Journal of magnetic resonance最新文献

{"title":"Dynamics of protein–water mixtures: insight from combined 1H spin-lattice and spin-spin relaxation studies of myoglobin","authors":"Kahinga Kamau ,&nbsp;Elzbieta Masiewicz ,&nbsp;Pedro José Sebastião ,&nbsp;Danuta Kruk","doi":"10.1016/j.jmr.2025.107993","DOIUrl":"10.1016/j.jmr.2025.107993","url":null,"abstract":"<div><div>Aiming to reveal the dynamical properties of highly concentrated protein–water systems and validating models of motion, ¹H spin-lattice and spin-spin relaxation experiments were performed for myoglobin – H₂O (40 % wt. of myoglobin) mixture versus temperature, from 268 K to 310 K. The spin-lattice relaxation studies were conducted using Fast Field Cycling (FFC) NMR relaxometry, in the frequency range from 10 kHz to 20 MHz. The comprehensive set of relaxation data was interpreted in terms of a superposition of relaxation contributions expressed in terms of Lorentzian spectral densities and corresponding to the time scales of the order of 10⁻⁶ s, 10⁻⁸–10⁻⁷ s and 10⁻⁹–10⁻⁸ s. The model was validated against the ¹H spin-spin relaxation data obtained from Time Domain (TD) NMR experiments at 18.5 MHz. The studies were complemented by ¹H spin-lattice (FFC NMR and TD NMR) and spin-spin (TD NMR) relaxation experiments for myoglobin – D₂O (40 % wt. of myoglobin) mixture. Bi-exponential spin-spin relaxation processes were observed for both myoglobin – H₂O and myoglobin – D₂O mixtures. A thorough comparison of the spin-lattice relaxation and spin-spin relaxation rates (both components) for the H₂O and D₂O containing mixtures led to the conclusion that the fast component of the spin-spin relaxation process originates from the pool of ¹H nuclei of myoglobin and is associated with slow dynamics of the protein, while the slow component of the spin-spin relaxation is a counterpart of the spin-lattice relaxation process (observed by FFC NMR and TD NMR) and they both reflect the dynamics of water molecules strongly bound to myoglobin (for myoglobin – H₂O) and a similar dynamics of myoglobin (for myoglobin – D₂O).</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 107993"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145663020","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}

{"title":"Accessing molecular motion activation parameters with 1H low-field time-domain NMR: Examples from glass transition in polymers","authors":"Bruno Trebbi ,&nbsp;Michele Pierigé ,&nbsp;Rodrigo Henrique dos Santos Garcia ,&nbsp;Francesca Martini ,&nbsp;Marco Geppi ,&nbsp;Eduardo Ribeiro deAzevedo","doi":"10.1016/j.jmr.2025.108008","DOIUrl":"10.1016/j.jmr.2025.108008","url":null,"abstract":"<div><div>A practical and accessible approach for analyzing complex molecular dynamics in heterogeneous systems from the temperature dependence of low-field ¹H time-domain NMR signals is presented. Based on Dipolar Filtered Magic Sandwich Echo (DFMSE) experiments, the method can be adapted to any measurement where the fraction of mobile or rigid segments can be monitored as a function of temperature. A theoretical framework based on the Anderson–Weiss model, using analytical expressions, is described, enabling the extraction of activation parameters and their distributions from low-field ¹H time-domain NMR data. A theoretical expression for the DFMSE signal as a function of temperature and filter time used in the experiment is derived, and an approximation is proposed to simplify the model while retaining the essential features of the DFMSE–temperature curves. Assuming Arrhenius or Vogel–Fulcher–Tammann (VFT) temperature dependence of correlation times, a relation is obtained linking the curve’s inflection temperature to the filter time, with activation parameters as fitting variables. This allows an initial estimation of activation parameters, later refined by fitting full DFMSE–temperature curves, including a distribution of values. The method is validated by determining activation parameters for motions associated with the glass transition dynamics of atactic polypropylene (aPP), yielding results consistent with previous NMR studies. It is further applied to a styrene–butadiene rubber (SBR) sample, whose parameters were independently obtained by field-cycling NMR, showing good agreement.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 108008"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784155","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}

{"title":"Mims Electron-Nuclear Double Resonance (ENDOR) with chirp microwave pulses","authors":"Marvin Lenjer ,&nbsp;Lena Schwieger ,&nbsp;Igor Tkach ,&nbsp;Fabian Hecker ,&nbsp;Marina Bennati","doi":"10.1016/j.jmr.2025.108005","DOIUrl":"10.1016/j.jmr.2025.108005","url":null,"abstract":"<div><div>We present a modification of the Mims Electron-Nuclear DOuble Resonance (ENDOR) experiment that uses microwave (MW) chirp pulses to enable broadband excitation in W-band (<span><math><mrow><mn>94</mn><mspace></mspace><mi>GHz</mi></mrow></math></span>) Electron Paramagnetic Resonance (EPR) spectroscopy and Fourier transform (FT) of the resulting stimulated echoes. The method is demonstrated on a nitroxide-¹⁹F model system and yields two-dimensional spectra that correlate hyperfine couplings with the EPR spectrum. In contrast to standard, time consuming and costly orientation-selective ENDOR measurements, this approach requires just one experiment at a single EPR resonance field position. At the same time, the resolution in the EPR dimension is increased. This provides additional information on the orientation of the hyperfine coupling tensor and enables the direct observation of chemical shielding anisotropy at W-band frequency. We analyze the effect of chirp pulses on the Mims blind spot function using CHirp Echo Epr SpectroscopY (CHEESY). Additionally, we illustrate that FT of spin echoes can be beneficial even without the availability of chirp pulses, using high-power rectangular MW pulses at Q-band (<span><math><mrow><mn>34</mn><mspace></mspace><mi>GHz</mi></mrow></math></span>). Overall, our results suggest that the combination of Mims ENDOR spectroscopy with FT of MW echoes can be a valuable method to obtain detailed information on electron-nuclear spin interaction tensors and will be potentially useful to disentangle complex, multi-component ENDOR spectra.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 108005"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145746320","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}

{"title":"Reconfigurable animal bed–EPR resonator assembly for multimodal co-registration","authors":"Oxana Tseytlin ,&nbsp;Michael Sestito ,&nbsp;Timothy D. Eubank ,&nbsp;Valery V. Khramtsov ,&nbsp;Benoit Driesschaert ,&nbsp;Brian A. Boone ,&nbsp;Mark Tseytlin","doi":"10.1016/j.jmr.2025.107995","DOIUrl":"10.1016/j.jmr.2025.107995","url":null,"abstract":"<div><div>A modular animal bed–resonator assembly (ABRA) platform is presented for multimodal preclinical co-registration of electron paramagnetic resonance imaging (EPRI) and magnetic resonance imaging (MRI). The reconfigurable “Lego-style” design enables effortless exchange and repositioning of resonator components to support a wide range of frequencies and achieve critical coupling conditions, tailored to the animal's type and size. The ABRA platform also addresses the need for stable EPRI of deep-lying organs in small animal disease models, such as pancreatic cancer, using advanced rapid-scan (RS) technology. RS EPRI enhances sensitivity by enabling higher excitation powers without saturating the spin system. However, the use of increased power exacerbates the challenge of maintaining critical coupling throughout the experiment. To improve data acquisition stability, the EPR resonator and coupling loop are constructed from coaxial cable segments, with the electric field uniformly confined between the inner and outer conductors to minimize undesired electric interactions with the animal. Shielding, along with the absence of touch-sensitive components such as lumped capacitors, contributes to stable data acquisition. Fiducial markers integrated into the bed, visible in both modalities, facilitate automated spatial alignment. The 3D-printed bed is designed to be compatible with affordable preclinical small-bore 1 T MRI systems. Co-registration is performed using a standard MATLAB-based image processing workflow that includes segmentation, fiducial selection, and rigid-body transformation. In vivo evaluation of tuning and coupling performance was conducted using mice bearing pancreatic adenocarcinoma or non-tumor-bearing mice. Imaging results, including co-registration performance, are reported for the non-tumor-bearing mice. The ABRA components and data processing using standard MATLAB tools can be easily replicated in laboratories with minimal engineering expertise.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 107995"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145650651","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}

