The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Manuel Paiva - One of the best experts on this subject based on the ideXlab platform.
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microgravity alters respiratory abdominal and Rib Cage motion during sleep
Journal of Applied Physiology, 2009Co-Authors: Kim G Prisk, Manuel PaivaAbstract:The abdominal and Rib Cage contRibutions to tidal breathing differ between rapid-eye-movement (REM) and non-NREM sleep. We hypothesized that abdominal relative contRibution during NREM and REM slee...
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Rib Cage shape and motion in microgravity.
Journal of Applied Physiology, 1992Co-Authors: M. Estenne, Vincent Ninane, M. Gorini, A. Van Muylem, Manuel PaivaAbstract:We studied the effect of microgravity (0 Gz) on the anteroposterior diameters of the upper (URC-AP) and lower (LRC-AP) Rib Cage, the transverse diameter of the lower Rib Cage (LRC-TR), and the xiphipubic distance and on the electromyographic (EMG) activity of the scalene and parasternal intercostal muscles in five normal subjects breathing quietly in the seated posture. Gastric pressure was also recorded in four subjects. At 0 Gz, end-expiratory LRC-AP and xiphipubic distance increased but LRC-TR invariably decreased, as did end-expiratory gastric pressure. No consistent effect was observed on tidal LRC-TR and xiphipubic displacements, but tidal changes in URC-AP and LRC-AP were reduced. Although scalene and parasternal phasic inspiratory EMG activity tended to decrease at 0 Gz, both muscle groups demonstrated an increase in tonic activity. We conclude that during brief periods of weightlessness 1) the Rib Cage at end expiration is displaced in the cranial direction and adopts a more circular shape, 2) the tidal expansion of the ventral Rib Cage is reduced, particularly in its upper portion, and 3) the scalenes and parasternal intercostals generally show a decrease in phasic inspiratory EMG activity and an increase in tonic activity.
Kim G Prisk - One of the best experts on this subject based on the ideXlab platform.
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microgravity alters respiratory abdominal and Rib Cage motion during sleep
Journal of Applied Physiology, 2009Co-Authors: Kim G Prisk, Manuel PaivaAbstract:The abdominal and Rib Cage contRibutions to tidal breathing differ between rapid-eye-movement (REM) and non-NREM sleep. We hypothesized that abdominal relative contRibution during NREM and REM slee...
Tobias Klinder - One of the best experts on this subject based on the ideXlab platform.
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3D reconstruction of the human Rib Cage from 2D projection images using a statistical shape model
International Journal of Computer Assisted Radiology and Surgery, 2010Co-Authors: Jalda Dworzak, Hans Lamecker, Heiko Seim, Jens Berg, Dagmar Kainmüller, Cristian Lorenz, Hans-christian Hege, Tobias Klinder, Stefan ZachowAbstract:Purpose This paper descRibes an approach for the three-dimensional (3D) shape and pose reconstruction of the human Rib Cage from few segmented two-dimensional (2D) projection images. Our work is aimed at supporting temporal subtraction techniques of subsequently acquired radiographs by establishing a method for the assessment of pose differences in sequences of chest radiographs of the same patient. Methods The reconstruction method is based on a 3D statistical shape model (SSM) of the Rib Cage, which is adapted to binary 2D projection images of an individual Rib Cage. To drive the adaptation we minimize a distance measure that quantifies the dissimilarities between 2D projections of the 3D SSM and the projection images of the individual Rib Cage. We propose different silhouette-based distance measures and evaluate their suitability for the adaptation of the SSM to the projection images. Results An evaluation was performed on 29 sets of biplanar binary images (posterior–anterior and lateral). Depending on the chosen distance measure, our experiments on the combined reconstruction of shape and pose of the Rib Cages yield reconstruction errors from 2.2 to 4.7mm average mean 3D surface distance. Given a geometry of an individual Rib Cage, the rotational errors for the pose reconstruction range from 0.1° to 0.9°. Conclusions The results show that our method is suitable for the estimation of pose differences of the human Rib Cage in binary projection images. Thus, it is able to provide crucial 3D information for registration during the generation of 2D subtraction images.
