Evidence map›Paper›PMID 40762133›Full record

ArticleMagnetic resonance in medicine2025

Image space formalism of convolutional neural networks for k-space interpolation.

P Dawood, F Breuer, M Gram, I Homolya, P M Jakob, M Zaiss, M Blaimer

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Article in Magnetic resonance in medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

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3citing papers in PubMed
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1 · What the graph read from it

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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

7 authors.

P DawoodExperimental Physics 5, University of Würzburg, Würzburg, Germany.ORCID https://orcid.org/0000-0001-7127-607X
F BreuerMagnetic Resonance and X-ray Imaging Department, Fraunhofer Institute for Integrated Circuits IIS, Division Development Center X-Ray Technology, Würzburg, Germany.
M GramExperimental Physics 5, University of Würzburg, Würzburg, Germany.ORCID https://orcid.org/0000-0003-2184-3325
I HomolyaMolecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.ORCID https://orcid.org/0000-0002-0662-6464
P M JakobExperimental Physics 5, University of Würzburg, Würzburg, Germany.ORCID https://orcid.org/0000-0002-3481-5545
M ZaissInstitute of Neuroradiology, University Hospital Erlangen, Erlangen, Germany.ORCID https://orcid.org/0000-0001-9780-3616
M BlaimerMagnetic Resonance and X-ray Imaging Department, Fraunhofer Institute for Integrated Circuits IIS, Division Development Center X-Ray Technology, Würzburg, Germany.ORCID https://orcid.org/0000-0002-6360-9871

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeNoise 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 image space formalism of RAKI is introduced for analyzing noise propagation analytically, identifying and characterizing image reconstruction features and to describe the role of nonlinear activations in a human-readable manner. THEORY AND

methodsThe image space formalism for RAKI inference is employed by expressing nonlinear activations in k-space as element-wise multiplications with activation masks, which transform into convolutions in image space. Jacobians of the de-aliased, coil-combined image relative to the aliased coil images can be expressed algebraically; thus, the noise amplification is quantified analytically (g-factor maps). We analyze the role of nonlinearity for noise resilience by controlling the degree of nonlinearity in the reconstruction model via the negative slope parameter in leaky ReLU.

resultsThe analytical g-factor maps correspond with those obtained from Monte Carlo simulations and from an auto differentiation approach for in vivo brain images. Apparent blurring and contrast loss artifacts are identified as implications of enhanced noise resilience. These residual artifacts can be traded against noise resilience by adjusting the degree of nonlinearity in the model (Tikhonov-like regularization) in case of limited training data. The inspection of image space activations reveals an autocorrelation pattern leading to a potential center artifact.

conclusionThe image space formalism of RAKI provides the means for analytical quantitative noise-propagation analysis and human-readable visualization of the effects of the nonlinear activation functions in k-space.

Indexed as

BrainImage Processing, Computer-AssistedMagnetic Resonance ImagingNeural Networks, ComputerAlgorithmsComputer SimulationConvolutional Neural NetworksHumansMonte Carlo MethodPhantoms, ImagingSignal-To-Noise Ratioconvolutional neural networkexplainable AIg‐factorGRAPPAnoise propagationparallel imagingRAKI

Identifiers

PMID40762133
PMCPMC12501693

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.