Reduced order modelling using neural networks for predictive modelling of 3d-magneto-mechanical problems with application to magnetic resonance imaging scanners

The design of magnets for magnetic resonance imaging (MRI) scanners requires the numerical simulation of a coupled magneto-mechanical system where the effects that different material parameters and in-service loading conditions have on both imaging and MRI performance are key to aid with the design and the manufacturing process. To correctly capture the complex physics, and to obtain accurate solutions, finite element simulations with dense meshes and high order elements are needed. Reduced order model approaches, based on the established proper orthogonal decomposition (POD) approach, are attractive as they can rapidly predict the numerical simulations needed under changing parameters or conditions. However, the projected (PODP) approach has an invasive computational implementation, whilst the interpolated (PODI) approach presents challenges when the dimension of the space of parameters to be investigated becomes large. As an alternative, we investigate a POD technique based on using a neural network regression, which is not as invasive as PODP, but has superior approximation properties compared to PODI. We apply this to the coupled magneto-mechanical system to understand three pressing industrial problems: firstly, the accurate and rapid computation of the resonant frequencies associated with this coupled magneto-mechanical system, secondly, the effects of magnet motion on the Ohmic power and kinetic energy curves, and, thirdly, the prediction of the uncertainty in Ohmic power and kinetic energy curves as a function of exciting frequency for uncertain material parameters

Left Ventricular Diastolic Function in Healthy Adult Individuals: Results of the World Alliance Societies of Echocardiography Normal Values Study

Background: The World Alliance Societies of Echocardiography (WASE) study was conducted to describe echocardiographic normal values in adults and to compare races and nationalities using a uniform acquisition and measurement protocol. This report focuses on left ventricular (LV) diastolic function. Methods: WASE is an international, cross-sectional study. Participants were enrolled with equal distribution according to age and gender. Echocardiograms were analyzed in a core laboratory based on the latest American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines. Left ventricular diastolic function was assessed by E, E/A, e' velocities, E/e', left atrial volume index (LAVI), and tricuspid regurgitation velocity. Determination of LV diastolic function was made using the algorithm proposed by the guidelines. Results: A total of 2,008 subjects from 15 countries were enrolled. The majority were of white or Asian race (42.8%, 41.8%, respectively). E and E/e' were higher in female patients, while LAVI was similar in both genders. Consistent increase in E/e' and decrease in E/A, E, and e' were found as age increased. The upper limit of normal for LAVI was higher in WASE compared with the guidelines. The lower limits of normal for e' were smaller in elder groups than those in the guidelines, while the upper limits of normal for E/e' were below the guideline values. These findings suggest that the cutoff value for LAVI should be shifted upward and age-specific cutoff values for e' should be considered. In WASE, <93.6% of patients were classified as normal LV diastolic function using the guidelines' algorithm, and the proportion increased to 97.4% when applying the revised cutoff values for LAVI obtained in our study. Conclusions: Guideline-recommended normal values for e' velocities and LAVI should be reconsidered. The algorithm for the determination of LV diastolic function proposed by the guidelines is useful, but adjustments to LAVI could further improve it

Left Ventricular Diastolic Function in Healthy Adult Individuals: Results of the World Alliance Societies of Echocardiography Normal Values Study

Background: The World Alliance Societies of Echocardiography (WASE) study was conducted to describe echocardiographic normal values in adults and to compare races and nationalities using a uniform acquisition and measurement protocol. This report focuses on left ventricular (LV) diastolic function. Methods: WASE is an international, cross-sectional study. Participants were enrolled with equal distribution according to age and gender. Echocardiograms were analyzed in a core laboratory based on the latest American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines. Left ventricular diastolic function was assessed by E, E/A, e' velocities, E/e', left atrial volume index (LAVI), and tricuspid regurgitation velocity. Determination of LV diastolic function was made using the algorithm proposed by the guidelines. Results: A total of 2,008 subjects from 15 countries were enrolled. The majority were of white or Asian race (42.8, 41.8, respectively). E and E/e' were higher in female patients, while LAVI was similar in both genders. Consistent increase in E/e' and decrease in E/A, E, and e' were found as age increased. The upper limit of normal for LAVI was higher in WASE compared with the guidelines. The lower limits of normal for e' were smaller in elder groups than those in the guidelines, while the upper limits of normal for E/e' were below the guideline values. These findings suggest that the cutoff value for LAVI should be shifted upward and age-specific cutoff values for e' should be considered. In WASE, <93.6 of patients were classified as normal LV diastolic function using the guidelines' algorithm, and the proportion increased to 97.4 when applying the revised cutoff values for LAVI obtained in our study. Conclusions: Guideline-recommended normal values for e' velocities and LAVI should be reconsidered. The algorithm for the determination of LV diastolic function proposed by the guidelines is useful, but adjustments to LAVI could further improve it. © 2020 American Society of Echocardiograph