Journal of magnetic resonance最新文献_第4页

Separate and detailed characterization of signal and noise at low resonance frequencies 分离和详细表征信号和噪声在低共振频率

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-09-22 DOI: 10.1016/j.jmr.2025.107956

A. Guinness , Alec A. Beaton , John M. Franck

When developing or deploying a Nuclear Magnetic Resonance (NMR) spectrometer, especially for Overhauser Dynamic Nuclear Polarization (ODNP) or other experiments that require low-volume low-field measurements, the ability to mitigate noise and to quantitatively predict signal amplitude prove crucial. A quantitative treatment allows separate analysis of signal and noise and independent optimization of each. In particular, the results here emphasize that clarity and insight come from (1) characterizing the spectral distribution of the noise, and (2) integrating elements of theory and notation originally developed for Electron Spin Resonance (ESR) spectroscopy. Specifically, the spectral noise density “fingerprint spectrum” identifies sources of electromagnetic interference (EMI) and definitively confirms which actions do and do not mitigate the EMI, while the quantitative ratio (

Λ

) of

B_{1}

to the square root of the power on the transmission line provides a useful focal point that simplifies the prediction of signal intensity and that decomposes into a few simple but exact factors. Thus, this article provides a relatively comprehensive overview of signal and noise in low-field NMR instruments. The protocol/toolkit introduced here should apply to a wide range of instruments, and give most spectroscopists the freedom to systematically design sensitive NMR hardware even in cases where it must be integrated with multiple other hardware modules (e.g., an existing ESR system), or where other requirements constrain the design of the NMR hardware. It enables a systematic approach to instrument design and optimization. For the specific X-band ODNP design demonstrated here (and utilized in other laboratories), it facilitates a reduction of the noise power by more than an order of magnitude, and accurately predicts the signal amplitude from measurements of the nutation frequency. Finally, it introduces reasoning to exactly determine the field distribution factor (

η^{'}

, essentially, a more specific definition of the filling factor) experimentally from

Λ

and thus identifies the inefficient distribution of fields in the hairpin loop probe as the main remaining bottleneck for the improvement of low-field, low-volume ODNP signal-to-noise ratio (SNR).

在开发或部署核磁共振（NMR）光谱仪时，特别是对于需要小体积低场测量的Overhauser动态核极化（ODNP）或其他实验，减轻噪声和定量预测信号幅度的能力至关重要。定量处理允许信号和噪声的独立分析和各自的独立优化。特别是，这里的结果强调了清晰度和洞察力来自(1)表征噪声的光谱分布，以及(2)整合最初为电子自旋共振（ESR）光谱开发的理论和符号元素。具体来说，频谱噪声密度“指纹频谱”识别电磁干扰（EMI）的来源，并明确确认哪些行为会减轻EMI，哪些不会减轻EMI，而B1与传传线上功率的平方根的定量比（Λ）提供了一个有用的焦点，简化了信号强度的预测，并分解为几个简单但精确的因素。因此，本文对低场核磁共振仪器中的信号和噪声进行了较为全面的概述。这里介绍的协议/工具包应该适用于广泛的仪器，并给予大多数光谱学家系统地设计敏感核磁共振硬件的自由，即使在它必须与多个其他硬件模块集成的情况下（例如，现有的ESR系统），或者在其他要求限制核磁共振硬件设计的情况下。它使仪器设计和优化的系统方法。对于这里演示的特定x波段ODNP设计（并在其他实验室中使用），它有助于将噪声功率降低一个数量级以上，并从章动频率的测量中准确预测信号幅度。最后，引入推理，从Λ实验中精确确定场分布因子（η′，本质上是填充因子的更具体定义），从而确定发卡环探针中场的低效分布是提高低场，小体积ODNP信噪比（SNR）的主要瓶颈。

{"title":"Separate and detailed characterization of signal and noise at low resonance frequencies","authors":"A. Guinness , Alec A. Beaton , John M. Franck","doi":"10.1016/j.jmr.2025.107956","DOIUrl":"10.1016/j.jmr.2025.107956","url":null,"abstract":"<div><div>When developing or deploying a Nuclear Magnetic Resonance (NMR) spectrometer, especially for Overhauser Dynamic Nuclear Polarization (ODNP) or other experiments that require low-volume low-field measurements, the ability to mitigate noise and to quantitatively predict signal amplitude prove crucial. A quantitative treatment allows separate analysis of signal and noise and independent optimization of each. In particular, the results here emphasize that clarity and insight come from (1) characterizing the spectral distribution of the noise, and (2) integrating elements of theory and notation originally developed for Electron Spin Resonance (ESR) spectroscopy. Specifically, the spectral noise density “fingerprint spectrum” identifies sources of electromagnetic interference (EMI) and definitively confirms which actions do and do not mitigate the EMI, while the quantitative ratio (<span><math><mi>Λ</mi></math></span>) of <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> to the square root of the power on the transmission line provides a useful focal point that simplifies the prediction of signal intensity and that decomposes into a few simple but exact factors. Thus, this article provides a relatively comprehensive overview of signal and noise in low-field NMR instruments. The protocol/toolkit introduced here should apply to a wide range of instruments, and give most spectroscopists the freedom to systematically design sensitive NMR hardware even in cases where it must be integrated with multiple other hardware modules (<em>e.g.</em>, an existing ESR system), or where other requirements constrain the design of the NMR hardware. It enables a systematic approach to instrument design and optimization. For the specific X-band ODNP design demonstrated here (and utilized in other laboratories), it facilitates a reduction of the noise power by more than an order of magnitude, and accurately predicts the signal amplitude from measurements of the nutation frequency. Finally, it introduces reasoning to exactly determine the field distribution factor (<span><math><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span>, essentially, a more specific definition of the filling factor) experimentally from <span><math><mi>Λ</mi></math></span> and thus identifies the inefficient distribution of fields in the hairpin loop probe as the main remaining bottleneck for the improvement of low-field, low-volume ODNP signal-to-noise ratio (SNR).</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107956"},"PeriodicalIF":1.9,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145120051","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 simple algorithm to suppress diagonal peaks in high-resolution homonuclear chemical shift correlation NMR spectra 一种抑制高分辨率同核化学位移相关核磁共振谱对角峰的简单算法。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-09-13 DOI: 10.1016/j.jmr.2025.107967

Shengyu Zhang , Jhinuk Saha , Yuchen Li , Xinhua Peng , Ryan P. McGlinchey , Ayyalusamy Ramamoorthy , Riqiang Fu

Previous experimental strategies aimed at completely suppressing diagonal peaks in NMR homonuclear correlation spectra often resulted in reduced sensitivity for cross peaks. In this work, we report a spectral shearing approach that transforms diagonal peaks along the diagonal axis of a homonuclear correlation spectrum into a zero-frequency line in the indirect dimension. This allows for effective extraction and substantial suppression of diagonal peaks using a recently proposed data processing algorithm based on quadrature-detected spin-echo diagonal peak suppression. Since the shearing process only rearranges the positions of cross peaks without affecting their intensities, the sensitivity of cross peaks is fully preserved while diagonal peaks are significantly reduced. The effectiveness of this method is demonstrated using uniformly ¹³C,¹⁵N labeled α-synuclein amyloid fibrils and aquaporin Z membrane protein samples.

以往旨在完全抑制核磁共振同核相关谱对角峰的实验策略往往导致交叉峰灵敏度降低。在这项工作中，我们报告了一种光谱剪切方法，该方法将沿同核相关谱对角线轴的对角峰转换为间接维的零频率线。使用最近提出的基于正交检测自旋回波对角峰抑制的数据处理算法，这允许有效地提取和大量抑制对角峰。由于剪切过程只是重新排列了交叉峰的位置，而不影响其强度，因此交叉峰的灵敏度得到了充分的保留，而对角峰的灵敏度明显降低。用13C、15N标记的α-突触核蛋白淀粉样原纤维和水通道蛋白Z膜蛋白样品证明了该方法的有效性。

引用次数: 0

Residual motion artifact removal enables dynamic μMRI of a behaving Pachnoda marginata 残馀运动伪影的去除，使动态μMRI的行为Pachnoda边缘

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-09-04 DOI: 10.1016/j.jmr.2025.107954

Ajmal Chenakkara , Mazin Jouda , Ulrike Wallrabe , Jan G. Korvink

Microscopic magnetic resonance imaging, also referred to as

μ

MRI, is a non-invasive imaging modality ideal for studying small live model organisms. However,

μ

MRI raw data acquisition is inherently sequential and slow in comparison to the biomechanics timescale of the behaving organism, leading to motion artifacts upon image reconstruction. Recently, we have developed an integrated spherical treadmill with a prospectively triggered k-space acquisition technique to provide position consistency for studying live, behaving insect using

μ

MRI. Despite this advancement, behaving insects on the treadmill still exhibited motion artifacts due to tethered locomotion being coupled with internal organ dynamics. Here, we are addressing the large-scale non-rigid nature of the abdominal motion of the behaving insect by developing a fully retrospective gating strategy using the motion information obtained from an in-situ computer vision system. Residual motion artifacts persisting after gating are effectively managed through a deep learning technique. We trained a U-Net-based deep convolutional neural network using pairs of simulated motion-corrupted and motion-free images as a supervised image-to-image translation problem. Our results demonstrate that combining retrospective gated

μ

MRI reconstruction with a deep learning residual motion compensation technique can significantly reduce the motional artifacts, thereby paving the way for the non-invasive dynamic imaging studies of behaving organisms with 117

μ

m in-plane resolution.

显微磁共振成像，也被称为μMRI，是一种非侵入性的成像方式，非常适合研究小型活模式生物。然而，与行为生物体的生物力学时间尺度相比，μMRI原始数据采集固有的顺序和缓慢，导致图像重建时的运动伪影。最近，我们开发了一种集成的球形跑步机，该跑步机具有前瞻性触发k空间采集技术，为使用μMRI研究活昆虫提供位置一致性。尽管有了这一进展，但在跑步机上活动的昆虫仍然表现出运动伪影，因为系绳运动与内部器官动力学相结合。在这里，我们通过使用从原位计算机视觉系统获得的运动信息开发一个完全回顾性的门控策略，来解决行为昆虫腹部运动的大规模非刚性性质。通过深度学习技术有效地处理门控后持续存在的残余运动伪影。我们训练了一个基于u - net的深度卷积神经网络，使用对模拟的运动损坏和无运动的图像作为监督图像到图像的翻译问题。我们的研究结果表明，将回溯门控μMRI重建与深度学习残余运动补偿技术相结合可以显著减少运动伪影，从而为117 μm平面内分辨率的行为生物的无创动态成像研究铺平了道路。

{"title":"Residual motion artifact removal enables dynamic μMRI of a behaving Pachnoda marginata","authors":"Ajmal Chenakkara , Mazin Jouda , Ulrike Wallrabe , Jan G. Korvink","doi":"10.1016/j.jmr.2025.107954","DOIUrl":"10.1016/j.jmr.2025.107954","url":null,"abstract":"<div><div>Microscopic magnetic resonance imaging, also referred to as <span><math><mi>μ</mi></math></span>MRI, is a non-invasive imaging modality ideal for studying small live model organisms. However, <span><math><mi>μ</mi></math></span>MRI raw data acquisition is inherently sequential and slow in comparison to the biomechanics timescale of the behaving organism, leading to motion artifacts upon image reconstruction. Recently, we have developed an integrated spherical treadmill with a prospectively triggered k-space acquisition technique to provide position consistency for studying live, behaving insect using <span><math><mi>μ</mi></math></span>MRI. Despite this advancement, behaving insects on the treadmill still exhibited motion artifacts due to tethered locomotion being coupled with internal organ dynamics. Here, we are addressing the large-scale non-rigid nature of the abdominal motion of the behaving insect by developing a fully retrospective gating strategy using the motion information obtained from an in-situ computer vision system. Residual motion artifacts persisting after gating are effectively managed through a deep learning technique. We trained a U-Net-based deep convolutional neural network using pairs of simulated motion-corrupted and motion-free images as a supervised image-to-image translation problem. Our results demonstrate that combining retrospective gated <span><math><mi>μ</mi></math></span>MRI reconstruction with a deep learning residual motion compensation technique can significantly reduce the motional artifacts, thereby paving the way for the non-invasive dynamic imaging studies of behaving organisms with 117 <span><math><mi>μ</mi></math></span>m in-plane resolution.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107954"},"PeriodicalIF":1.9,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048178","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

Significant acceleration of solid-state NMR simulations via three-angle powder averaging 通过三角度粉末平均显著加速固态核磁共振模拟

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-30 DOI: 10.1016/j.jmr.2025.107966

Elijah Burlinson , Frédéric A. Perras

The anisotropic frequency shifts imparted onto the NMR resonance frequency depend on the spherical angular coordinates that describe the orientations of the NMR interaction tensors with respect to the applied magnetic field direction. Experiments performed using magic-angle spinning, however, gain a dependence on a third angle: the rotor phase γ. Traditionally, a carousel average is performed to integrate over γ, which leads to a slow convergence of intensities without contributing to the underlying powder patterns. Herein, we show an order of magnitude acceleration in computation time may be obtained by including the γ-averaging into the main powder average to eliminate redundant calculation of resonance frequencies.