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Towards model-based 3-D reconstruction of the human Rib Cage from radiographs
2008Co-Authors: Jalda Dworzak, Hans Lamecker, Heiko Seim, Cristian Lorenz, Hans-christian Hege, Tobias Klinder, Jens Von Berg, Dagmar Kainmueller, Stefan ZachowAbstract:This work is concerned with the three-dimensional (3-d) shape and pose reconstruction of the human Rib Cage from few two-dimensional (2-d) radiographs. The reconstruction method is based on a statistical shape model of the Rib Cage that is adapted to the 2-d image data of a patient. An underlying optimization process minimizes a distance measure which quantifies the dissimilarities between 2-d projections of the 3-d shape model and the X-ray images and thereby estimates the shape model’s parameters. We propose a distance measure especially suited for the topology of the Rib Cage. A validation was performed on 29 sets of simulated, biplanar X-ray images.
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automated model based Rib Cage segmentation and labeling in ct images
Medical Image Computing and Computer-Assisted Intervention, 2007Co-Authors: Tobias Klinder, Cristian Lorenz, Jens Von Berg, Sebastian Peter Michael Dries, Thomas Bulow, Jorn OstermannAbstract:We present a new model-based approach for an automated labeling and segmentation of the Rib Cage in chest CT scans. A mean Rib Cage model including a complete vertebral column is created out of 29 data sets. We developed a ray search based procedure for Rib Cage detection and initial model pose. After positioning the model, it was adapted to 18 unseen CT data. In 16 out of 18 data sets, detection, labeling, and segmentation succeeded with a mean segmentation error of less than 1.3 mm between true and detected object surface. In one case the Rib Cage detection failed, in another case the automated labeling.
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MICCAI (2) - Automated model-based Rib Cage segmentation and labeling in CT images
Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Inte, 2007Co-Authors: Tobias Klinder, Cristian Lorenz, Jens Von Berg, Sebastian Peter Michael Dries, Thomas Bulow, Jorn OstermannAbstract:We present a new model-based approach for an automated labeling and segmentation of the Rib Cage in chest CT scans. A mean Rib Cage model including a complete vertebral column is created out of 29 data sets. We developed a ray search based procedure for Rib Cage detection and initial model pose. After positioning the model, it was adapted to 18 unseen CT data. In 16 out of 18 data sets, detection, labeling, and segmentation succeeded with a mean segmentation error of less than 1.3 mm between true and detected object surface. In one case the Rib Cage detection failed, in another case the automated labeling.
Albert B. Schultz - One of the best experts on this subject based on the ideXlab platform.
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Rib Cage deformities in scoliosis : spine morphology, Rib Cage stiffness, and tomography imaging
Journal of Orthopaedic Research, 1993Co-Authors: Robert F. Closkey, Albert B. SchultzAbstract:A computer-implemented biomechanical model of a thoracolumbar spine and deformable Rib Cage was used to investigate the influence of spine morphology and Rib Cage stiffness properties on the Rib Cage deformities that arise from scoliosis and to study the relationship of actual Rib distortions with those seen on computed tomography (CT) scans. For the purposes of this study, it was assumed that Rib Cage deformities result from forces imposed on the Ribs by the deforming spine. When a structurally normal Rib Cage was allowed to follow freely the imposition of scoliotic curves on the spine, different configurations of scoliosis led to substantial differences in the resulting Rib Cage deformities. Rib Cage lateral offset correlated well with the Cobb angle of the scoliosis but not with the apical vertebral axial rotation, whereas Rib Cage axial rotation correlated well with apical vertebral axial rotation but not with the Cobb angle. These model-obtained findings mirror clinical findings that correction of the Cobb angle leads to correction of the lateral offset of the Rib Cage but does not correlate well with correction of the Rib Cage axial rotation. The stiffnesses of the ligamentous tissue connecting the sternum to the pelvis, of the costovertebral joints, and of the Ribs themselves also influenced the Rib deformities substantially. The influence of the sternopelvic ligamentous ties has not been recognized previously. The total Rib Cage volume remained essentially constant regardless of the severity of the resulting deformity, but the distRibution of this volume between convex and concave sides varied somewhat.(ABSTRACT TRUNCATED AT 250 WORDS)
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A model for studies of the deformable Rib Cage.