{"title":"Variable spacing Fast-T1ρ for the analysis of fast relaxing species at low-field","authors":"Alastair D. Robinson ,&nbsp;Jordan A. Ward-Williams ,&nbsp;Matthias Appel ,&nbsp;Andrew J. Sederman ,&nbsp;Mick D. Mantle ,&nbsp;Lynn F. Gladden","doi":"10.1016/j.jmr.2025.108002","DOIUrl":"10.1016/j.jmr.2025.108002","url":null,"abstract":"<div><div><em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> is a powerful analytical technique capable of probing motions on the timescale of molecular dynamics. Conventional <em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> approaches are performed on high-field NMR magnets (typically <span><math><mrow><mo>&gt;</mo><mn>2</mn></mrow></math></span> T) and rely on step-by-step data acquisition, resulting in relatively long experiments and acquisitions that are affected by non-negligible internal gradient effects and strict Specific Absorption Rate limits. The work presented herein reports the development of novel one- and two-dimensional Fast-<em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> pulse sequences on a 2 MHz benchtop NMR spectrometer. The developed method enables the observation of fast-relaxing species down to the millisecond timescale through application of a variably-spaced spin-lock duration array with delay spacings as short as 100 <span><math><mi>μ</mi></math></span>s. Fast-<em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> and Fast-<em>T</em><span><math><msub><mrow></mrow><mrow><mn>1</mn></mrow></msub></math></span>-<em>T</em><span><math><msub><mrow></mrow><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></math></span> pulse sequences have been developed which show significantly faster acquisition relative to conventional <em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span>, illustrated with a 6-fold and 25-fold reduction in experiment time respectively. These techniques were demonstrated to be robust and accurate with measured <em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> values for bulk glycerol showing a maximum difference of 5.4% between Fast-<em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> and conventional <em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> experiments. The power of this method is exemplified through the simultaneous observation of multiple relaxation environments within a porous <span><math><mi>γ</mi></math></span>-Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> sample imbibed with an ethanol:water mixture, where <em>T</em><span><math><msub><mrow></mrow><mrow><mi>1ρ</mi></mrow></msub></math></span> relaxation rates of two orders of magnitude difference (2.4 ms to 370 ms) were captured.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 108002"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784160","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}

