Purpose: Magnitude-based fitting of chemical shift-encoded data enables proton density fat fraction (PDFF) and estimation where complex-based methods fail or when phase data are inaccessible or unreliable. However, traditional magnitude-based fitting algorithms do not account for Rician noise, creating a source of bias. To address these issues, we propose an algorithm for magnitude-only PDFF and estimation with Rician noise modeling (MAGORINO).
Methods: Simulations of multi-echo gradient-echo signal intensities are used to investigate the performance and behavior of MAGORINO over the space of clinically plausible PDFF, , and SNR values. Fitting performance is assessed through detailed simulation, including likelihood function visualization, and in a multisite, multivendor, and multi-field-strength phantom data set and in vivo.
Results: Simulations show that Rician noise-based magnitude fitting outperforms existing Gaussian noise-based fitting and reveals two key mechanisms underpinning the observed improvement. First, the likelihood functions exhibit two local optima; Rician noise modeling increases the chance that the global optimum corresponds to the ground truth. Second, when the global optimum corresponds to ground truth for both noise models, the optimum from Rician noise modeling is closer to ground truth. Multisite phantom experiments show good agreement of MAGORINO PDFF with reference values, and in vivo experiments replicate the performance benefits observed in simulation.
Conclusion: The MAGORINO algorithm reduces Rician noise-related bias in PDFF and estimation, thus addressing a key limitation of existing magnitude-only fitting methods. Our results offer insight into the importance of the noise model for selecting the correct optimum when multiple plausible optima exist.
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http://dx.doi.org/10.1002/mrm.29493 | DOI Listing |
bioRxiv
December 2024
Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States.
Evaluating tissue microstructure and membrane integrity in the living human brain through diffusion-water exchange imaging is challenging due to requirements for a high signal-to-noise ratio and short diffusion times dictated by relatively fast exchange processes. The goal of this work was to demonstrate the feasibility of imaging of tissue micro-geometries and water exchange within the brain gray matter using the state-of-the-art Connectome 2.0 scanner equipped with an ultra-high-performance gradient system (maximum gradient strength=500 mT/m, maximum slew rate=600 T/m/s).
View Article and Find Full Text PDFMed Phys
December 2024
Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China.
Background: Magnetic resonance imaging (MRI) is a crucial technique for both scientific research and clinical diagnosis. However, noise generated during MR data acquisition degrades image quality, particularly in hyperpolarized (HP) gas MRI. While deep learning (DL) methods have shown promise for MR image denoising, most of them fail to adequately utilize the long-range information which is important to improve denoising performance.
View Article and Find Full Text PDFPhys Med Biol
November 2024
Department of Computer Science & Engineering, Punjabi University, Chandigarh Road, Patiala 147002, Punjab, India.
Magnetic resonance imaging (MRI) provides detailed structural information of the internal body organs and soft tissue regions of a patient in clinical diagnosis for disease detection, localization, and progress monitoring. MRI scanner hardware manufacturers incorporate various post-acquisition image-processing techniques into the scanner's computer software tools for different post-processing tasks. These tools provide a final image of adequate quality and essential features for accurate clinical reporting and predictive interpretation for better treatment planning.
View Article and Find Full Text PDFJ Alzheimers Dis
November 2024
Faculty of Engineering, University Malaysia Sarawak, Kuching, Malaysia.
Background: Degradation of magnetic resonance imaging (MRI) remains a challenging issue, with noise being a key damaging component introduced due to a variety of environmental and mechanical factors.
Objective: The aim of this research work is to addresses the issue of noise reduction and to predict Alzheimer's disease detection efficiently.
Methods: First, we present a genetic programming (GP) technique for reducing Rician noise in MRI images to pre-process the dataset.
Invest Radiol
October 2024
From the Department of Radiology, University of Wisconsin-Madison, Madison, WI (R.A.V., D.T., J.R., S.B.R.); Department of Radiology and Nuclear Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands (R.A.V.); Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI (L.M.); Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI (J.R.); Department of Medical Physics, University of Wisconsin-Madison, Madison, WI (S.B.R.); Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI (S.B.R.); Department of Medicine, University of Wisconsin-Madison, Madison, WI (S.B.R.); and Department of Emergency Medicine, University of Wisconsin-Madison, Madison, WI (S.B.R.).
Objectives: Ferumoxytol is a superparamagnetic iron-oxide product that is increasingly used off-label for contrast-enhanced magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). With the recent regulatory approval of generic ferumoxytol, there may be an opportunity to reduce cost, so long as generic ferumoxytol has similar imaging performance to brand name ferumoxytol. This study aims to compare the relaxation-concentration dependence and MRI performance of brand name ferumoxytol with generic ferumoxytol through phantom and in vivo experiments.
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