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Magnetic-resonance-based electrical property mapping using global maxwell tomography with an 8-channel head coil at 7 Tesla: A simulation study

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arXiv 2020年

作者： Giannakopoulos, Ilias I. Serrallés, José E.C. Daniel, Luca Sodickson, Daniel K. Polimeridis, Athanasios G. White, Jacob K. Lattanzi, Riccardo Skoltech Center for Computational Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow143026 Russia Research Laboratory of Electronics Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States Department of Radiology New York University School of Medicine New YorkNY United States Q Bio CA94063 United States

Objective: Global Maxwell Tomography (GMT) is a recently introduced volumetric technique for noninvasive estimation of electrical properties (EP) from magnetic resonance measurements. Previous work evaluated GMT using ideal radiofrequency (RF) excitations. The aim of this simulation study was to assess GMT performance with a realistic RF coil. Methods: We designed a transmit-receive RF coil with 8 decoupled channels for 7T head imaging. We calculated the RF transmit field (B1+) inside heterogeneous head models for different RF shimming approaches, and used them as input for GMT to reconstruct EP for all voxels. Results: Coil tuning/decoupling remained relatively stable when the coil was loaded with different head models. Mean error in EP estimation changed from 7.5% to 9.5% and from 4.8% to 7.2% for relative permittivity and conductivity, respectively, when changing head model without re-tuning the coil. Results slightly improved when an SVD-based RF shimming algorithm was applied, in place of excitation with one coil at a time. Despite errors in EP, RF transmit field (B1+) and absorbed power could be predicted with less than 0.5% error over the entire head. GMT could accurately detect a numerically inserted tumor. Conclusion: This work demonstrates that GMT can reliably reconstruct EP in realistic simulated scenarios using a tailored 8-channel RF coil design at 7T. Future work will focus on construction of the coil and optimization of GMT's robustness to noise, to enable in-vivo GMT experiments. Significance: GMT could provide accurate estimations of tissue EP, which could be used as biomarkers and could enable patient-specific estimation of RF power deposition, which is an unsolved problem for ultrahigh-field magnetic resonance imaging. Copyright © 2020, The Authors. All rights reserved.

关键词： Integral equations

A Fast Volume Integral Equation Solver with Linear Basis Functions for the Accurate Computation of Electromagnetic Fields in MRI

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arXiv 2019年

作者： Georgakis, Ioannis P. Giannakopoulos, Ilias I. Litsarev, Mikhail S. Polimeridis, Athanasios G. Skoltech Center for Computational Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow121205 Russia Q Bio RedwoodCA94063 United States

Objective: This paper proposes a stable volume integral equation (VIE) solver based on polarization/magnetization currents, for the accurate and efficient computation of the electromagnetic scattering from highly inhomogeneous and high contrast objects. Methods: We employ the Galerkin Method of Moments to discretize the formulation with discontinuous piecewise linear basis functions on uniform voxelized grids, allowing for the acceleration of the associated matrix-vector products in an iterative solver, with the help of FFT. Results: Numerical experiments are conducted to study the accuracy and convergence properties of the proposed framework. Their results are compared against standard low order (piecewise constant) discretization schemes, a more conventional VIE formulation based on electric flux densities, and a commercial software package that employs the finite difference time domain method. Conclusion: The results illustrate the superior accuracy and wellconditioned properties of the proposed scheme. Significance: The developed solver can be applied to accurately analyze complex geometries, including realistic human body models, typically used in modeling the interactions between electromagnetic waves and biological tissue, that arise in magnetic resonance scanners. Copyright © 2019, The Authors. All rights reserved.

