

Three Dimensional Nonlinear Statistical Modeling Framework for Morphological Analysis

This dissertation describes a novel three-dimensional (3D) morphometric analysis framework for building statistical shape models and identifying shape differences between populations. This research generalizes the use of anatomical atlases on more complex anatomy as in case of irregular, flat bones, and bones with deformity and irregular bone growth. The foundations for this framework are: 1) Anatomical atlases which allow the creation of homologues anatomical models across populations; 2) Statistical representation for output models in a compact form to capture both local and global shape variation across populations; 3) Shape Analysis using automated 3D landmarking and surface matching. The proposed framework has various applications in clinical, forensic and physical anthropology fields. Extensive research has been published in peer-reviewed image processing, forensic anthropology, physical anthropology, biomedical engineering, and clinical orthopedics conferences and journals. The forthcoming discussion of existing methods for morphometric analysis, including manual and semi-automatic methods, addresses the need for automation of morphometric analysis and statistical atlases. Explanations of these existing methods for the construction of statistical shape models, including benefits and limitations of each method, provide evidence of the necessity for such a novel algorithm. A novel approach was taken to achieve accurate point correspondence in case of irregular and deformed anatomy. This was achieved using a scale space approach to detect prominent scale invariant features. These features were then matched and registered using a novel multi-scale method, utilizing both coordinate data as well as shape descriptors, followed by an overall surface deformation using a new constrained free-form deformation. Applications of output statistical atlases are discussed, including forensic applications for the skull sexing, as well as physical anthropology applications, such as asymmetry in clavicles. Clinical applications in pelvis reconstruction and studying of lumbar kinematics and studying thickness of bone and soft tissue are also discussed

Machine learning in orthopedics: a literature review

In this paper we present the findings of a systematic literature review covering the articles published in the last two decades in which the authors described the application of a machine learning technique and method to an orthopedic problem or purpose. By searching both in the Scopus and Medline databases, we retrieved, screened and analyzed the content of 70 journal articles, and coded these resources following an iterative method within a Grounded Theory approach. We report the survey findings by outlining the articles\u2019 content in terms of the main machine learning techniques mentioned therein, the orthopedic application domains, the source data and the quality of their predictive performance

Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf