Pub Date : 2025-12-01Epub Date: 2025-09-13DOI: 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.
{"title":"A simple algorithm to suppress diagonal peaks in high-resolution homonuclear chemical shift correlation NMR spectra","authors":"Shengyu Zhang , Jhinuk Saha , Yuchen Li , Xinhua Peng , Ryan P. McGlinchey , Ayyalusamy Ramamoorthy , Riqiang Fu","doi":"10.1016/j.jmr.2025.107967","DOIUrl":"10.1016/j.jmr.2025.107967","url":null,"abstract":"<div><div>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 <sup>13</sup>C,<sup>15</sup>N labeled α-synuclein amyloid fibrils and aquaporin Z membrane protein samples.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107967"},"PeriodicalIF":1.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093324","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}
Pub Date : 2025-11-01Epub Date: 2025-08-08DOI: 10.1016/j.jmr.2025.107938
Marthe Millen , Nicholas Alaniva , Snædís Björgvinsdóttir , Alexander Däpp , Ioannis Gr. Pagonakis , Wolfgang Harneit , Alexander B. Barnes
Dynamic nuclear polarization (DNP) relies on the transfer of electron polarization to nuclei through microwave irradiation and is typically performed under cryogenic magic-angle spinning (MAS) at high magnetic fields. Gyrotrons are commonly used microwave sources in DNP because of their ability to produce high-power microwaves over a broad frequency range. An important step towards a more in-depth understanding of DNP mechanisms and rational optimization of DNP performance is the access to instrumentation, which can provide information about the DNP process. Continuous wave (CW) electron paramagnetic resonance (EPR) can reveal important information on the electron spin system during DNP experiments. Here, we present a dual CW EPR/DNP spectrometer operated under MAS at 100 K and 7 T using a frequency-agile 198 GHz gyrotron. The measured sensitivity for CW EPR at 198 GHz using an MAS stator is 4 1013 spins/(G). To illustrate the electron and nuclear detection capabilities of our setup, DNP profiles and CW EPR spectra of a diamond powder and a trityl sample were recorded under the same conditions, specifically at 100 K and under MAS.
{"title":"Cryogenic magic-angle spinning continuous wave EPR and DNP spectroscopy at 7 T with a gyrotron","authors":"Marthe Millen , Nicholas Alaniva , Snædís Björgvinsdóttir , Alexander Däpp , Ioannis Gr. Pagonakis , Wolfgang Harneit , Alexander B. Barnes","doi":"10.1016/j.jmr.2025.107938","DOIUrl":"10.1016/j.jmr.2025.107938","url":null,"abstract":"<div><div>Dynamic nuclear polarization (DNP) relies on the transfer of electron polarization to nuclei through microwave irradiation and is typically performed under cryogenic magic-angle spinning (MAS) at high magnetic fields. Gyrotrons are commonly used microwave sources in DNP because of their ability to produce high-power microwaves over a broad frequency range. An important step towards a more in-depth understanding of DNP mechanisms and rational optimization of DNP performance is the access to instrumentation, which can provide information about the DNP process. Continuous wave (CW) electron paramagnetic resonance (EPR) can reveal important information on the electron spin system during DNP experiments. Here, we present a dual CW EPR/DNP spectrometer operated under MAS at 100 K and 7 T using a frequency-agile 198 GHz gyrotron. The measured sensitivity for CW EPR at 198 GHz using an MAS stator is 4 <span><math><mo>×</mo></math></span> 10<sup>13</sup> spins/(G<span><math><msqrt><mrow><mi>H</mi><mi>z</mi></mrow></msqrt></math></span>). To illustrate the electron and nuclear detection capabilities of our setup, DNP profiles and CW EPR spectra of a diamond powder and a trityl sample were recorded under the same conditions, specifically at 100 K and under MAS.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107938"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866960","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}
Pub Date : 2025-11-01Epub Date: 2025-08-08DOI: 10.1016/j.jmr.2025.107940
Melisa L. Gimenez , Pablo Jimenez , Leonardo A. Pedraza Pérez , Diana Betancourth , Analia Zwick , Gonzalo A. Álvarez
Neurological diseases often result in changes at microscopic scales in the nervous system, emphasising the need for non-invasive imaging techniques that can quantify these alterations as potential biomarkers for diagnosis. Diffusion-weighted magnetic resonance imaging (DWI), particularly using modulated gradient spin-echo (MGSE) sequences, has significantly advanced in revealing tissue microstructure by probing molecular diffusion. Among the MGSE sequences, the Non-uniform Oscillating Gradient Spin-Echo (NOGSE) sequence generates a contrast based on selective microstructure sizes through a signal decay-shift, rather than probing conventional decay rates. In this study, we evaluate the performance of NOGSE in estimating microstructure sizes using a preclinical MRI scanner. Our results show that while sharp, instantaneous gradient modulations maximise the decay-shift, smooth gradient modulations still provide meaningful contrast. Through a combination of phantom experiments, numerical simulations and information-theoretic analysis, we optimise NOGSE parameters for accurate microstructural size estimation under both sharp and smooth gradient modulations. We identify optimal NOGSE parameters that are compatible with preclinical hardware constraints, providing reliable microstructure size characterisation. Especially smooth gradient modulations expand the range of compatible MRI scanners and are almost suitable for in-vivo applications. These findings represent a step toward developing quantitative imaging tools for probing microstructural features in diffusion-weighted magnetic resonance imaging.