Journal of Biomechanics, 1992Co-Authors: Robert F. Closkey, Albert B. Schultz, Carl W. LuchiesAbstract:An earlier model for the study of Rib Cage mechanics was modified so that Rib deformity in scoliosis could be better represented. The rigid Ribs of that model were replaced by five-segment deformable Ribs. Literature data on cadaver Rib mechanical behavior were used to assign stiffnesses to the new individual model Ribs so that experimental and model hb deflections agreed. Shear and tension/compression stiffnesses had little effect on individual Rib deformation, but bending stiffnesses had a major effect. Level-to-level differences in mechanical behavior could be explained almost exclusively by level to level differences in the Rib shape. The model Ribs were then assembled into a whole Rib Cage. Computer simulations of whole Rib Cage behaviors, both in uiuo and in vitro, showed a reasonable agreement with the measured behaviors. The model was used to study Rib Cage mechanics in two scolioses, one with a 43" and the other with a 70 Cobb angle. Scoliotic Rib Cage deformities were quantified by parameters measuring the Rib Cage lateral offset, Rib Cage axial rotation, Rib Cage volume and Rib distortion. Rib distortion was quantified both in best- fit and simulated computer tomography (CT) scan planes. Model Rib distortion was much smaller in best-fit planes than in CT planes. The total Rib Cage volume changed little in the presence of the scolioses, but it became asymmetrically distRibuted.
Georg Bergmann - One of the best experts on this subject based on the ideXlab platform.
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Effects of the Rib Cage on Thoracic Spine Flexibility / Einfluss des Brustkorbs auf die Flexibilität der Brustwirbelsäule
Biomedizinische Technik, 2005Co-Authors: M. L Sham, Thomas Zander, Antonius Rohlmann, Georg BergmannAbstract:: Besides protecting the internal organs of the thorax, the Rib Cage is the site of numerous muscle attachments. It also decreases the overall flexibility of the thoracic spine. This study developed finite element (FE) models of the thoracic spine with and without the Rib Cage, and the effects of the Rib Cage on thoracic spine flexibility were determined. The numerical models were validated by comparing the maximum rotation of the models for several loading cases with experimental data in the literature. After adapting the material properties for the discs and ligaments, the calculated maximum rotations differed from the measured median values by less than 1 degrees without the Rib Cage and by less than 2.5 degrees with it. The Rib Cage decreased the mean flexibility of the thoracic spine by 23% to 47%, depending on the loading plane. Assuming the Ribs to be rigid beams required a corresponding reduction of ligament stiffnesses in order to achieve the same agreement of the maximum rotations with the measured median values. Interconnecting the FE thoracic spine model plus Rib Cage with the existing detailed FE lumbar spine model improves the simulation of force directions of muscles attached to the Rib Cage or thoracolumbar spine. In addition, such a model is suitable for determining the effects of lumbar spine implants on spinal balance.
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effects of the Rib Cage on thoracic spine flexibility einfluss des brustkorbs auf die flexibilitat der brustwirbelsaule
Biomedizinische Technik, 2005Co-Authors: M. L Sham, Thomas Zander, Antonius Rohlmann, Georg BergmannAbstract:Besides protecting the internal organs of the thorax, the Rib Cage is the site of numerous muscle attachments. It also decreases the overall flexibility of the thoracic spine. This study developed finite element (FE) models of the thoracic spine with and without the Rib Cage, and the effects of the Rib Cage on thoracic spine flexibility were determined. The numerical models were validated by comparing the maximum rotation of the models for several loading cases with experimental data in the literature. After adapting the material properties for the discs and ligaments, the calculated maximum rotations differed from the measured median values by less than 1 degrees without the Rib Cage and by less than 2.5 degrees with it. The Rib Cage decreased the mean flexibility of the thoracic spine by 23% to 47%, depending on the loading plane. Assuming the Ribs to be rigid beams required a corresponding reduction of ligament stiffnesses in order to achieve the same agreement of the maximum rotations with the measured median values. Interconnecting the FE thoracic spine model plus Rib Cage with the existing detailed FE lumbar spine model improves the simulation of force directions of muscles attached to the Rib Cage or thoracolumbar spine. In addition, such a model is suitable for determining the effects of lumbar spine implants on spinal balance.
