Accepted Manuscript. Ultrasound in Medicine and Biologyy. The original publication is available at www.sciencedirect.com. DOI: doi:10.1016/j.ultrasmedbio.2015.04.020.Development of shear wave elastography gave access to non-invasive muscle stiffness assessment in vivo. The aim of the present study was to define a measurement protocol to quantify the shear modulus of lower limb muscles in order to be used in clinical routine. Four positions were defined to evaluate shear modulus, parallel to the fibers, in the anterior and posterior aspect of the lower limb, at rest and during passive stretching, of 10 healthy subjects. Reliability was first evaluated on 2 muscles by 3 operators, measurements were repeated 6 times. Then, reliability comparison of different muscle was evaluated on 11 muscles by 2 operators, measurements repeated 3 times. Reproducibility of shear modulus was 0.48 kPa and repeatability was 0.41 kPa, with all muscles pooled. The position did not significantly influence the reliability. SWE appeared as an appropriate and reliable tool to evaluate shear modulus of lower limb muscles with the proposed protocol.

A new approach called the``variational theory of complex rays'' (VTCR) is developed for calculating the vibrations of weakly damped elastic structures in the medium-frequency range. Here, the emphasis is put on the most fundamental aspects. The effective quantities (elastic energy, vibration intensity, etc.) are evaluated after solving a small system of equations which does not derive from a finite element discretization of the structure. Numerical examples related to plates show the appeal and the possibilities of the VTCR.

IntroductionTo evaluate the accuracy of CAD/CAM generated splints in orthognathic surgery by comparing planned versus actual post-operative 3D images.MethodsSpecific planning software (SimPlant® OMS Standalone 14.0) was used to perform a 3D virtual Le Fort I osteotomy in 10 fresh human cadaver heads. Stereolithographic splints were then generated and used during the surgical procedure to reposition the maxilla according to the planned position. Pre-operative planned and postoperative 3D CT scan images were fused and imported to dedicated software (MATLAB®) 7.11.) for calculating the translational and rotational (pitch, roll and yaw) differences between the two 3D images. Geometrical accuracy was estimated using the Root Mean Square Deviations (RMSD) and lower and upper limits of accuracy were computed using the Bland & Altman method, with 95 % confidence intervals around the limits. The accuracy cutoff was set at +/− 2 mm for translational and ≤ 4° for rotational measurements.ResultsOverall accuracy between the two 3D images was within the accuracy cutoff for all values except for the antero-posterior positioning of the maxilla (2.17 mm). The translational and rotational differences due to the splint were all within the accuracy cutoff. However, the width of the limits of agreement (range between lower and upper limits) showed that rotational differences could be particularly large.ConclusionThis study demonstrated that maxillary repositioning can be accurately approximated and thus predicted by specific computational planning and CAD/CAM generated splints in orthognathic surgery. Further study should focus on the risk factors for inaccurate prediction.