Journal of magnetic resonance最新文献_第2页

Simultaneous multinuclear MRI via a single RF channel 通过单个射频通道同时进行多核磁共振成像

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-10-09 DOI: 10.1016/j.jmr.2024.107782

{"title":"Simultaneous multinuclear MRI via a single RF channel","authors":"","doi":"10.1016/j.jmr.2024.107782","DOIUrl":"10.1016/j.jmr.2024.107782","url":null,"abstract":"<div><div>Magnetic resonance imaging (MRI) stands as one of the most powerful noninvasive and non-destructive imaging techniques, finding extensive utility in medical and industrial applications. Its ability to acquire signals from multiple nuclei grants it additional levels of strength by providing multi-dimensional datasets of the object under test. However, this typically requires dedicated hardware to detect each nucleus. In this paper, we report on the use of a digital lock-in amplifier to perform simultaneous multi-nuclear MRI with a single physical radio frequency (RF) channel. While we showcase this concept by demonstrating the results of fully parallel (TX and RX) <sup>1</sup>H and <sup>19</sup>F MRI images, we emphasize that it is not limited to two nuclei but can accommodate more nuclei with no extra cost on the hardware or scan time. The scalability is virtually unlimited, constrained only by the processing speed of the digital unit. Furthermore, we demonstrate that the quality of parallel imaging with SNR of 54 is comparable to the commercial single channel with SNR of 43. Thus with no reduction in imaging quality, the proposed concept promises a tremendous reduction in scan time, system complexity, and hardware costs.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Optimization of 15N–13C double-resonance NMR experiments under low temperature magic angle spinning dynamic nuclear polarization conditions 低温魔角旋转动态核极化条件下 15N-13C 双共振核磁共振实验的优化。

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-10-02 DOI: 10.1016/j.jmr.2024.107783

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In Memoriam: Professor Vladimír Sklenář (April 16, 1951 – April 13, 2024) 悼念弗拉迪米尔-斯克雷纳日教授（1951 年 4 月 16 日 - 2024 年 4 月 13 日）。

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-10-02 DOI: 10.1016/j.jmr.2024.107784

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Peculiarities in Rabi oscillations for fast-relaxing electron spins 快速松弛电子自旋拉比振荡的特殊性

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-09-26 DOI: 10.1016/j.jmr.2024.107781

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The matrix pencil as a tunable filter 作为可调滤波器的矩阵铅笔

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-09-23 DOI: 10.1016/j.jmr.2024.107780

{"title":"The matrix pencil as a tunable filter","authors":"","doi":"10.1016/j.jmr.2024.107780","DOIUrl":"10.1016/j.jmr.2024.107780","url":null,"abstract":"<div><div>Despite inherent sensitivity constraints, nuclear magnetic resonance (NMR) plays an indispensable role in probing molecular structures and dynamics across scientific disciplines. Remarkably, while extensive efforts have targeted instrumental and experimental sensitivity improvements, comparatively little focus has been dedicated to sensitivity enhancement through signal analysis. Amidst this present gap, the matrix pencil method (MPM) has emerged as a versatile algorithm that offers tunable filtering and phasing capabilities. Extensive prior research has established the MPM as an adept fitting tool in signal analysis. Here, the efficacy of the MPM is investigated by precisely modeling noisy data to separate information-bearing signals from noise, thereby expanding its utility in various magnetic resonance applications. Simulated data is used to confirm the ability of the MPM to discern and separate signals from noise. Comparative analyses against standard Fourier-based filtering methods highlight the superior performance of the matrix pencil filter (MPF) in preserving signal fidelity without introducing aliasing artifacts. A variety of experimental data is then explored to demonstrate the proficiency of the MPF in characterizing signal components and correcting phase distortions. Collectively, these case studies underscore the filtering capacity of the MPM, portending its use for analytical sensitivity improvements in a wide range of NMR applications.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Operando electron spin probes for the study of battery processes 用于研究电池过程的操作性电子自旋探针

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-09-14 DOI: 10.1016/j.jmr.2024.107772