传递到核磁共振共振频率上的各向异性频移取决于描述核磁共振相互作用张量相对于外加磁场方向的方向的球角坐标。然而，使用魔角旋转进行的实验获得了对第三个角度的依赖：转子相位γ。传统上，对γ进行旋转平均积分，导致强度缓慢收敛，而不会影响潜在的粉末图案。通过在主粉末平均中加入γ-平均来消除共振频率的冗余计算，可以在计算时间上得到一个数量级的加速。

引用次数: 0

Revealing the sensitivity of methyl tunneling towards local environment changes with quantum-rotor EPR spectroscopy 利用量子转子EPR光谱揭示甲基隧穿对局部环境变化的敏感性

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-26 DOI: 10.1016/j.jmr.2025.107943

Andrea Eggeling, Janne Soetbeer, Gunnar Jeschke

Methyl rotors have potential as local environment probes because their rotation barrier is sensitive to hindering interactions with the nearby surrounding. Quantum-rotor electron paramagnetic resonance (EPR) measurements allow access to this local environment information of the methyl rotor if it is coupled to an electron spin. This is the case for commonly used nitroxide-based spin-labels, where electron spin echo envelope modulation (ESEEM) signals exhibit two contributions on different time scales at low temperatures. The slower decaying contribution is related to matrix-driven nuclear pair ESEEM while the faster contribution originates from methyl tunneling of the electron spin-coupled methyl rotors. The tunneling ESEEM contribution contains local environment information in terms of a distribution of the rotation barrier, which can be quantified using the methyl quantum rotor model. Here, we study the sensitivity of the tunneling behavior towards changes in the rotors’ surrounding by systematically investigating the two-pulse ESEEM signal of nitroxide spin probes containing two pairs of geminal methyl groups in different biologically-relevant matrix compositions. We find that the nitroxide ring structure of these probes strongly impacts the rotation barrier of the observed methyl rotors whereas the matrix surrounding does not affect the underlying rotation barrier distribution. These insights are crucial for designing nitroxide-based spin-labels as local environments probes in combination with site-directed spin-labeling for protein structure elucidation.

甲基转子具有作为局部环境探针的潜力，因为它们的旋转势垒对阻碍与周围环境的相互作用很敏感。量子转子电子顺磁共振（EPR）测量允许访问这个甲基转子的局部环境信息，如果它是耦合到一个电子自旋。这是常用的基于氮氧化物的自旋标签的情况，其中电子自旋回波包络调制（ESEEM）信号在低温下的不同时间尺度上表现出两种贡献。较慢的衰减贡献与基质驱动的核对ESEEM有关，而较快的衰减贡献来自电子自旋耦合甲基转子的甲基隧穿。隧道效应的ESEEM贡献包含了旋转势垒分布的局部环境信息，这些信息可以使用甲基量子转子模型进行量化。在这里，我们通过系统地研究含有两对双甲基的氮氧化物自旋探针在不同生物相关基质组成中的双脉冲ESEEM信号，来研究隧道行为对转子周围变化的敏感性。我们发现这些探针的氮氧化物环结构强烈影响观察到的甲基转子的旋转势垒，而周围的基质不影响底层的旋转势垒分布。这些见解对于设计基于氮氧化物的自旋标记作为局部环境探针与位点定向自旋标记相结合用于蛋白质结构阐明至关重要。

{"title":"Revealing the sensitivity of methyl tunneling towards local environment changes with quantum-rotor EPR spectroscopy","authors":"Andrea Eggeling, Janne Soetbeer, Gunnar Jeschke","doi":"10.1016/j.jmr.2025.107943","DOIUrl":"10.1016/j.jmr.2025.107943","url":null,"abstract":"<div><div>Methyl rotors have potential as local environment probes because their rotation barrier is sensitive to hindering interactions with the nearby surrounding. Quantum-rotor electron paramagnetic resonance (EPR) measurements allow access to this local environment information of the methyl rotor if it is coupled to an electron spin. This is the case for commonly used nitroxide-based spin-labels, where electron spin echo envelope modulation (ESEEM) signals exhibit two contributions on different time scales at low temperatures. The slower decaying contribution is related to matrix-driven nuclear pair ESEEM while the faster contribution originates from methyl tunneling of the electron spin-coupled methyl rotors. The tunneling ESEEM contribution contains local environment information in terms of a distribution of the rotation barrier, which can be quantified using the methyl quantum rotor model. Here, we study the sensitivity of the tunneling behavior towards changes in the rotors’ surrounding by systematically investigating the two-pulse ESEEM signal of nitroxide spin probes containing two pairs of geminal methyl groups in different biologically-relevant matrix compositions. We find that the nitroxide ring structure of these probes strongly impacts the rotation barrier of the observed methyl rotors whereas the matrix surrounding does not affect the underlying rotation barrier distribution. These insights are crucial for designing nitroxide-based spin-labels as local environments probes in combination with site-directed spin-labeling for protein structure elucidation.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107943"},"PeriodicalIF":1.9,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908820","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

