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A three-dimensional (3D) reconstruction algorithm based on contours identification from biplanar radiographs is presented. It requires, as technical prerequisites, a method to calibrate the biplanar radiographic environment and a surface generic object (anatomic atlas model) representing the structure to be reconstructed. The reconstruction steps consist of: the definition of anatomical regions, the identification of 2D contours associated to these regions, the calculation of 3D contours and projection onto the radiographs, the associations between points of the X-rays contours and points of the projected 3D contours, the optimization of the initial solution and the optimized object deformation to minimize the distance between X-rays contours and projected 3D contours. The evaluation was performed on 8 distal femurs comparing the 3D models obtained to CT-scan reconstructions. Mean error for each distal femur was 1 mm.

3D personalized models are more and more requested for clinical and biomechanical studies. Techniques based on bi-planar X-rays present the advantage of a low radiation dose for the patient. However, up to now, such techniques have shown limited accuracy in the case of pelvis reconstruction. This study proposes and validates a method providing accurate 3D personalized model of the pelvis from bi-planar X-rays. The algorithm is based on the fast computation of an initial solution followed by local deformations based on 2D anatomical points and contours that are digitized in both radiographs. Results were close to CT-scan reconstructions (mean difference 1.6 mm and differences under 4.3 mm for 95% of the points). Moreover, 3D morphometry of the pelvis could be obtained with an accuracy of 5%. This technique provides 3D patient specific model with a low radiation dose.

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. There is a lack of numeric data for the mechanical characterization of spine muscles, especially in vivo data. The multifidus muscle is a major muscle for the stabilization of the spine and may be involved in the pathogenesis of chronic low back pain (LBP). Supersonic shear wave elastography (SWE) has not yet been used on back muscles. The purpose of this prospective study is to assess the feasibility of ultrasound SWE to measure the elastic modulus of lumbar multifidus muscle in a passive stretching posture and at rest with a repeatable and reproducible method.

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. CT-scans of 48 children, aged four months to 15 years. The geometry of the sternum was detailed 40 and nine parameters were used to describe the ribs and rib cages. A "costal index" was defined as 41 the ratio between cartilage length and whole rib length to evaluate the cartilage ratio for each rib 42 level. For all children, the costal index decreased from rib level one to three and increased from 43 level three to seven. For all levels, the cartilage accounted for 45 to 60% of the rib length, and was 44 longer for the first years of life. The mean costal index decreased by 21% for subjects over three 45 years old compared to those under three (p<10 -4 ). The volume of the sternebrae was found to be 46 highly age dependent. Such data could be useful to define the standard geometry of the paediatric 47 thorax and help to detect clinical abnormalities. 48

The stereoradiographic reconstruction method allows obtaining the three-dimensional (3D) rib cage geometry, which is essential for clinical evaluation or biomechanical studies. However, reconstruction time is still high (about 20 min considering operator time). The purpose of this study is to propose a 3D reconstruction of the rib cage from biplanar radiographs, based on the deformation of a prepersonalized object. Validation in comparison with computed tomography (CT-scan) acquisitions was performed. Local parameters (rib length, cord length, maximum width, area, and rib orientations) were computed from reconstructions. Parameters' reproducibility was assessed with two observers and two measurements for 15 subjects. Regarding validation of the parameters, the mean difference with the CT-scan was between 6.3 and 1.3%. Observer variability was maximal for rib area (6.2%) and was lower than 4.2% for others parameters. The proposed reconstruction method reduced time (less than three minutes for operator time) to obtain a 3D reconstruction of the rib cage.