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Contexte Les troubles fonctionnels de la main sont généralement investigués, en premier lieu, à l’aide de l’imagerie radiographique conventionnelle. Cependant, les radiographies (deux dimensions (2D)) fournissent des renseignements limités, et l’information peut être réduite par le chevauchement des os et les biais de projection. Ce travail présente une méthode de reconstruction de la main en trois dimensions (3D) à partir de radiographies biplanes. Méthode Cette approche consiste en la déformation d’un modèle générique de main sur les radiographies biplanes par des processus manuels et automatiques. L’examen de référence étant la segmentation manuelle scanographique, la précision de la méthode a été évaluée par une comparaison entre les reconstructions à partir de radiographies biplanes et les reconstructions correspondantes à partir de scanner (0,3 mm d’épaisseur de coupe). Pour évaluer la reproductibilité de la méthode, 6 mains saines (6 sujets, 3 gauches, 3 hommes) ont été considérées. Deux opérateurs ont répété trois fois chaque reconstruction à partir de radiographies biplanes pour étudier la variabilité inter- et intra-opérateur. Trois paramètres anatomiques, qui pourraient être calculés automatiquement à partir des reconstructions, ont été considérés à partir des surfaces osseuses : la longueur du scaphoïde, la profondeur de l’extrémité distale du radius et la hauteur du trapèze. Résultats Le double de l’erreur quadratique moyenne (2 Root Mean Square, 2RMS), au niveau de la différence point/surface entre les radiographies biplanes et les reconstructions tomodensitométriques, variait de 0,46 mm pour les phalanges distales à 1,55 mm pour les os de la deuxième rangée. La variabilité inter-/intra-observateur a montré une précision à 95 % de l’intervalle de confiance inférieure à 1,32 mm, pour les paramètres anatomiques, et à 2,12 mm pour les barycentres osseux. Discussion La méthode actuelle permet d’obtenir une reconstruction 3D précise de la main et du poignet par rapport au scanner segmenté traditionnel. En améliorant l’automatisation de la méthode, cela nous permettrait d’obtenir rapidement des informations objectives sur la position des os dans l’espace. L’intérêt de cette méthode réside dans le diagnostic précoce de certaines pathologies ligamentaires (instabilité carpienne) et a également des implications dans la planification chirurgicale et la modélisation personnalisée par éléments finis.

Three-dimensional bone reconstructions from medical imaging are essential for biomechanical modelling and are growing tools in clinics. Several methods of lower limbs reconstruction from biplanar radiographs have been proposed in the literature but with significant operator dependence. A novel reconstruction method based on reduced manual annotation, statistical shape models and fully automatic adjustments was proposed in this study. While significantly reducing operator intervention, the proposed method demonstrated similar or better precision than previous approaches on clinical parameters. Meanwhile, shape accuracy was improved to around 1mm. By quasi-automating the 3D reconstruction without loss of accuracy and precision, the proposed approach is a considerable step towards extensive use of 3D personalized models in clinical routine and large cohort biomechanical studies. Chaire BiomecAM

This study aims to investigate the effects of workplace noise on neural activity and alpha asymmetries of the prefrontal cortex (PFC) during mental stress conditions. Workplace noise exposure is a pervasive environmental pollutant and is negatively linked to cognitive effects and selective attention. Generally, the stress theory is assumed to underlie the impact of noise on health. Evidence for the impacts of workplace noise on mental stress is lacking. Fifteen healthy volunteer subjects performed the Montreal imaging stress task in quiet and noisy workplaces while their brain activity was recorded using electroencephalography. The salivary alpha-amylase (sAA) was measured before and immediately after each tested workplace to evaluate the stress level. The results showed a decrease in alpha rhythms, or an increase in cortical activity, of the PFC for all participants at the noisy workplace. Further analysis of alpha asymmetry revealed a greater significant relative right frontal activation of the noisy workplace group at electrode pairs F4-F3 but not F8-F7. Furthermore, a significant increase in sAA activity was observed in all participants at the noisy workplace, demonstrating the presence of stress. The findings provide critical information on the effects of workplace noise-related stress that might be neglected during mental stress evaluations. Ministry of Higher Education Malaysia under the Higher Institutional Centre of Excellence (HICoE) Scheme

International audience; X-ray based quantitative analysis of spine parameters is required in routine diagnosis or treatment planning. Existing tools commonly require manual intervention. Attempts towards automation of the whole procedure have mainly focused on vertebral bodies, whereas other regions such as the posterior arch also bear considerable amount of useful information. In this study, we combine a specific design of contextual visual features with a multi-class Random Forest classifier to perform pixel-wise segmentation and identification of all cervical spine spinous processes, on sagittal radiographs. Segmentations were evaluated on 62 radiographs, comparing to manual tracing. Correct identification was obtained for all subjects, and segmentation returned mean  SD values of: Dice coefficient =88  8%; Hausdorff distance =2.1  1.4 mm and; mean surface distance =0.6  0.4 mm. The derived geometric parameters can be used to reduce the amount of manual intervention needed for spine modeling or to measure clinical indices.

Objectives Although magnetic resonance is widely spread to assess qualitatively disc morphology, a simple method to determine reliably intervertebral disc status is still lacking. Shear wave elastography is a novel technique that allows quantitative evaluation of soft-tissues’ mechanical properties. The aim of this study was to assess preliminary the feasibility and reliability of mechanical characterization of cervical intervertebral discs by elastography and to provide first reference values for asymptomatic subjects. Methods Elastographic measurements were performed to determine shear wave speed (SWS) in C6-C7 or C7-T1 disc of 47 subjects; repeatability and inter-operator reproducibility were assessed. Results Global average shear wave speed (SWS) was 3.0 ± 0.4 m/s; measurement repeatability and inter-user reproducibility were 7 and 10 %, respectively. SWS was correlated with both subject’s age (p = 1.3 × 10−5) and body mass index (p = 0.008). Conclusions Shear wave elastography in intervertebral discs proved reliable and allowed stratification of subjects according to age and BMI. Applications could be relevant, for instance, in early detection of disc degeneration or in follow-up after trauma; these results open the way to larger cohort studies to define the place of this technique in routine intervertebral disc assessment. Key Points • A simple method to obtain objectively intervertebral disc status is still lacking • Shear wave elastography was applied in vivo to assess intervertebral discs • Elastography showed promising results in biomechanical disc evaluation • Elastography could be relevant in clinical routine for intervertebral disc assessment The authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling for funding (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Proteor and Covea).