关键词： Piecewise linear techniques

Medical history predicts phenome-wide disease onset and enables the rapid response to emerging health threats (vol 16, 585, 2025)

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NATURE COMMUNICATIONS 2025年第1期16卷 1-15页

作者： Steinfeldt, Jakob Wild, Benjamin Buergel, Thore Pietzner, Maik Upmeier zu Belzen, Julius Vauvelle, Andre Hegselmann, Stefan Denaxas, Spiros Hemingway, Harry Langenberg, Claudia Landmesser, Ulf Deanfield, John Eils, Roland Department of Cardiology Angiology and Intensive Care Medicine Deutsches Herzzentrum der Charité (DHZC) Berlin Germany Charité – Universitätsmedizin Berlin corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin Klinik/Centrum Berlin Germany Computational Medicine Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany Friede Springer Cardiovascular Prevention Center@Charite Charite - University Medicine Berlin Berlin Germany Institute of Cardiovascular Sciences University College London London UK Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany DZHK (German Centre for Cardiovascular Research) Partner Site Berlin Berlin Berlin Germany MRC Epidemiology Unit Institute of Metabolic Science University of Cambridge Cambridge UK Precision Health University Research Institute Queen Mary University of London and Barts NHS Trust London UK Center for Digital Health Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany Health Data Science Unit Heidelberg University Hospital and BioQuant Heidelberg Germany Institute of Health Informatics University College London London UK British Heart Foundation Data Science Centre London UK Health Data Research UK London UK National Institute for Health Research Biomedical Research Centre at University College London Hospitals London UK Institute for Medical Engineering and Science Massachusetts Institute of Technology Massachusetts USA Pattern Recognition and Image Analysis Lab University of Münster Münster Germany

The COVID-19 pandemic exposed a global deficiency of systematic, data-driven guidance to identify high-risk individuals. Here, we illustrate the utility of routinely recorded medical history to predict the risk for 1741 diseases across clinical specialties and support the rapid response to emerging health threats such as COVID-19. We developed a neural network to learn from health records of 502,489 UK Biobank participants. Importantly, we observed discriminative improvements over basic demographic predictors for 1546 (88.8%) endpoints. After transferring the unmodified risk models to the All of US cohort, we replicated these improvements for 1115 (78.9%) of 1414 investigated endpoints, demonstrating generalizability across healthcare systems and historically underrepresented groups. Ultimately, we showed how this approach could have been used to identify individuals vulnerable to severe COVID-19. Our study demonstrates the potential of medical history to support guidance for emerging pandemics by systematically estimating risk for thousands of diseases at once at minimal cost.

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Tensor completion via gaussian process based initialization

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arXiv 2019年

作者： Kapushev, Yermek Oseledets, Ivan Burnaev, Evgeny Center for Computational and Data-Intensive Science Engineering of Skolkovo Institute of Science and Technology Moscow Russia

In this paper, we consider the tensor completion problem representing the solution in the tensor train (TT) format. It is assumed that tensor is high-dimensional, and tensor values are generated by an unknown smooth function. The assumption allows us to develop an efficient initialization scheme based on Gaussian Process Regression and TT-cross approximation technique. The proposed approach can be used in conjunction with any optimization algorithm that is usually utilized in tensor completion problems. We empirically justify that in this case the reconstruction error improves compared to the tensor completion with random initialization. As an additional benefit, our technique automatically selects rank thanks to using the TT-cross approximation *** Codes 68W25, 65F99, 60G15 Copyright © 2019, The Authors. All rights reserved.

关键词： Tensors

Gaussian polymer chains in a harmonic potential: The path integral approach

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arXiv 2020年

作者： Paradezhenko, G.V. Gascoigne, C. Brilliantov, N.V. Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow121205 Russia Department of Mathematical Sciences University of Bath Claverton Down BathBA2 7AY United Kingdom

We study conformations of the Gaussian polymer chains in d-dimensional space in the presence of an external field with the harmonic potential. We apply a path integral approach to derive an explicit expression for the probability distribution function of the gyration radius. We calculate this function using Monte Carlo simulations and show that our numerical and theoretical results are in a good agreement for different values of the external *** Codes 82D60, 82M31 Copyright © 2020, The Authors. All rights reserved.