Flexible and shape-adjustable coaxial capacitor (COCA) coils for ultrahigh field MRI: a comparative analysis with rigid coils 用于超高场MRI的柔性和可调形状同轴电容器（COCA）线圈：与刚性线圈的比较分析

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-25 DOI: 10.1016/j.jmr.2025.107955

Ming Lu , Caiwan Sun , Xiaoyu Jiang , Jason E. Moore , John C. Gore , Xinqiang Yan

Flexible RF coils enhance patient comfort and increase filling factors, making them attractive for MRI. However, achieving first-mode resonance at 7 T for large-diameter, flexible coils remains a challenge. We present a coaxial capacitor (COCA) coil, which can be 10 cm in diameter and still operates in the first resonant mode at 298 MHz. Unlike coaxial cable coils that rely on self-resonance, the COCA coil combines ultrasoft Litz wire for inductance with a short coaxial structure for capacitance. Bench tests showed that a 1-capacitor COCA coil provides comparable tuning/matching robustness, effective detuning, and inter-element decoupling performance to conventional rigid coils with three distributed lumped capacitors. MRI acquisitions demonstrated high SNR, especially when the coil conformed to the curvature of the load, with up to 20 % SNR improvement over flat configurations. The coil's ability to retain tuning and matching across different shapes also supports the development of shape-adjustable arrays. By enabling flexible, large-diameter coils to operate in the first resonant mode at ultrahigh fields, the COCA design offers a promising solution for imaging anatomies with complex geometries, such as the shoulder, foot, and spine.

柔性射频线圈提高了患者的舒适度，增加了填充系数，使其对MRI具有吸引力。然而，在7 T下实现大直径柔性线圈的第一模共振仍然是一个挑战。我们提出了一种同轴电容器（COCA）线圈，它的直径可以是10厘米，仍然在298 MHz的第一谐振模式下工作。与依靠自共振的同轴电缆线圈不同，COCA线圈结合了超软利兹线的电感和短同轴结构的电容。台架测试表明，1电容器COCA线圈具有与具有3个分布式集总电容器的传统刚性线圈相当的调谐/匹配鲁棒性、有效失谐和元件间去耦性能。磁共振成像显示了高信噪比，特别是当线圈符合负载的曲率时，与平面配置相比，信噪比提高了20%。线圈在不同形状之间保持调谐和匹配的能力也支持了形状可调阵列的发展。通过使灵活的大直径线圈在超高场的第一共振模式下工作，COCA设计为具有复杂几何形状的解剖成像提供了一个有前途的解决方案，例如肩部，足部和脊柱。

{"title":"Flexible and shape-adjustable coaxial capacitor (COCA) coils for ultrahigh field MRI: a comparative analysis with rigid coils","authors":"Ming Lu , Caiwan Sun , Xiaoyu Jiang , Jason E. Moore , John C. Gore , Xinqiang Yan","doi":"10.1016/j.jmr.2025.107955","DOIUrl":"10.1016/j.jmr.2025.107955","url":null,"abstract":"<div><div>Flexible RF coils enhance patient comfort and increase filling factors, making them attractive for MRI. However, achieving first-mode resonance at 7 T for large-diameter, flexible coils remains a challenge. We present a coaxial capacitor (COCA) coil, which can be 10 cm in diameter and still operates in the first resonant mode at 298 MHz. Unlike coaxial cable coils that rely on self-resonance, the COCA coil combines ultrasoft Litz wire for inductance with a short coaxial structure for capacitance. Bench tests showed that a 1-capacitor COCA coil provides comparable tuning/matching robustness, effective detuning, and inter-element decoupling performance to conventional rigid coils with three distributed lumped capacitors. MRI acquisitions demonstrated high SNR, especially when the coil conformed to the curvature of the load, with up to 20 % SNR improvement over flat configurations. The coil's ability to retain tuning and matching across different shapes also supports the development of shape-adjustable arrays. By enabling flexible, large-diameter coils to operate in the first resonant mode at ultrahigh fields, the COCA design offers a promising solution for imaging anatomies with complex geometries, such as the shoulder, foot, and spine.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107955"},"PeriodicalIF":1.9,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912347","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

High-speed, high-memory NMR spectrometer and hyperpolarizer 高速，高存储核磁共振光谱仪和超偏振器

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-19 DOI: 10.1016/j.jmr.2025.107952

Leo Joon Il Moon , William Beatrez , Jason Ball , Joan Mercade , Mark Elo , Angad Singh , Emanuel Druga , Ashok Ajoy

