journal
https://read.qxmd.com/read/38029371/uncertainty-propagation-in-absolute-metabolite-quantification-for-in-vivo-mrs-of-the-human-brain
#1
JOURNAL ARTICLE
Ronald Instrella, Christoph Juchem
PURPOSE: Absolute spectral quantification is the standard method for deriving estimates of the concentration from metabolite signals measured using in vivo proton MRS (1 H-MRS). This method is often reported with minimum variance estimators, specifically the Cramér-Rao lower bound (CRLB) of the metabolite signal amplitude's scaling factor from linear combination modeling. This value serves as a proxy for SD and is commonly reported in MRS experiments. Characterizing the uncertainty of absolute quantification, however, depends on more than simply the CRLB...
November 29, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38013217/dynamic-t-2-relaxometry-of-hyperpolarized-1-13-c-pyruvate-mri-in-the-human-brain-and-kidneys
#2
JOURNAL ARTICLE
Xiaoxi Liu, Di Cui, Duan Xu, Robert Bok, Zhen J Wang, Daniel B Vigneron, Peder E Z Larson, Jeremy W Gordon
PURPOSE: This study aimed to quantify <mml:math xmlns:mml="https://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msubsup><mml:mi>T</mml:mi> <mml:mn>2</mml:mn> <mml:mo>*</mml:mo></mml:msubsup> </mml:mrow> <mml:annotation>$$ {T}_2^{\ast } $$</mml:annotation></mml:semantics> </mml:math> for hyperpolarized [1-13 C]pyruvate and metabolites in the healthy human brain and renal cell carcinoma (RCC) patients at 3 T...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38013214/minimization-of-eddy-power-loss-in-the-cryostat-for-a-z-gradient-array-coil-driven-by-an-arbitrary-pulse-sequence-an-electromagnetic-approach
#3
JOURNAL ARTICLE
Manouchehr Takrimi, Ergin Atalar
PURPOSE: This paper presents a novel computational approach to optimize gradient array performance for a given pulse sequence. Specifically, we propose an electromagnetic (EM) approach that minimizes eddy losses within the cryostat while maintaining key performance parameters such as field linearity, gradient strength, and imaging region's dimension and position. METHODS: High-resolution EM simulations on the cryostat's surface are deployed to compute the net EM fields generated by each element of a gradient array coil at different frequencies...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38013206/feasibility-of-dynamic-t-2-based-oxygen-enhanced-lung-mri-at-3t
#4
JOURNAL ARTICLE
Mina Kim, Josephine H Naish, Sarah H Needleman, Marta Tibiletti, Yohn Taylor, James P B O'Connor, Geoff J M Parker
PURPOSE: To demonstrate proof-of-concept of a T2 *-sensitized oxygen-enhanced MRI (OE-MRI) method at 3T by assessing signal characteristics, repeatability, and reproducibility of dynamic lung OE-MRI metrics in healthy volunteers. METHODS: We performed sequence-specific simulations for protocol optimisation and acquired free-breathing OE-MRI data from 16 healthy subjects using a dual-echo RF-spoiled gradient echo approach at 3T across two institutions. Non-linear registration and tissue density correction were applied...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38010083/optimization-of-the-flip-angles-of-narrow-band-editing-pulses-in-j-difference-edited-mrs-of-lactate-at-3t
#5
JOURNAL ARTICLE
Jason E Moore, Ryan K Robison, Jie Hu, Saikat T Sengupta, Olaimatu S Mahdi, Adam W Anderson, Leo Y Luo, Alexander C Mohler, Ryan T Merrell, Changho Choi
PURPOSE: Application of highly selective editing RF pulses provides a means of minimizing co-editing of contaminants in J-difference MRS (MEGA), but it causes reduction in editing yield. We examined the flip angles (FAs) of narrow-band editing pulses to maximize the lactate edited signal with minimal co-editing of threonine. METHODS: The effect of editing-pulse FA on the editing performance was examined, with numerical and phantom analyses, for bandwidths of 17...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38010072/radiation-damping-at-clinical-field-strength-characterization-and-compensation-in-quantitative-measurements
#6
JOURNAL ARTICLE
Niklas Wallstein, Roland Müller, André Pampel, Harald E Möller
PURPOSE: In any MR experiment, the bulk magnetization acts on itself, caused by the induced current in the RF receiver circuit that generates an oscillating damping field. This effect, known as "radiation damping" (RD), is usually weak and, therefore, unconsidered in MRI, but can affect quantitative studies performed with dedicated coils that provide a high SNR. The current work examined RD in a setup for investigations of small tissue specimens including a quantitative characterization of the spin-coil system...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38010065/accelerating-spiral-deblurring-with-square-kernels-and-low-pass-preconditioning
