Adultes avec déformation rachidienne : traitement chirurgical et évaluation musculaire

Adult spinal deformity(ASD) refers to abnormal curvatures of the spine in patients who have completed their growth. Due to its prevalence, clinical impact, and the relatively high rate of surgical failures, they represent a therapeutic challenge. Research has been able to demonstrate that the preservation or the restoration of the sagittal alignment, are key objectives of surgical treatment. The objective of this thesis is to analyze the treatment of ASD patients, with particular interest in restoration of sagittal alignment and to develop tools to assess the spino-pelvic musculature of ASD patients. Based on an analysis of a multicenter database, the first two articles present an evaluation of the surgical treatment in term of clinical effectiveness and radiographic realignment. In addition, the discrepancies between surgical preoperative planning and operative execution have been studied with a prospective data collection, and have highlighted the necessity to understand better the role of the muscles in the maintaining of the posture. Therefore two methods for the characterization of the muscles involved in the sagittal alignment have been validated. Both methods are based on manual segmentation of specific MRI acquisition (Dixon methods) in order to obtain precise fat infiltration quantification in addition to muscular volume. One method permits to obtain 3D reconstruction able to generate patient–specific musculoskeletal model. The other one open the path to a clinical purpose, because necessitate only segmentation of four slices to obtain an relevant evaluation of the muscular system. Finally, thanks to the first protocol the muscular system of ASD patients have been described.Les déformations rachidiennes se réfèrent aux patients avec une courbure anormal de la colonne vertébrale qui ont terminé leur croissance. Par leur prévalence, leur impact clinique, et le taux relativement élevé d'échecs chirurgicaux, elles représentent un défi thérapeutique. La recherche a permis de démontrer que la préservation ou la restauration de l'alignement, sont des éléments clé du traitement chirurgical. L'objectif de cette thèse était d'analyser le traitement des patients avec DR, avec un intérêt particulier pour la restauration de l'alignement sagittal et l'évaluation musculaire. Fondé sur une analyse rétrospective d'une base de données multicentriques, les deux premiers articles présentent une évaluation du traitement chirurgical en termes d'efficacité clinique et de réalignement radiographique. Les écarts entre la planification préopératoire et l'exécution opérationnelle ont aussi été étudiés avec une collecte de données prospectives, et ont mis en évidence la nécessité de mieux comprendre le rôle des muscles dans le maintien de la posture. Par conséquent, deux protocoles pour la caractérisation des principaux muscles impliqués dans l'alignement sagittal ont été validés. Les deux méthodes sont basées sur la segmentation manuelle d'acquisition IRM spécifique (méthode de Dixon) afin d'obtenir l'infiltration graisseuse en plus du volume musculaire. Une des méthodes permet d'obtenir la reconstruction 3D des muscles et donc de générer des modèles musculo-squelettiques personnalisés. L'autre ouvre la voie à une pratique clinique car nécessite seulement la segmentation de quatre coupes pour obtenir une évaluation des principaux groupes musculaires. Enfin, à partir de la première méthode, le système musculaire de patients avec DR a été décrit

Biomimetic phantom with anatomical accuracy for evaluating brain volumetric measurements with magnetic resonance imaging

Purpose: Brain image volumetric measurements (BVM) methods have been used to quantify brain tissue volumes using magnetic resonance imaging (MRI) when investigating abnormalities. Although BVM methods are widely used, they need to be evaluated to quantify their reliability. Currently, the gold-standard reference to evaluate a BVM is usually manual labeling measurement. Manual volume labeling is a time-consuming and expensive task, but the confidence level ascribed to this method is not absolute. We describe and evaluate a biomimetic brain phantom as an alternative for the manual validation of BVM. Methods: We printed a three-dimensional (3D) brain mold using an MRI of a three-year-old boy diagnosed with Sturge-Weber syndrome. Then we prepared three different mixtures of styrene-ethylene/butylene-styrene gel and paraffin to mimic white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF). The mold was filled by these three mixtures with known volumes. We scanned the brain phantom using two MRI scanners, 1.5 and 3.0 Tesla. Our suggestion is a new challenging model to evaluate the BVM which includes the measured volumes of the phantom compartments and its MRI. We investigated the performance of an automatic BVM, i.e., the expectation–maximization (EM) method, to estimate its accuracy in BVM. Results: The automatic BVM results using the EM method showed a relative error (regarding the phantom volume) of 0.08, 0.03, and 0.13 (±0.03 uncertainty) percentages of the GM, CSF, and WM volume, respectively, which was in good agreement with the results reported using manual segmentation. Conclusions: The phantom can be a potential quantifier for a wide range of segmentation methods

The state-of-the-art in ultrasound-guided spine interventions.