We report on the development of a novel nuclear magnetic resonance (NMR) spectrometer, incorporating a high-speed, commercially available arbitrary waveform transceiver (AWT) – Tabor Proteus P9484M. The spectrometer is optimized for integrated electron-nuclear spin control and dynamic nuclear polarization (DNP) and leverages the AWT’s rapid sampling rate (9 Gs/s), significant memory capacity (16 GB), and efficient data transfer capabilities (6 Gs/s). These features enable effective NMR transmit–receive operations and electron control for DNP. In particular, the high sampling rates permit NMR pulse synthesis and signal reception directly at the Larmor frequency up to

\sim

2.7 GHz. This can yield NMR signal-to-noise ratio (SNR) improvements by obviating the need for signal heterodyning. Additionally, the spectrometer features on-board, phase-sensitive detection, enabled by numerically controlled oscillators (NCO); and windowed acquisition can be carried out over extended periods and across millions of pulses, enabling the interrogation of nuclear spin dynamics directly in the rotating frame. The device’s architecture opens up new avenues for NMR pulse control and DNP, including closed-loop feedback control, electron decoupling, 3D spin tracking, and potential applications in quantum sensing.

我们报告了一种新型核磁共振（NMR）波谱仪的发展，该波谱仪结合了高速，商用任意波形收发器(AWT) - Tabor Proteus P9484M。该光谱仪针对集成电子-核自旋控制和动态核极化（DNP）进行了优化，并利用了AWT的快速采样率（9 g /s）、显著的内存容量（16 GB）和高效的数据传输能力（6 g /s）。这些特点使有效的核磁共振发射-接收操作和电子控制DNP。特别是，高采样率允许在高达2.7 GHz的拉莫尔频率下直接进行核磁共振脉冲合成和信号接收。这可以通过消除信号外差来提高核磁共振信噪比（SNR）。此外，该光谱仪具有机载相敏检测功能，由数控振荡器（NCO）启用；窗口采集可以在较长的时间内进行，跨越数百万个脉冲，从而可以直接在旋转框架中询问核自旋动力学。该设备的架构为核磁共振脉冲控制和DNP开辟了新的途径，包括闭环反馈控制、电子解耦、3D自旋跟踪以及量子传感中的潜在应用。

{"title":"High-speed, high-memory NMR spectrometer and hyperpolarizer","authors":"Leo Joon Il Moon , William Beatrez , Jason Ball , Joan Mercade , Mark Elo , Angad Singh , Emanuel Druga , Ashok Ajoy","doi":"10.1016/j.jmr.2025.107952","DOIUrl":"10.1016/j.jmr.2025.107952","url":null,"abstract":"<div><div>We report on the development of a novel nuclear magnetic resonance (NMR) spectrometer, incorporating a high-speed, commercially available arbitrary waveform transceiver (AWT) – Tabor Proteus P9484M. The spectrometer is optimized for integrated electron-nuclear spin control and dynamic nuclear polarization (DNP) and leverages the AWT’s rapid sampling rate (9 Gs/s), significant memory capacity (16 GB), and efficient data transfer capabilities (6 Gs/s). These features enable effective NMR transmit–receive operations and electron control for DNP. In particular, the high sampling rates permit NMR pulse synthesis and signal reception directly at the Larmor frequency up to <span><math><mo>∼</mo></math></span>2.7 GHz. This can yield NMR signal-to-noise ratio (SNR) improvements by obviating the need for signal heterodyning. Additionally, the spectrometer features on-board, phase-sensitive detection, enabled by numerically controlled oscillators (NCO); and windowed acquisition can be carried out over extended periods and across millions of pulses, enabling the interrogation of nuclear spin dynamics directly in the rotating frame. The device’s architecture opens up new avenues for NMR pulse control and DNP, including closed-loop feedback control, electron decoupling, 3D spin tracking, and potential applications in quantum sensing.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107952"},"PeriodicalIF":1.9,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890855","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

Corrigendum to “The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose” [J. Magn. Reson. 284 (2017) 86–93] 心脏中葡萄糖产生乳酸的速率不受葡萄糖氘化的影响[J]。粉剂。理性，284(2017)86-93]。

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-18 DOI: 10.1016/j.jmr.2025.107942

Alexander M. Funk , Brian L. Anderson , Xiaodong Wen , Thomas Hever , Chalermchai Khemtong , Zoltan Kovacs , A. Dean Sherry , Craig R. Malloy

引用次数: 0

Recurrence formula-based automatic gradient eddy current compensation method for a 0.255 T MRI system 基于递推公式的0.255 T MRI自动梯度涡流补偿方法

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-18 DOI: 10.1016/j.jmr.2025.107951