{"title":"Operando electron spin probes for the study of battery processes","authors":"","doi":"10.1016/j.jmr.2024.107772","DOIUrl":"10.1016/j.jmr.2024.107772","url":null,"abstract":"<div><p><em>Operando</em> electron spin probes, namely magnetometry and electron paramagnetic resonance (EPR), provide real-time insights into the electrochemical processes occurring in battery materials and devices. In this work, we describe the design criteria and outline the development of <em>operando</em> magnetometry and EPR electrochemical cells. Notably, we show that a clamping mechanism, or springs, are needed to achieve sufficient compression of the battery stack and an electrochemical performance on par with that of a standard Swagelok-type cell. The tandem use of <em>operando</em> EPR and magnetometry allows us to identify five distinct and reversible redox processes taking place on charge and discharge of the intercalation-type LiNi<sub>0.5</sub>Mn<sub>0.5</sub>O<sub>2</sub> Li-ion cathode. While redox processes in conversion-type electrodes are notoriously difficult to investigate using standard characterization methods (e.g. X-ray based) and/or <em>post mortem</em> analysis, due to the formation of poorly crystalline and metastable reaction intermediates and products during cycling, we show that <em>operando</em> magnetometry provides unique insight into the kinetics and reversibility of Fe nanoparticle formation in the Na<sub>3</sub>FeF<sub>6</sub> electrode for Na-based batteries. Step increases in the cell magnetization upon extended cycling indicate the build-up of Fe nanoparticles in the system, hinting at only partially reversible charge–discharge processes. The broad applicability of the tools developed herein to a range of electrode chemistries and structures, from intercalation to conversion electrodes, and from crystalline to amorphous systems, makes them particularly promising for the development of electrochemical energy storage technologies and beyond.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724001563/pdfft?md5=9fe9fcb759db21e365298307ee6aa606&pid=1-s2.0-S1090780724001563-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recurrent neural network-aided processing of incomplete free induction decays in 1H-MRS of the brain 大脑 1H-MRS 中不完全自由感应衰减的递归神经网络辅助处理方法

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-09-12 DOI: 10.1016/j.jmr.2024.107762

{"title":"Recurrent neural network-aided processing of incomplete free induction decays in 1H-MRS of the brain","authors":"","doi":"10.1016/j.jmr.2024.107762","DOIUrl":"10.1016/j.jmr.2024.107762","url":null,"abstract":"<div><p>In the case of limited sampling windows or truncation of free induction decays (FIDs) for artifact removal in proton magnetic resonance spectroscopy (<sup>1</sup>H‐MRS) and spectroscopic imaging (<sup>1</sup>H‐MRSI), metabolite quantification needs to be performed on incomplete FIDs. Given that FIDs are naturally time-domain sequential data, we investigated the potential of recurrent neural network (RNN)-types of neural networks (NNs) in the processing of incomplete human brain FIDs with or without FID restoration prior to quantitative analysis at 3.0T.</p><p>First, we employed an RNN encoder-decoder and developed it to restore incomplete FIDs (rRNN) with different amounts of sampled data. The quantification of metabolites from the rRNN-restored FIDs was achieved by using LCModel. Second, we modified the RNN encoder-decoder and developed it to convert incomplete brain FIDs into incomplete metabolite-only FIDs without restoration, followed by linear regression using a metabolite basis set for quantitative analysis (cRNN). In consideration of the practical benefit of the FID restoration with respect to pure zero-filling, development and analysis of the NNs were focused particularly on the incomplete FIDs with only the first 64 data points retained. All NNs were trained on simulated data and tested mainly on in vivo data acquired from healthy volunteers (n = 27).</p><p>Strong correlations were obtained between the NN-derived and ground truth metabolite content (LCModel-derived content on fully sampled FIDs) for myo‐inositol, total choline, and total creatine (normalized to total N-acetylaspartate) on the in vivo data using both rRNN (R = 0.83–0.94; p ≤ 0.05) and cRNN (R = 0.86–0.91; p ≤ 0.05).</p><p>RNN-types of NNs have potential in the quantification of the major brain metabolites from the FIDs with substantially reduced sampled data points. For the metabolites with low to medium SNR, the performance of the NNs needs to be further improved, for which development of more elaborate and advanced simulation techniques would be of help, but remains challenging.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142238091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A comparison of pulse and CW EPR T2-relaxation measurements of an inhomogeneously broadened nitroxide spin probe undergoing Heisenberg spin exchange 2. The intercept discrepancy 对进行海森堡自旋交换的不均匀拓宽亚硝基自旋探针进行的脉冲和连续波 EPR T2- 弛豫测量的比较 2.截距差异

