Constrained Statistical Modelling of Knee Flexion from Multi-Pose Magnetic Resonance Imaging

© 1982-2012 IEEE.Reconstruction of the anterior cruciate ligament (ACL) through arthroscopy is one of the most common procedures in orthopaedics. It requires accurate alignment and drilling of the tibial and femoral tunnels through which the ligament graft is attached. Although commercial computer-Assisted navigation systems exist to guide the placement of these tunnels, most of them are limited to a fixed pose without due consideration of dynamic factors involved in different knee flexion angles. This paper presents a new model for intraoperative guidance of arthroscopic ACL reconstruction with reduced error particularly in the ligament attachment area. The method uses 3D preoperative data at different flexion angles to build a subject-specific statistical model of knee pose. To circumvent the problem of limited training samples and ensure physically meaningful pose instantiation, homogeneous transformations between different poses and local-deformation finite element modelling are used to enlarge the training set. Subsequently, an anatomical geodesic flexion analysis is performed to extract the subject-specific flexion characteristics. The advantages of the method were also tested by detailed comparison to standard Principal Component Analysis (PCA), nonlinear PCA without training set enlargement, and other state-of-The-Art articulated joint modelling methods. The method yielded sub-millimetre accuracy, demonstrating its potential clinical value

[Diffusion-weighted MR imaging of liver pathology: principles and clinical applications].

International audienceDue to ongoing technological advances, the range of clinical applications for diffusion-weighted MR imaging has expanded to now include abdominal pathology. Current applications for liver pathology include two main directions. First, oncologic imaging with detection, characterization and follow-up of lesions. Second, evaluation of diffuse liver diseases, including hepatic fibrosis. The diagnostic impact and role of diffusion-weighted MR imaging remain under investigation, but appear promising. Because of its short acquisition time, sensitivity, and additional information it provides, diffusion-weighted MR imaging should be included in routine liver imaging protocols

Front-back gate coupling effect on 1/f noise in ultra-thin Si film FDSOI MOSFETs

International audienceLow-frequency (LF) noise was studied on 28 nm CMOS technology FDSOI devices with ultra-thin silicon film (7 nm) and thin buried oxide (25 nm). The noise level was observed to be strongly dependent on the combination of the front and back gate biasing voltages. This was explained by the coupling effect of both Si/High-K dielectric and Si/SiO 2 interface noise sources (channel/front oxide and channel/buried oxide), in combination with the variation of the Remote Coulomb scattering coefficient α. From comparison of the experimental and simulation results, it is illustrated that the main reason of this dependence is the distance between the charge distribution centroid and the interfaces, which is also controlled by both front and back-gate bias voltages, and the way this distance affects the Remote Coulomb scattering coefficient α. A new LF noise model approach is suggested to include the impact of all these parameters, and also allows us to extract the oxide trap density values for both interfaces