Jinhao Liu , Miutian Wang , Wenchen Wang , Yaohui Wang , Wenhui Yang , Weimin Wang , Feng Liu

Gradient coils play a critical role in magnetic resonance imaging (MRI) systems by enabling spatial encoding through generating rapidly switching magnetic fields. However, these time-varying fields induce eddy currents in surrounding conductive structures, leading to gradient field distortions and imaging artifacts. In this study, we propose an automatic eddy current compensation method implemented on a field-programmable gate array (FPGA) platform. The approach employs iterative correction formulas for both linear gradient and

B_{0}

eddy fields, enabling real-time compensation. To enhance computational efficiency, a novel layout for the pre-emphasis (PE) unit is also introduced. Compared to conventional compensation techniques, the proposed FPGA-based solution offers significant improvements in implementation simplicity and system stability. Experimental results demonstrate that the residual direct- and cross-term eddy current fields are reduced to below 0.02%, equivalent to 4

μT / m

, for a test gradient of 20 mT/m. Furthermore, the

B_{0}

eddy field is suppressed to below 0.1

μT

when a

B_{0}

compensation coil is employed. These improvements effectively reduce ghosting artifacts in multi-slice gradient-echo (GRE) phantom images. The robustness of the method is further validated across various imaging sequences, including T1-weighted (T1w) and T2-weighted (T2w) protocols.

梯度线圈通过产生快速开关磁场实现空间编码，在磁共振成像（MRI）系统中起着至关重要的作用。然而，这些时变场会在周围的导电结构中产生涡流，导致梯度场畸变和成像伪影。在这项研究中，我们提出了一种在现场可编程门阵列（FPGA）平台上实现的自动涡流补偿方法。该方法采用线性梯度和B0涡旋场的迭代校正公式，实现实时补偿。为了提高计算效率，本文还介绍了一种新的预强调单元布局。与传统的补偿技术相比，所提出的基于fpga的补偿方案在实现简单性和系统稳定性方面有显著改进。实验结果表明，当测试梯度为20 mT/m时，直接项和交叉项涡流场的残余量降至0.02%以下，相当于4 μT/m。此外，采用B0补偿线圈将B0涡流场抑制到0.1 μT以下。这些改进有效地降低了多层梯度回波（GRE）伪影图像中的重影伪影。在各种成像序列中，包括t1加权（T1w）和t2加权（T2w）协议，进一步验证了该方法的鲁棒性。

{"title":"Recurrence formula-based automatic gradient eddy current compensation method for a 0.255 T MRI system","authors":"Jinhao Liu , Miutian Wang , Wenchen Wang , Yaohui Wang , Wenhui Yang , Weimin Wang , Feng Liu","doi":"10.1016/j.jmr.2025.107951","DOIUrl":"10.1016/j.jmr.2025.107951","url":null,"abstract":"<div><div>Gradient coils play a critical role in magnetic resonance imaging (MRI) systems by enabling spatial encoding through generating rapidly switching magnetic fields. However, these time-varying fields induce eddy currents in surrounding conductive structures, leading to gradient field distortions and imaging artifacts. In this study, we propose an automatic eddy current compensation method implemented on a field-programmable gate array (FPGA) platform. The approach employs iterative correction formulas for both linear gradient and <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> eddy fields, enabling real-time compensation. To enhance computational efficiency, a novel layout for the pre-emphasis (PE) unit is also introduced. Compared to conventional compensation techniques, the proposed FPGA-based solution offers significant improvements in implementation simplicity and system stability. Experimental results demonstrate that the residual direct- and cross-term eddy current fields are reduced to below 0.02%, equivalent to 4 <span><math><mrow><mi>μT</mi><mo>/</mo><mi>m</mi></mrow></math></span>, for a test gradient of 20 mT/m. Furthermore, the <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> eddy field is suppressed to below 0.1 <span><math><mi>μT</mi></math></span> when a <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> compensation coil is employed. These improvements effectively reduce ghosting artifacts in multi-slice gradient-echo (GRE) phantom images. The robustness of the method is further validated across various imaging sequences, including T1-weighted (T1w) and T2-weighted (T2w) protocols.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107951"},"PeriodicalIF":1.9,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922377","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 wireless bilateral transceiver coil based on volume decoupled resonators for a clinical MR mammography 一种基于体积解耦谐振器的双侧无线收发线圈，用于临床磁共振乳房x光检查