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-09-12 DOI: 10.1016/j.jmr.2024.107771

{"title":"A comparison of pulse and CW EPR T2-relaxation measurements of an inhomogeneously broadened nitroxide spin probe undergoing Heisenberg spin exchange 2. The intercept discrepancy","authors":"","doi":"10.1016/j.jmr.2024.107771","DOIUrl":"10.1016/j.jmr.2024.107771","url":null,"abstract":"<div><div>Experimental confirmation of a theoretical prediction of a non-linear broadening of the spin packets of nitroxide free radicals due to Heisenberg spin exchange at low concentrations, <span><math><mrow><mi>C</mi></mrow></math></span>, is presented. A recent demonstration that spectra with resolved proton hyperfine structure may be analyzed efficiently and accurately was utilized to confirm the theory. As <span><math><mrow><mi>C</mi><mo>→</mo><mn>0</mn></mrow></math></span>, a plot of the spin-packet line width (SPW) curves downward due to the presence of proton hyperfine couplings that increase the number of distinguishable quantum spin states. At higher <span><math><mrow><mi>C</mi></mrow></math></span>, the broadening is linear with <span><math><mrow><mi>C</mi></mrow></math></span> and the results for the spin exchange rate constant determined from the slope of the broadening of the average spin-packet line width and electron spin echo measurements are in agreement. It is shown that applying modest digital smoothing does not change the values of the SPW. An example of a practical application of these methods to published work is presented, allowing an enigma to be resolved.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Restriction-induced time-dependent transcytolemmal water exchange: Revisiting the Kӓrger exchange model 限制诱导的时间依赖性跨细胞膜水交换：重新审视Kӓrger交换模型

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-08-30 DOI: 10.1016/j.jmr.2024.107760

{"title":"Restriction-induced time-dependent transcytolemmal water exchange: Revisiting the Kӓrger exchange model","authors":"","doi":"10.1016/j.jmr.2024.107760","DOIUrl":"10.1016/j.jmr.2024.107760","url":null,"abstract":"<div><p>The Kӓrger model and its derivatives have been widely used to incorporate transcytolemmal water exchange rate, an essential characteristic of living cells, into analyses of diffusion MRI (dMRI) signals from tissues. The Kӓrger model consists of two homogeneous exchanging components coupled by an exchange rate constant and assumes measurements are made with sufficiently long diffusion time and slow water exchange. Despite successful applications, it remains unclear whether these assumptions are generally valid for practical dMRI sequences and biological tissues. In particular, barrier-induced restrictions to diffusion produce inhomogeneous magnetization distributions in relatively large-sized compartments such as cancer cells, violating the above assumptions. The effects of this inhomogeneity are usually overlooked. We performed computer simulations to quantify how restriction effects, which in images produce edge enhancements at compartment boundaries, influence different variants of the Kӓrger-model. The results show that the edge enhancement effect will produce larger, time-dependent estimates of exchange rates in e.g., tumors with relatively large cell sizes (>10 μm), resulting in overestimations of water exchange as previously reported. Moreover, stronger diffusion gradients, longer diffusion gradient durations, and larger cell sizes, all cause more pronounced edge enhancement effects. This helps us to better understand the feasibility of the Kärger model in estimating water exchange in different tissue types and provides useful guidance on signal acquisition methods that may mitigate the edge enhancement effect. This work also indicates the need to correct the overestimated transcytolemmal water exchange rates obtained assuming the Kärger-model.</p></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1090780724001447/pdfft?md5=f8473d8afcad5e5d4a4d7cea3da4a920&pid=1-s2.0-S1090780724001447-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142147208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The NOAH HSQC-COSY module revisited: A theoretical and practical comparison of pulse sequences 重新审视 NOAH HSQC-COSY 模块：脉冲序列的理论与实践比较

IF 2 3区化学

Journal of magnetic resonance Pub Date : 2024-08-24 DOI: 10.1016/j.jmr.2024.107759

引用次数: 0