{"title":"Optimisation and impact of gradient waveform modulation on Non-uniform Oscillating Gradient Spin-Echo sequences for microstructural characterisation","authors":"Melisa L. Gimenez , Pablo Jimenez , Leonardo A. Pedraza Pérez , Diana Betancourth , Analia Zwick , Gonzalo A. Álvarez","doi":"10.1016/j.jmr.2025.107940","DOIUrl":"10.1016/j.jmr.2025.107940","url":null,"abstract":"<div><div>Neurological diseases often result in changes at microscopic scales in the nervous system, emphasising the need for non-invasive imaging techniques that can quantify these alterations as potential biomarkers for diagnosis. Diffusion-weighted magnetic resonance imaging (DWI), particularly using modulated gradient spin-echo (MGSE) sequences, has significantly advanced in revealing tissue microstructure by probing molecular diffusion. Among the MGSE sequences, the Non-uniform Oscillating Gradient Spin-Echo (NOGSE) sequence generates a contrast based on selective microstructure sizes through a signal decay-shift, rather than probing conventional decay rates. In this study, we evaluate the performance of NOGSE in estimating microstructure sizes using a preclinical MRI scanner. Our results show that while sharp, instantaneous gradient modulations maximise the decay-shift, smooth gradient modulations still provide meaningful contrast. Through a combination of phantom experiments, numerical simulations and information-theoretic analysis, we optimise NOGSE parameters for accurate microstructural size estimation under both sharp and smooth gradient modulations. We identify optimal NOGSE parameters that are compatible with preclinical hardware constraints, providing reliable microstructure size characterisation. Especially smooth gradient modulations expand the range of compatible MRI scanners and are almost suitable for <em>in-vivo</em> applications. These findings represent a step toward developing quantitative imaging tools for probing microstructural features in diffusion-weighted magnetic resonance imaging.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107940"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842914","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}
Pub Date : 2025-11-01Epub Date: 2025-08-12DOI: 10.1016/j.jmr.2025.107953
Dominik Gendreizig , Christina Elsner , Svetlana Kucher , Gunnar Jeschke , Alistair J. Fielding , Enrica Bordignon
Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labelling provides information on structure and dynamics of biomolecules. Increasing the availability of spin labels with different properties is an elegant way to foster a more accurate analysis of the EPR data in relation to the biological problem investigated. In this study, we present a comparative investigation of labelling efficiency, surface accessibility, site specificity and width of the distance distributions obtained on two proteins with the nitroxide-based bromoacrylaldehyde spin label (BASL) versus the two commercial spin labels MTSL (methanethiosulfonate spin label) and MAP (maleimido proxyl). Based on the predicted distances from a rotamer library approach and on the experimental distance distributions, BASL is shown to provide generally narrower distance distributions compared to the other nitroxide labels. The exquisite surface specificity of BASL with respect to MAP could be successfully exploited to selectively label surface cysteines in proteins containing a high number of native cysteines. In addition, the distinct site-reactivity of BASL and MAP towards two surface-exposed cysteines was leveraged for orthogonal labelling strategies with nitroxide and gadolinium labels.
{"title":"Specificity and reactivity of bromoacrylaldehyde spin labels","authors":"Dominik Gendreizig , Christina Elsner , Svetlana Kucher , Gunnar Jeschke , Alistair J. Fielding , Enrica Bordignon","doi":"10.1016/j.jmr.2025.107953","DOIUrl":"10.1016/j.jmr.2025.107953","url":null,"abstract":"<div><div>Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labelling provides information on structure and dynamics of biomolecules. Increasing the availability of spin labels with different properties is an elegant way to foster a more accurate analysis of the EPR data in relation to the biological problem investigated. In this study, we present a comparative investigation of labelling efficiency, surface accessibility, site specificity and width of the distance distributions obtained on two proteins with the nitroxide-based bromoacrylaldehyde spin label (BASL) versus the two commercial spin labels MTSL (methanethiosulfonate spin label) and MAP (maleimido proxyl). Based on the predicted distances from a rotamer library approach and on the experimental distance distributions, BASL is shown to provide generally narrower distance distributions compared to the other nitroxide labels. The exquisite surface specificity of BASL with respect to MAP could be successfully exploited to selectively label surface cysteines in proteins containing a high number of native cysteines. In addition, the distinct site-reactivity of BASL and MAP towards two surface-exposed cysteines was leveraged for orthogonal labelling strategies with nitroxide and gadolinium labels.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"380 ","pages":"Article 107953"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860268","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}
Pub Date : 2025-11-01Epub Date: 2025-08-26DOI: 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.
{"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":"2025-11-01","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}
Pub Date : 2025-11-01Epub Date: 2025-08-18DOI: 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 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 , for a test gradient of 20 mT/m. Furthermore, the eddy field is suppressed to below 0.1 when a 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.
{"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":"2025-11-01","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}
Pub Date : 2025-11-01Epub Date: 2025-08-19DOI: 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 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":"2025-11-01","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}
Pub Date : 2025-11-01Epub Date: 2025-08-25DOI: 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.
{"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":"2025-11-01","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}
Pub Date : 2025-11-01Epub Date: 2025-08-14DOI: 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 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%.
{"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":"2025-11-01","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}
Pub Date : 2025-10-01Epub Date: 2025-08-18DOI: 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
{"title":"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]","authors":"Alexander M. Funk , Brian L. Anderson , Xiaodong Wen , Thomas Hever , Chalermchai Khemtong , Zoltan Kovacs , A. Dean Sherry , Craig R. Malloy","doi":"10.1016/j.jmr.2025.107942","DOIUrl":"10.1016/j.jmr.2025.107942","url":null,"abstract":"","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107942"},"PeriodicalIF":1.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144884681","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}
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