Motion corrected 3D reconstruction of the fetal thorax from prenatal MRI

In this paper we present a semi-automatic method for analysis of the fetal thorax in genuine three-dimensional volumes. After one initial click we localize the spine and accurately determine the volume of the fetal lung from high resolution volumetric images reconstructed from motion corrupted prenatal Magnetic Resonance Imaging (MRI). We compare the current state-of-the-art method of segmenting the lung in a slice-by-slice manner with the most recent multi-scan reconstruction methods. We use fast rotation invariant spherical harmonics image descriptors with Classification Forest ensemble learning methods to extract the spinal cord and show an efficient way to generate a segmentation prior for the fetal lung from this information for two different MRI field strengths. The spinal cord can be segmented with a DICE coefficient of 0.89 and the automatic lung segmentation has been evaluated with a DICE coefficient of 0.87. We evaluate our method on 29 fetuses with a gestational age (GA) between 20 and 38 weeks and show that our computed segmentations and the manual ground truth correlate well with the recorded values in literature

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Analyse micromécanique de la rupture des composites céramiques

The fracture mechanic analysis of a basic ceramic-ceramic composite (filament + coating) is based on two main assumptions : local adaptation by sliding between fibre and matrix when a crack in the matrix appears, and statistical distribution of defects. The consequences of such assumptions concerning the multicracking of the matrix explain the non linear behaviour of such composites. They are discussed in relation with experimental results obtained on unidirectional multifilaments SiC/alumina composites.L'analyse mécanique du comportement à la rupture d'un composite céramique/céramique élémentaire constitué d'une fibre gainée de matrice s'appuie sur deux hypothèses essentielles : d'une part l'adaptation locale par glissement fibre-matrice à l'apparition d'une fissure matricielle, et d'autre part la distribution statistique de défauts. Les conséquences de ces hypothèses sur la multifissuration matricielle, sur les comportements non linéaires des composites monofilamentaires sont discutées au regard des résultats expérimentaux sur composites unidirectionnels multifilamentaires SiC/alumine

Automatic segmentation of ante-natal 3D ultrasound images

International audience<p>The development of 3D ultrasonic probes and 3D ultrasound imaging offersnew functionalities that call for specific image processingdevelopments. In this paper, we propose an original method for thesegmentationof the utero-fetal unit (UFU) from 3D ultrasound (3DUS) volumes, acquired during the first trimester of gestation.UFU segmentation is required for a number of tasks, such as precise organ delineation, 3D modeling, quantitative measurements and evaluation of the clinical impact of 3D imaging.The segmentation problem is formulated as the optimization of a partition of theimage into two classes of tissues: the amniotic fluid and the fetaltissues. A Bayesian formulation of the partition problem integrates statistical models of theintensity distributions in each tissue class as homogeneity constraints and regularity constraints on the contours.An energy functional is minimized using a level set implementation of a deformable model to identify the optimal partition. We propose to combine Rayleigh, Normal, Exponential and Gamma distribution models to compute the region homogeneity constraints.We tested the segmentation method on a database of 19 ante-natal 3DUS images. Promising results wereobtained, showing the flexibility of the level set formulation and the interest of learning the most appropriatestatistical models according to the idiosyncrasies of the data and the tissues. The segmentation method was shown to be robust to different types of initialization and to provide accurate results, with an average overlap measure of 0.89 when comparing with manual segmentations.</p