#7
JOURNAL ARTICLE
Dinghui Wang, Tzu Cheng Chao, James G Pipe
PURPOSE: Robust implementation of spiral imaging requires efficient deblurring. A deblurring method was previously proposed to separate and deblur water and fat simultaneously, based on image-space kernel operations. The goal of this work is to improve the performance of the previous deblurring method using kernels with better properties. METHODS: Four types of kernels were formed using different models for the region outside the collected k-space as well as low-pass preconditioning (LP)...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38010053/myelin-water-imaging-at-0-55-t-using-a-multigradient-echo-sequence
#8
JOURNAL ARTICLE
Jessica Schäper, Oliver Bieri
PURPOSE: To investigate the prospects of a multigradient-echo (mGRE) acquisition for in vivo myelin water imaging at 0.55 T. METHODS: Scans were performed on the brain of four healthy volunteers at 0.55 and 3 T, using a 3D mGRE sequence. The myelin water fraction (MWF) was calculated for both field strengths using a nonnegative least squares (NNLS) algorithm, implemented in the qMRLab suite. The quality of these maps as well as single-voxel fits were compared visually for 0...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38009996/cest-and-nuclear-overhauser-enhancement-imaging-with%C3%A2-deep-learning-extrapolated-semisolid-magnetization-transfer-reference-scan-rescan-reproducibility-and%C3%A2-reliability-studies
#9
JOURNAL ARTICLE
Hye-Young Heo, Munendra Singh, Vivek Yedavalli, Shanshan Jiang, Jinyuan Zhou
PURPOSE: To develop a novel MR physics-driven, deep-learning, extrapolated semisolid magnetization transfer reference (DeepEMR) framework to provide fast, reliable magnetization transfer contrast (MTC) and CEST signal estimations, and to determine the reproducibility and reliability of the estimates from the DeepEMR. METHODS: A neural network was designed to predict a direct water saturation and MTC-dominated signal at a certain CEST frequency offset using a few high-frequency offset features in the Z-spectrum...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38009992/adjustment-of-rotation-and-saturation-effects-arose-for-cest-imaging
#10
JOURNAL ARTICLE
Tao Jin, Julius Juhyun Chung
PURPOSE: Endogenous CEST signal usually has low specificity due to contaminations from the magnetization transfer contrast (MTC) and other labile protons with overlapping or close Larmor frequencies. We propose to improve CEST signal specificity with adjustment of rotation and saturation effects (AROSE). METHODS: The AROSE approach measures the difference between CEST signals acquired with the same average irradiation power but largely different duty cycles, for example, a continuous wave or a high duty cycle pulse train versus a low duty cycle pulse train with a flip angle φ...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38009988/in-vivo-characterization-of-glycogen-storage-disease-type-iii-in-a-mouse-model-using-glyconoe-mri
#11
JOURNAL ARTICLE
Qing Zeng, Michael Machado, Chongxue Bie, Peter C M van Zijl, Sofi Malvar, Yuguo Li, Valentina D'souza, Kirsten Achilles Poon, Andrew Grimm, Nirbhay N Yadav
PURPOSE: Glycogen storage disease type III (GSD III) is a rare inherited metabolic disease characterized by excessive accumulation of glycogen in liver, skeletal muscle, and heart. Currently, there are no widely available noninvasive methods to assess tissue glycogen levels and disease load. Here, we use glycogen nuclear Overhauser effect (glycoNOE) MRI to quantify hepatic glycogen levels in a mouse model of GSD III. METHODS: Agl knockout mice (n = 13) and wild-type controls (n = 10) were scanned for liver glycogen content using glycoNOE MRI...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/38009927/evaluation-of-coaxial-dipole-antennas-as-transceiver-elements-of-human-head-array-for-ultra-high-field-mri-at-9-4t
#12
JOURNAL ARTICLE
G A Solomakha, D Bosch, F Glang, K Scheffler, N I Avdievich
PURPOSE: The aim of this work is to evaluate a new eight-channel transceiver (TxRx) coaxial dipole array for imaging of the human head at 9.4T developed to improve specific absorption rate (SAR) performance, and provide for a more compact and robust alternative to the state-of-the art dipole arrays. METHODS: First, the geometry of a single coaxial element was optimized to minimize peak SAR and sensitivity to the load variation. Next, a multi-tissue voxel model was used to numerically simulate a TxRx array coil that consisted of eight coaxial dipoles with the optimal configuration...
