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We present a new Unbiased Minimal Variance (UMV) estimator for the purpose of reconstructing the large--scale structure of the universe from noisy, sparse and incomplete data. Similar to the Wiener Filter (WF), the UMV estimator is derived…

Astrophysics · Physics 2009-10-31 Saleem Zaroubi

Parallel transmission has been a very promising candidate technology to mitigate the inevitable radio-frequency field inhomogeneity in magnetic resonance imaging (MRI) at ultra-high field (UHF). For the first few years, pulse design…

Instrumentation and Detectors · Physics 2013-11-06 Andres Hoyos Idrobo , Pierre Weiss , Aurélien Massire , Alexis Amadon , Nicolas Boulant

We investigated the repeatability of image quality metrics such as SNR, image uniformity, and geometrical distortion at 0.05T over ten days and three sessions per day. The measurements included temperature, humidity, transmit frequency,…

Medical Physics · Physics 2023-04-17 Pavan Poojar Kunal Aggarwal , Marina Manso Jimeno , Sairam Geethanath

Many modern ultrasound beamformers report improved image quality when evaluated using classical criteria like the contrast ratio and contrast-to-noise ratio, which are based on summary statistics of regions of interest (ROIs). However,…

Medical Physics · Physics 2026-02-03 Dongwoon Hyun

Ultrasound tomography (UST) scanners allow quantitative images of the human breast's acoustic properties to be derived with potential applications in screening, diagnosis and therapy planning. Time domain full waveform inversion (TD-FWI) is…

Numerical Analysis · Mathematics 2022-01-19 Felix Lucka , Mailyn Pérez-Liva , Bradley E. Treeby , Ben T. Cox

The spectral signatures of the materials contained in hyperspectral images, also called endmembers (EM), can be significantly affected by variations in atmospheric, illumination or environmental conditions typically occurring within an…

Functional Magnetic Resonance Imaging (fMRI) is a neuroimaging technique with pivotal importance due to its scientific and clinical applications. As with any widely used imaging modality, there is a need to ensure the quality of the same,…

Image and Video Processing · Electrical Eng. & Systems 2020-09-29 David Calhas , Rui Henriques

A new kind of geometric invariants is proposed in this paper, which is called affine weighted moment invariant (AWMI). By combination of local affine differential invariants and a framework of global integral, they can more effectively…

Computer Vision and Pattern Recognition · Computer Science 2017-06-20 Hanlin Mo , You Hao , Shirui Li , Hua Li

This paper focuses on the development of a space-variant regularization model for solving an under-determined linear inverse problem. The case study is a medical image reconstruction from few-view tomographic noisy data. The primary…

Image and Video Processing · Electrical Eng. & Systems 2024-04-29 Elena Morotti , Davide Evangelista , Andrea Sebastiani , Elena Loli Piccolomini

In this paper, we propose a regularization technique for noisy-image super-resolution and image denoising. Total variation (TV) regularization is adopted in many image processing applications to preserve the local smoothness. However, TV…

Image and Video Processing · Electrical Eng. & Systems 2022-02-23 Kaicong Sun , Sven Simon

In this work we present data characterizing the sensitivity of the Bir\'{e}fringence Magnetique du Vide (BMV) instrument. BMV is an experiment attempting to measure vacuum magnetic birefringence (VMB) via the measurement of an ellipticity…

Instrumentation and Detectors · Physics 2018-10-09 M. T. Hartman , A. Rivere , R. Battesti , C. Rizzo

To improve the spatial resolution of power Doppler (PD) imaging, we explored null subtraction imaging (NSI) as an alternative beamforming technique to delay-and-sum (DAS). NSI is a nonlinear beamforming approach that uses three different…

Signal Processing · Electrical Eng. & Systems 2024-04-04 Zhengchang Kou , Matthew Lowerison , Qi You , Yike Wang , Pengfei Song , Michael L. Oelze

Low-field (<1T) magnetic resonance imaging (MRI) scanners remain in widespread use in low- and middle-income countries (LMICs) and are commonly used for some applications in higher income countries e.g. for small child patients with…

Conventional pulse-echo ultrasound suffers when low-cost probes deliver only narrow fractional bandwidths, elongating pulses and erasing high-frequency detail. We address this limitation by learning a data-driven mapping from band-limited…

Signal Processing · Electrical Eng. & Systems 2025-11-06 Sepideh KhakzadGharamaleki , Hassan Rivaz , Brandon Helfield

Mendelian randomization (MR) has become a popular approach to study the effect of a modifiable exposure on an outcome by using genetic variants as instrumental variables. A challenge in MR is that each genetic variant explains a relatively…

Methodology · Statistics 2020-10-13 Ting Ye , Jun Shao , Hyunseung Kang

Accuracy and precision of measurements are important for patient follow up in oncology but, unfortunately, partial volume effects introduce an undesired variability between observers. Super resolution techniques (SR) combine multiple…

Medical Physics · Physics 2015-06-25 Estanislao Oubel , Hubert Beaumont , Antoine Iannessi

Three-dimensional (3D) ultrasound promises various medical applications for abdominal, obstetrics, and breast imaging. However, ultrasound matrix arrays have extremely high element counts limiting their field of view (FOV). Current reduced…

Signal Processing · Electrical Eng. & Systems 2026-04-17 Mick Gardner , Michael L. Oelze

We introduce and demonstrate a new paradigm for quantitative parameter mapping in MRI. Parameter mapping techniques, such as diffusion MRI and quantitative MRI, have the potential to robustly and repeatably measure biologically-relevant…

Image and Video Processing · Electrical Eng. & Systems 2024-11-19 Moucheng Xu , Yukun Zhou , Tobias Goodwin-Allcock , Kimia Firoozabadi , Joseph Jacob , Daniel C. Alexander , Paddy J. Slator

Self-supervised image denoising techniques emerged as convenient methods that allow training denoising models without requiring ground-truth noise-free data. Existing methods usually optimize loss metrics that are calculated from multiple…

This paper considers the regularized estimation of covariance matrices (CM) of high-dimensional (compound) Gaussian data for minimum variance distortionless response (MVDR) beamforming. Linear shrinkage is applied to improve the accuracy…

Signal Processing · Electrical Eng. & Systems 2021-04-06 Lei Xie , Zishu He , Jun Tong , Jun Li , Jiangtao Xi