During the last two decades, intra-operative ultrasound (iUS) imaging has been employed for various surgical procedures of the spine, including spinal fusion and needle injections. Accurate and efficient registration of pre-operative computed tomography or magnetic resonance images with iUS images are key elements in the success of iUS-based spine navigation. While widely investigated in research, iUS-based spine navigation has not yet been established in the clinic. This is due to several factors including the lack of a standard methodology for the assessment of accuracy, robustness, reliability, and usability of the registration method. To address these issues, we present a systematic review of the state-of-the-art techniques for iUS-guided registration in spinal image-guided surgery (IGS). The review follows a new taxonomy based on the four steps involved in the surgical workflow that include pre-processing, registration initialization, estimation of the required patient to image transformation, and a visualization process. We provide a detailed analysis of the measurements in terms of accuracy, robustness, reliability, and usability that need to be met during the evaluation of a spinal IGS framework. Although this review is focused on spinal navigation, we expect similar evaluation criteria to be relevant for other IGS applications

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

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): Guidelines for medical 3D printing and appropriateness for clinical scenarios

Este número da revista Cadernos de Estudos Sociais estava em organização quando fomos colhidos pela morte do sociólogo Ernesto Laclau. Seu falecimento em 13 de abril de 2014 surpreendeu a todos, e particularmente ao editor Joanildo Burity, que foi seu orientando de doutorado na University of Essex, Inglaterra, e que recentemente o trouxe à Fundação Joaquim Nabuco para uma palestra, permitindo que muitos pudessem dialogar com um dos grandes intelectuais latinoamericanos contemporâneos. Assim, buscamos fazer uma homenagem ao sociólogo argentino publicando uma entrevista inédita concedida durante a sua passagem pelo Recife, em 2013, encerrando essa revista com uma sessão especial sobre a sua trajetória

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Abstract Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.https://deepblue.lib.umich.edu/bitstream/2027.42/146524/1/41205_2018_Article_30.pd

Establishing an evidence-base for erect pelvis radiography : positioning, radiation dose and image quality

Purpose: Pelvic radiography using X-ray imaging has traditionally been used for the identification of hip joint changes, including the identification of pathologies such as osteoarthritis. For patients suffering from hip pain, the supine pelvis X-ray examination is one of the initial diagnostic steps. Despite this, many recent studies have recommended that the position should now be undertaken erect and not supine to reflect the functional appearances of the hip joint. This thesis aims to establish an evidence base for erect pelvis radiography, and it will include assessing radiographic positioning, radiation dose and image quality. Methods: The experimental work described in this thesis was conducted in three phases. Each phase has its own methods with the purpose of achieving a specific set of aims. Phase One was the evaluation of the postural effects of different erect (standing) positions in order to recommend an optimal one for erect pelvic radiography. Eight different erect positions were investigated. A sample group of 67 healthy people participated, and a range of spinal and pelvis measurements were acquired using a 3D video rasterography system (Diers) and an inclinometer.Phase Two was a phantom study evaluating the potential changes to radiation dose and image quality when moving between supine and erect imaging. Phase two was undertaken using three experiments (experiment #1, experiment #2 and experiment #3). Experiment #1 evaluated the impact of increased patient size on the radiation dose and image quality. In this experiment, animal fat was positioned anteriorly on a pelvic anthropomorphic phantom and the thickness increased incrementally in 1cm steps from 1 to 15cm. Image quality was evaluated physically and visually. The effective dose was calculated using Monte Carlo simulation software (PCXMC). During experiment #2, the anterior thicknesses for 109 patients, with a range of BMIs, who were referred for pelvis radiography, was measured in the erect and supine position. Experiment #3 evaluated the potential differences between the positions (supine and erect) in terms of image quality and radiation dose by modelling patient thickness changes between positions using the data obtained in experiment #2. An anthropomorphic phantom was used and modified (by adding additional fat) to simulate tissue changes for both erect and supine X-ray positions. Visual grading analysis was used (VGA) to evaluate image quality. The effective dose and absorbed dose were calculated using PCXMC.During Phase Three, 60 patients were imaged in erect and supine positions. The paired pelvis X-ray images were then compared, taking into account radiation dose and image quality.Results: Phase One demonstrated no statistical differences between the eight-different standing positions for pelvic and spine metrics (P>0.05). Results also demonstrated no significant postural differences between BMIs across all eight standing positions (P>0.05). Also, no differences (P>0.05) were identified in the pelvis and spinal metrics when comparing between males and females .Standing relaxed with feet internally rotated by 20°and the upper arms supported was a recommendation derived from this phase. Results from Phase Two showed an increase in effective dose (E) as the fat thickness increased. Also, all physical and visual image quality metrics decreased as fat thickness increased. Physical and visual image quality measures also decreased for erect images when compared to supine images, and the E also increased. 90kVp, 130/145 SID, using both outer chambers, were the recommended exposure parameters settings for obtaining erect pelvis X-ray images. Results from Phase Three showed that anterior patient thickness was 17% (P<0.001) higher in an erect position .The DAP and absorbed dose were 46% and 45% (P<0.001) greater in the erect position. Also, the effective dose was 67% (P<0.001) higher in the erect position when compared with supine. In regard to the image quality (IQ), that of the erect position decreased by 10% when compared with supine (P<0.001).Conclusion: The eight proposed standing positions could theoretically be suitable for erect pelvis imaging. People in a relaxed standing position, with their feet internally rotated by 20°and their upper arms supported would be recommended. In terms of IQ and radiation dose for erect positions, this position decreases image quality (both physical and visual) and increased radiation dose. Changes were largely due to the effect of gravity on the anterior soft tissue distribution. These issues should be considered and optimised more fully when deciding if to move from supine to erect pelvis imaging