November 27, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37997011/changes-in-tissue-sodium-concentration-and-sodium-relaxation-times-during-the-maturation-of-human-knee-cartilage-ex-vivo-23-na-mri-study-at-10-5%C3%A2-t
#13
JOURNAL ARTICLE
Štefan Zbýň, Kai D Ludwig, Lauren E Watkins, Russell L Lagore, Amanda Nowacki, Ferenc Tóth, Marc A Tompkins, Lin Zhang, Gregor Adriany, Garry E Gold, Kevin G Shea, Armin M Nagel, Cathy S Carlson, Gregory J Metzger, Jutta M Ellermann
PURPOSE: To evaluate the influence of skeletal maturation on sodium (23 Na) MRI relaxation parameters and the accuracy of tissue sodium concentration (TSC) quantification in human knee cartilage. METHODS: Twelve pediatric knee specimens were imaged with whole-body 10.5 T MRI using a density-adapted 3D radial projection sequence to evaluate 23 Na parameters: B1 + , T1 , biexponential <mml:math xmlns:mml="https://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msubsup><mml:mi>T</mml:mi> <mml:mn>2</mml:mn> <mml:mo>*</mml:mo></mml:msubsup> </mml:mrow> <mml:annotation>$$ {\mathrm{T}}_2^{\ast } $$</mml:annotation></mml:semantics> </mml:math> , and TSC...
November 23, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37994235/minimization-of-eddy-current-artifacts-in-sequences-with-periodic-dynamics
#14
JOURNAL ARTICLE
Sebastian Flassbeck, Jakob Assländer
PURPOSE: To minimize eddy current artifacts in periodic pulse sequences with balanced gradient moments as, for example, used for quantitative MRI. THEORY AND METHODS: Eddy current artifacts in balanced sequences result from large jumps in k-space. In quantitative MRI, one often samples some spin dynamics repeatedly while acquiring different parts of k-space. We swap individual k-space lines between different repetitions in order to minimize jumps in temporal succession without changing the overall trajectory...
November 22, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37986237/efficiently-building-receive-arrays-with-electromagnetic-simulations-and-additive-manufacturing-a-two-layer-32-channel-prototype-for-7t-brain-mri
#15
JOURNAL ARTICLE
Paul-François Gapais, Michel Luong, François Nizery, Gabriel Maitre, Eric Giacomini, Jules Guillot, Alexandre Vignaud, Djamel Berrahou, Marc Dubois, Redha Abdeddaim, Elodie Georget, Sajad Hosseinnezhadian, Alexis Amadon
PURPOSE: We propose a comprehensive workflow to design and build fully customized dense receive arrays for MRI, providing prediction of SNR and g-factor. Combined with additive manufacturing, this method allows an efficient implementation for any arbitrary loop configuration. To demonstrate the methodology, an innovative two-layer, 32-channel receive array is proposed. METHODS: The design workflow is based on numerical simulations using a commercial 3D electromagnetic software associated with circuit model co-simulations to provide the most accurate results in an efficient time...