关键词： Monte Carlo methods

New lower bound on the rate of traceability set systems

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New lower bound on the rate of traceability set systems

International Symposium on Problems of Redundancy in Information and Control Systems (RED)

作者： Elena Egorova Ilya Vorobyev Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia 127051

In this paper a new lower bound on the rate of IPP set systems with traceability property is proved. The new bound outperforms the previously known bounds.

ISBN: (数字)9781728119441

ISBN: (纸本)9781728119458

In this paper a new lower bound on the rate of IPP set systems with traceability property is proved. The new bound outperforms the previously known bounds.

关键词： Decoding Redundancy Encryption Control systems Hamming distance

Towards Understanding of eSports Athletes' Potentialities: The Sensing System for data Collection and Analysis

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Towards Understanding of eSports Athletes' Potentialities: T...

Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, UIC-ATC

作者： Alexander Korotin Nikita Khromov Anton Stepanov Andrey Lange Evgeny Burnaev Andrey Somov Center for Computational and Data-Intensive Science and Engineering (CDISE) Skolkovo Institute of Science and Technology Moscow Russia

ISBN: (数字)9781728140346

ISBN: (纸本)9781728140353

eSports is a developing multidisciplinary research area. At present, there is a lack of relevant data collected from real eSports athletes and lack of platforms which could be used for the data collection and further analysis. In this paper, we present a sensing system for enabling the data collection from professional athletes. Also, we report on the case study about collecting and analyzing the gaze data from Monolith professional eSports team specializing in Counter-Strike: Global Offensive (CS:GO) discipline. We perform a comparative study on assessing the gaze of amateur players and professional athletes. The results of our work are vital for ensuring eSports data collection and the following analysis in the scope of scouting or assessing the eSports players and athletes.

关键词： Games Sensors Measurement data collection Weapons Mice Affective computing

Trivariate Lifted Codes with Disjoint Repair Groups

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Trivariate Lifted Codes with Disjoint Repair Groups

International Symposium on Problems of Redundancy in Information and Control Systems (RED)

作者： Nikita Polyanskii Ilya Vorobyev Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia 121205

ISBN: (数字)9781728119441

ISBN: (纸本)9781728119458

Guo, Kopparty, and Sudan introduced the notion of lifted Reed-Solomon codes in the context of locally correctable codes. We continue the study of lifted codes with the application for so-called t-disjoint-repair-group property (t-DRGP) codes. A code is said to have the t-DRGP if every symbol in a codeword from the code has t mutually disjoint recovering sets of coordinates in the codeword. In some parameter regimes, our proposed t-DRGP codes based on lifted codes have lower redundancy than previously known t-DRGP codes.

关键词： Redundancy Upper bound Control systems Maintenance engineering Reed-Solomon codes Frequency modulation

Sensors and Game Synchronization for data Analysis in eSports

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Sensors and Game Synchronization for Data Analysis in eSport...

IEEE International Conference on Industrial Informatics (INDIN)

作者： Anton Stepanov Andrey Lange Nikita Khromov Alexander Korotin Evgeny Burnaev Andrey Somov Center for Computational and Data-Intensive Science and Engineering (CDISE) Skolkovo Institute of Science and Technology Moscow Russia

eSports industry has greatly progressed within the last decade in terms of audience and fund rising, broadcasting, networking and hardware. Since the number and quality of professional team has evolved too, there is a reasonable need in improving skills and training process of professional eSports athletes. In this work, we demonstrate a system able to collect heterogeneous data (physiological, environmental, video, telemetry) and guarantying synchronization with 10 ms accuracy. In particular, we demonstrate how to synchronize various sensors and ensure post synchronization, i.e. logged video, a so-called demo file, with the sensors data. Our experimental results achieved on the CS:GO game discipline show up to 3 ms accuracy of the time synchronization of the gaming computer.

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