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Noise characterization in MRI has multiple applications, including quality assurance and protocol optimization. It is particularly important in the presence of parallel imaging acceleration, where the noise distribution can contain severe…

In fMRI, capturing brain activation during a task is dependent on how quickly k-space arrays are obtained. Acquiring full k-space arrays, which are reconstructed into images using the inverse Fourier transform (IFT), that make up volume…

Applications · Statistics 2024-05-27 Chase J Sakitis , Daniel B Rowe

Purpose: To develop a scan-specific model that estimates and corrects k-space errors made when reconstructing accelerated Magnetic Resonance Imaging (MRI) data. Methods: Scan-Specific Artifact Reduction in k-space (SPARK) trains a…

Signal Processing · Electrical Eng. & Systems 2022-04-29 Yamin Arefeen , Onur Beker , Jaejin Cho , Heng Yu , Elfar Adalsteinsson , Berkin Bilgic

k-space undersampling is a standard technique to accelerate MR image acquisitions. Reconstruction techniques including GeneRalized Autocalibrating Partial Parallel Acquisition(GRAPPA) and its variants are utilized extensively in clinical…

Image and Video Processing · Electrical Eng. & Systems 2021-02-17 Nader Tavaf , Amirsina Torfi , Kamil Ugurbil , Pierre-Francois Van de Moortele

In high-dimensional magnetic resonance imaging applications, time-consuming, sequential acquisition of data samples in the spatial frequency domain ($k$-space) can often be accelerated by accounting for dependencies along imaging dimensions…

Image and Video Processing · Electrical Eng. & Systems 2017-10-24 Evan Levine , Brian Hargreaves

This paper considers the problem of undersampled MRI reconstruction. We propose a novel Transformer-based framework for directly processing signal in k-space, going beyond the limitation of regular grids as ConvNets do. We adopt an implicit…

Image and Video Processing · Electrical Eng. & Systems 2022-11-11 Ziheng Zhao , Tianjiao Zhang , Weidi Xie , Yanfeng Wang , Ya Zhang

Purpose: Noise resilience in image reconstructions by scan-specific robust artificial neural networks for k-space interpolation (RAKI) is linked to nonlinear activations in k-space. To gain a deeper understanding of this relationship, an…

Computer Vision and Pattern Recognition · Computer Science 2025-05-12 Peter Dawood , Felix Breuer , Istvan Homolya , Maximilian Gram , Peter M. Jakob , Moritz Zaiss , Martin Blaimer

MRI data is acquired in Fourier space/k-space. Data acquisition is typically performed on a Cartesian grid in this space to enable the use of a fast Fourier transform algorithm to achieve fast and efficient reconstruction. However, it has…

Signal Processing · Electrical Eng. & Systems 2024-01-17 Daniel Abraham , Mark Nishimura , Xiaozhi Cao , Congyu Liao , Kawin Setsompop

Purpose: Pushing MRI speed further demands more spatially-encoded information captured per unit time, e.g., by superimposing additional field modulations during oversampled readout. However, this can introduce calibration errors and…

Medical Physics · Physics 2026-01-12 Rui Tian , Martin Uecker , Oliver Holder , Pavel Povolni , Theodor Steffen , Klaus Scheffler

Deep learning has been successfully demonstrated in MRI reconstruction of accelerated acquisitions. However, its dependence on representative training data limits the application across different contrasts, anatomies, or image sizes. To…

Signal Processing · Electrical Eng. & Systems 2019-09-20 Chaoping Zhang , Florian Dubost , Marleen de Bruijne , Stefan Klein , Dirk H. J. Poot

In Magnetic Resonance Imaging (MRI) data samples are collected in the spatial frequency domain (k-space), typically by time-consuming line-by-line scanning on a Cartesian grid. Scans can be accelerated by simultaneous acquisition of data…

Medical Physics · Physics 2015-03-24 Vivek Athalye , Michael Lustig , Martin Uecker

Most existing MRI reconstruction methods perform tar-geted reconstruction of the entire MR image without tak-ing specific tissue regions into consideration. This may fail to emphasize the reconstruction accuracy on im-portant tissues for…

Image and Video Processing · Electrical Eng. & Systems 2023-09-06 Yu Guan , Chuanming Yu , Shiyu Lu , Zhuoxu Cui , Dong Liang , Qiegen Liu

Accelerating magnetic resonance imaging (MRI) remains challenging, particularly under realistic acquisition noise. While diffusion models have recently shown promise for reconstructing undersampled MRI data, many approaches lack an explicit…

Image and Video Processing · Electrical Eng. & Systems 2026-02-06 Nikola Janjušević , Amirhossein Khalilian-Gourtani , Yao Wang , Li Feng

Purpose: Interpretability is essential for the clinical adoption of state-of-the-art machine learning (ML) methods in magnetic resonance imaging (MRI). Conventional evaluation of ML reconstructions relies heavily on aggregate image metrics…

High-resolution magnetic resonance imaging (MRI) is essential in clinical diagnosis. However, its long acquisition time remains a critical issue. Parallel imaging (PI) is a common approach to reduce acquisition time by periodically skipping…

Image and Video Processing · Electrical Eng. & Systems 2025-06-10 Hao Li , Yusheng Zhou , Jianan Liu , Xiling Liu , Tao Huang , Zhihan Lyu , Weidong Cai , Wei Chen

Accurately representing the sound field with the high spatial resolution is critical for immersive and interactive sound field reproduction technology. To minimize experimental effort, data-driven methods have been proposed to estimate…

Audio and Speech Processing · Electrical Eng. & Systems 2023-11-10 Zining Liang , Wen Zhang , Thushara D. Abhayapala

Knowledge of the noise distribution in diffusion MRI is the centerpiece to quantify uncertainties arising from the acquisition process. Accurate estimation beyond textbook distributions often requires information about the acquisition…

Image and Video Processing · Electrical Eng. & Systems 2020-07-07 Samuel St-Jean , Alberto De Luca , Chantal M. W. Tax , Max A. Viergever , Alexander Leemans

Accelerated MRI reconstruction involves solving an ill-posed inverse problem where noise in acquired data propagates to the reconstructed images. Noise analyses are central to MRI reconstruction for providing an explicit measure of solution…

Computer Vision and Pattern Recognition · Computer Science 2025-05-06 Onat Dalmaz , Arjun D. Desai , Reinhard Heckel , Tolga Çukur , Akshay S. Chaudhari , Brian A. Hargreaves

Purpose: To develop a fast, general-purpose framework for voxelwise noise characterization in linear and nonlinear iterative MRI reconstructions, recovering the image-domain noise variance from which SNR, $g$-factor, and related…

Signal Processing · Electrical Eng. & Systems 2026-05-12 Onat Dalmaz , Daniel Abraham , Alexander R. Toews , Akshay S. Chaudhari , Kawin Setsompop , Brian A. Hargreaves

Weak lensing observations measure the shear field and hence the gradient of the dimensionless surface density $\kappa$. We present several new algorithms to recover $\kappa$ {}from shear estimates on a finite region and compare how they…

Astrophysics · Physics 2009-10-28 Gordon Squires , Nick Kaiser
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