November 20, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37984456/independent-component-analysis-ica-applied-to-dynamic-oxygen-enhanced-mri-oe-mri-for-robust-functional-lung-imaging-at-3%C3%A2-t
#16
JOURNAL ARTICLE
Sarah H Needleman, Mina Kim, Jamie R McClelland, Josephine H Naish, Marta Tibiletti, James P B O'Connor, Geoff J M Parker
PURPOSE: Dynamic lung oxygen-enhanced MRI (OE-MRI) is challenging due to the presence of confounding signals and poor signal-to-noise ratio, particularly at 3 T. We have created a robust pipeline utilizing independent component analysis (ICA) to automatically extract the oxygen-induced signal change from confounding factors to improve the accuracy and sensitivity of lung OE-MRI. METHODS: Dynamic OE-MRI was performed on healthy participants using a dual-echo multi-slice spoiled gradient echo sequence at 3 T and cyclical gas delivery...
November 20, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37984415/ethical-considerations-of-preclinical-models-in-imaging-research
#17
LETTER
Eduardo A Garza-Villarreal, Linda Moy, Hui Mao, Tarique Hussain, Janine M Lupo, Candace C Fleischer, Andrew D Scott
No abstract text is available yet for this article.
November 20, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37957820/diffusional-kurtosis-time-dependence-and-the-water-exchange-rate-for-the-multi-compartment-k%C3%A3-rger-model
#18
JOURNAL ARTICLE
Jens H Jensen
PURPOSE: To demonstrate an analytic formula giving the time dependence of the diffusional kurtosis for the Kärger model (KM) with an arbitrary number of exchanging compartments and its application in estimating the mean KM water exchange rate. THEORY AND METHODS: The general formula for the kurtosis is derived from a power series solution for the multi-compartment KM. A lower bound on the exchange rate is established from the observation that the kurtosis is always a logarithmically convex function of time...
November 13, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37946584/diffusion-weighted-mr-spectroscopy-consensus-recommendations-and-resources-from-acquisition-to-modeling
#19
JOURNAL ARTICLE
Clémence Ligneul, Chloé Najac, André Döring, Christian Beaulieu, Francesca Branzoli, William T Clarke, Cristina Cudalbu, Guglielmo Genovese, Saad Jbabdi, Ileana Jelescu, Dimitrios Karampinos, Roland Kreis, Henrik Lundell, Małgorzata Marjańska, Harald E Möller, Jessie Mosso, Eloïse Mougel, Stefan Posse, Stefan Ruschke, Kadir Simsek, Filip Szczepankiewicz, Assaf Tal, Chantal Tax, Georg Oeltzschner, Marco Palombo, Itamar Ronen, Julien Valette
Brain cell structure and function reflect neurodevelopment, plasticity, and aging; and changes can help flag pathological processes such as neurodegeneration and neuroinflammation. Accurate and quantitative methods to noninvasively disentangle cellular structural features are needed and are a substantial focus of brain research. Diffusion-weighted MRS (dMRS) gives access to diffusion properties of endogenous intracellular brain metabolites that are preferentially located inside specific brain cell populations...
November 9, 2023: Magnetic Resonance in Medicine
https://read.qxmd.com/read/37946544/quantitative-diffusion-imaging-and-genotype-by-sex-interactions-in-a-rat-model-of-alexander-disease
#20
JOURNAL ARTICLE
Nicholas A Stowe, Ajay P Singh, Brian R Barnett, Sue Y Yi, Paloma C Frautschi, Albee Messing, Tracy L Hagemann, John-Paul J Yu
PURPOSE: The clinical diagnosis and classification of Alexander disease (AxD) relies in part on qualitative neuroimaging biomarkers; however, these biomarkers fail to distinguish and discriminate different subtypes of AxD, especially in the presence of overlap in clinical symptoms. To address this gap in knowledge, we applied neurite orientation dispersion and density imaging (NODDI) to an innovative CRISPR-Cas9 rat genetic model of AxD to gain quantitative insights into the neural substrates and brain microstructural changes seen in AxD and to potentially identify novel quantitative NODDI biomarkers of AxD...
November 9, 2023: Magnetic Resonance in Medicine
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