IF 1.9 3区化学 Q3 BIOCHEMICAL RESEARCH METHODS

Journal of magnetic resonance

Pub Date : 2025-08-14 DOI: 10.1016/j.jmr.2025.107941

Pavel Tikhonov , Aleksandr Fedotov , Georgiy Solomakha , Anna Hurshkainen

Wireless radiofrequency coils offer a valuable low cost solution for various MR applications due to several benefits, such as cable-free connection and compatibility with MR platforms of different vendors. Namely, for the purpose of clinical high-field human breast imaging several wireless transceiver coils are known to the date, those operational principle is based on inductive coupling with a body coil. These coils are commonly consist of a several volume resonators to perform bilateral breast imaging. Due to the electrically close location of volume resonators, strong inductive coupling is observed, resulting in the occurrence of hybrid modes. In principle, MR imaging using one of the hybrid modes is possible provided by the homogeneity of a

B_{1}^{+}

distribution. However, the question of influence of volume resonators coupling on wireless coil transmit efficiency and receive sensitivity was not previously studied. By this work, we performed study to understand this issue. The first wireless coil with decoupled resonators is developed, evaluated numerically and experimentally including in vivo study on healthy volunteers. Additionally in vivo images were obtained by a conventional receive array to compare with developed wireless coil. According to the obtained results, transmit efficiency and receive sensitivity of a pair of decoupled Helmholtz resonators of the configuration under study is at least 24% higher than for a pair of the same coupled resonators. In vivo images were also obtained using a six-channel receive array to compare with a developed wireless coil. Comparison with a multi-channel receive array have shown that SNR of the developed wireless coil is 10% lower, while time scanning was increased by 68%.

无线射频线圈为各种磁共振应用提供了有价值的低成本解决方案，因为它有几个优点，例如无电缆连接和与不同供应商的磁共振平台兼容。即，用于临床高场人体乳房成像的无线收发器线圈有几种，它们的工作原理都是基于与人体线圈的电感耦合。这些线圈通常由几个体积谐振器组成，用于双侧乳房成像。由于体积谐振器的电邻近位置，观察到强的电感耦合，导致混合模式的发生。原则上，由于B1+分布的均匀性，使用其中一种混合模式的MR成像是可能的。然而，体积谐振腔耦合对无线线圈发射效率和接收灵敏度的影响问题，以往没有研究过。通过这项工作，我们对这一问题进行了研究。开发了第一个具有解耦谐振器的无线线圈，并对其进行了数值和实验评估，包括对健康志愿者的体内研究。此外，通过传统的接收阵列获得体内图像，与开发的无线线圈进行比较。结果表明，采用该结构的一对解耦亥姆霍兹谐振器的发射效率和接收灵敏度比一对相同耦合谐振器的发射效率和接收灵敏度至少提高24%。使用六通道接收阵列也获得了体内图像，以与开发的无线线圈进行比较。与多通道接收阵列相比，所设计的无线线圈的信噪比降低了10%，扫描时间提高了68%。

{"title":"A wireless bilateral transceiver coil based on volume decoupled resonators for a clinical MR mammography","authors":"Pavel Tikhonov , Aleksandr Fedotov , Georgiy Solomakha , Anna Hurshkainen","doi":"10.1016/j.jmr.2025.107941","DOIUrl":"10.1016/j.jmr.2025.107941","url":null,"abstract":"<div><div>Wireless radiofrequency coils offer a valuable low cost solution for various MR applications due to several benefits, such as cable-free connection and compatibility with MR platforms of different vendors. Namely, for the purpose of clinical high-field human breast imaging several wireless transceiver coils are known to the date, those operational principle is based on inductive coupling with a body coil. These coils are commonly consist of a several volume resonators to perform bilateral breast imaging. Due to the electrically close location of volume resonators, strong inductive coupling is observed, resulting in the occurrence of hybrid modes. In principle, MR imaging using one of the hybrid modes is possible provided by the homogeneity of a <span><math><msubsup><mrow><mi>B</mi></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> distribution. However, the question of influence of volume resonators coupling on wireless coil transmit efficiency and receive sensitivity was not previously studied. By this work, we performed study to understand this issue. The first wireless coil with decoupled resonators is developed, evaluated numerically and experimentally including <em>in vivo</em> study on healthy volunteers. Additionally <em>in vivo</em> images were obtained by a conventional receive array to compare with developed wireless coil. According to the obtained results, transmit efficiency and receive sensitivity of a pair of decoupled Helmholtz resonators of the configuration under study is at least 24% higher than for a pair of the same coupled resonators. <em>In vivo</em> images were also obtained using a six-channel receive array to compare with a developed wireless coil. Comparison with a multi-channel receive array have shown that SNR of the developed wireless coil is 10% lower, while time scanning was increased by 68%.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107941"},"PeriodicalIF":1.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866961","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