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The eikonal equation has become an indispensable tool for modeling cardiac electrical activation accurately and efficiently. In principle, by matching clinically recorded and eikonal-based electrocardiograms (ECGs), it is possible to build…

Optimization and Control · Mathematics 2023-12-06 Thomas Grandits , Jan Verhülsdonk , Gundolf Haase , Alexander Effland , Simone Pezzuto

In image reconstruction, an accurate quantification of uncertainty is of great importance for informed decision making. Here, the Bayesian approach to inverse problems can be used: the image is represented through a random function that…

Numerical Analysis · Mathematics 2025-04-24 Jonas Latz , Aretha L. Teckentrup , Simon Urbainczyk

Solving inverse problems in cardiac electrophysiology consists in the recovery of physiological parameters from surface electrocardiogram (ECG) measurements, a task which is often computationally unfeasible due to the severe ill-posedness…

Numerical Analysis · Mathematics 2026-05-05 Edoardo Centofanti , Giovanni Ziarelli , Simone Scacchi , Luca Franco Pavarino

The reconstruction of the structure of biological tissue using electromyographic data is a non-invasive imaging method with diverse medical applications. Mathematically, this process is an inverse problem. Furthermore, electromyographic…

Numerical Analysis · Mathematics 2021-05-26 Anna Rörich , Tim A. Werthmann , Dominik Göddeke , Lars Grasedyck

A major challenge in X-ray computed tomography (CT) is reducing radiation dose while maintaining high quality of reconstructed images. To reduce the radiation dose, one can reduce the number of projection views (sparse-view CT); however, it…

Machine Learning · Statistics 2019-09-17 Xuehang Zheng , Il Yong Chun , Zhipeng Li , Yong Long , Jeffrey A. Fessler

An important paradigm in smart health is developing diagnosis tools and monitoring a patient's heart activity through processing Electrocardiogram (ECG) signals is a key example, sue to high mortality rate of heart-related disease. However,…

Signal Processing · Electrical Eng. & Systems 2018-11-02 Jiaming Chen , Ali Valehi , Abolfazl Razi

In electroencephalography (EEG) source imaging, the inverse source estimates are depth biased in such a way that their maxima are often close to the sensors. This depth bias can be quantified by inspecting the statistics (mean and…

Medical Physics · Physics 2025-07-04 Alexandra Koulouri , Ville Rimpiläinen , Mike Brookes , Jari P Kaipio

Airborne electromagnetic surveys may consist of hundreds of thousands of soundings. In most cases, this makes 3D inversions unfeasible even when the subsurface is characterized by a high level of heterogeneity. Instead, approaches based on…

Geophysics · Physics 2021-09-29 Peng Bai , Giulio Vignoli , Thomas Mejer Hansen

Computer-based simulations of non-invasive cardiac electrical outputs, such as electrocardiograms and body surface potential maps, usually entail severe computational costs due to the need of capturing fine-scale processes and to the…

Numerical Analysis · Mathematics 2023-08-09 Elena Zappon , Andrea Manzoni , Alfio Quarteroni

Electrical impedance tomography (EIT) is an imaging modality in which the conductivity distribution inside a target is reconstructed based on voltage measurements from the surface of the target. Reconstructing the conductivity distribution…

Mathematical Physics · Physics 2012-07-05 Antti Lipponen , Aku Seppänen , Jari Kaipio

The horseshoe prior is known to possess many desirable properties for Bayesian estimation of sparse parameter vectors, yet its density function lacks an analytic form. As such, it is challenging to find a closed-form solution for the…

Machine Learning · Statistics 2022-11-08 Shu Yu Tew , Daniel F. Schmidt , Enes Makalic

This paper proposes a new approach for solving ill-posed nonlinear inverse problems. For ease of explanation of the proposed approach, we use the example of lung electrical impedance tomography (EIT), which is known to be a nonlinear and…

Numerical Analysis · Mathematics 2019-08-01 Jin Keun Seo , Kang Cheol Kim , Ariungerel Jargal , Kyounghun Lee , Bastian Harrach

EEG foundation models achieve state-of-the-art clinical performance, yet the internal computations driving their predictions remain opaque: a barrier to clinical trust. We apply TopK Sparse Autoencoders (SAEs) across three architecturally…

This work aims efficiently estimating the posterior distribution of kinetic parameters for dynamic positron emission tomography (PET) imaging given a measurement of time of activity curve. Considering the inherent information loss from…

Medical Physics · Physics 2023-10-25 Xiaofeng Liu , Thibault Marin , Tiss Amal , Jonghye Woo , Georges El Fakhri , Jinsong Ouyang

Exponential random graph models (ERGMs) are flexible probabilistic frameworks to model statistical networks through a variety of network summary statistics. Conventional Bayesian estimation for ERGMs involves iteratively exchanging with an…

Methodology · Statistics 2025-04-15 Yefeng Fan , Simon White

We propose Bayesian methods for Gaussian graphical models that lead to sparse and adaptively shrunk estimators of the precision (inverse covariance) matrix. Our methods are based on lasso-type regularization priors leading to parsimonious…

Methodology · Statistics 2013-10-07 Rajesh Talluri , Veerabhadran Baladandayuthapani , Bani K. Mallick

Electrocardiographic imaging (ECGI) aims to non-invasively reconstruct activation maps of the heart from temporal body surface potentials. While most existing approaches rely on inverse and optimization techniques that may yield…

Methodology · Statistics 2025-09-25 Emma Lagracie , Luc de Montella

In computational inverse problems, it is common that a detailed and accurate forward model is approximated by a computationally less challenging substitute. The model reduction may be necessary to meet constraints in computing time when…

Methodology · Statistics 2018-02-14 Daniela Calvetti , Matthew M. Dunlop , Erkki Somersalo , Andrew M. Stuart

Inverse imaging problems that are ill-posed can be encountered across multiple domains of science and technology, ranging from medical diagnosis to astronomical studies. To reconstruct images from incomplete and distorted data, it is…

Image and Video Processing · Electrical Eng. & Systems 2023-11-30 Cesar F. Caiafa , Ramiro M. Irastorza

These days we live in a world with a permanent electromagnetic field. This raises many questions about our health and the deployment of new equipment. The problem is that these fields remain difficult to visualize easily, which only some…

Signal Processing · Electrical Eng. & Systems 2022-03-04 Angesom Ataklity Tesfay , Laurent Clavier