{"title":"Optimal excitation of single mode resonators: demonstration with a 3 T MRI metasolenoid","authors":"Dmitrii Tikhonenko ,&nbsp;Kaizad Rustomji ,&nbsp;Christophe Vilmen ,&nbsp;Arnaud Durand ,&nbsp;Georges Nouari ,&nbsp;Stefan Enoch ,&nbsp;David Bendahan ,&nbsp;Redha Abdeddaim ,&nbsp;Marc Dubois","doi":"10.1016/j.jmr.2025.107992","DOIUrl":"10.1016/j.jmr.2025.107992","url":null,"abstract":"<div><div>Wireless passive resonators have been developed to inductively couple to the birdcage body coil. Such systems have been explored in the form of ceramic resonators with high permittivity but also with metamaterial or metasurface devices that can exhibit resonant behaviour at a given Larmor frequency. The resonant focusing of the radiofrequency field is used to lower the input power during transmission and improve the sensitivity of the body coil during reception. The gain is only obtained in a limited volume located within or close to the resonant structure. Typically, such passive devices do not support parallel imaging and demonstrated limited SNR enhancement compared to dense multichannel receive arrays<em>.</em> Nonetheless, these resonators have seen recent development with applications to wrist or breast MRI mostly in 1.5 T MRI scanners. Here we propose to design, build, and study a metasolenoid resonator operating at 3 T. The metasolenoid was characterized on phantom to validate the B₁ efficiency increase with respect to the birdcage polarization excitation. We reported a high B₁ efficiency gain for circularly (3.2-fold) and linearly (5.8-fold) polarized excitation. Consequently, and according to analytical calculations, we demonstrated that when excited with linearly polarized excitation, the metasolenoid had a B₁ efficiency 26 % higher when excited by the default circularly polarized excitation. Numerical simulations on voxel model showed that in presence of the resonator the B₁ efficiency gain normalized by the maximum local SAR was significantly improved when introducing the metasolenoid but the influence of the excitation polarization was reduced to a few percent.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"382 ","pages":"Article 107992"},"PeriodicalIF":1.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145546583","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}

{"title":"Significant acceleration of solid-state NMR simulations via three-angle powder averaging","authors":"Elijah Burlinson ,&nbsp;Frédéric A. Perras","doi":"10.1016/j.jmr.2025.107966","DOIUrl":"10.1016/j.jmr.2025.107966","url":null,"abstract":"<div><div>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 <em>γ</em>. Traditionally, a carousel average is performed to integrate over <em>γ</em>, 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 <em>γ</em>-averaging into the main powder average to eliminate redundant calculation of resonance frequencies.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107966"},"PeriodicalIF":1.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048240","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}

{"title":"Sample-accessible multi-resonance X-band EPR triple ring resonator","authors":"Chun Him Lee ,&nbsp;Meltem Elitaş ,&nbsp;Jan G. Korvink ,&nbsp;Mazin Jouda","doi":"10.1016/j.jmr.2025.107988","DOIUrl":"10.1016/j.jmr.2025.107988","url":null,"abstract":"<div><div>Micro-resonators downsize their resonating structures, reaching frequencies required for electron paramagnetic resonance (EPR) spectroscopy, thus allowing sensitive detection of mass-limited samples. Planar resonators provide accessibility of the sample space, allowing <em>in situ</em> and <em>operando</em> experiments for convenient characterization with access to environmental parameters such as UV radiation, gas and liquid flow, and better temperature gradient control. We report a novel triple-ring resonating structure that exploits the benefits of sample accessibility and its miniaturized structure. It offers three simultaneously operating X-band channels (8<!--> <!-->GHz to 11<!--> <!-->GHz) with a real-time accessible 50<!--> <!-->nL sample volume for each channel, with a maximum spin sensitivity of <span><math><mrow><mn>1</mn><mo>.</mo><mn>18</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>8</mn></mrow></msup></mrow></math></span> Spin/Hz^1/2. By cascading the ring resonators, we improve the quality factor of each resonance by reflecting and confining the electromagnetic energy by the neighboring rings. The Q-factor of the center resonance at 9.45<!--> <!-->GHz with the enhancement of 2 passive reflectors reaches 73. Three relative translations allow a wide range of tuning, matching, suppressing, and isolating the resonances. While the introduced resonator exhibits three resonances only, it can be readily upscaled to feature more resonances, thus opening the door to high-throughput parallel EPR spectroscopy.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107988"},"PeriodicalIF":1.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145314445","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}

{"title":"Rapid MRI profiling of two-phase flow in porous media","authors":"Quirine Krol ,&nbsp;Matthew E. Skuntz ,&nbsp;Sarah L. Codd ,&nbsp;Joseph D. Seymour","doi":"10.1016/j.jmr.2025.107971","DOIUrl":"10.1016/j.jmr.2025.107971","url":null,"abstract":"<div><div>Two-phase flow in porous media underpins a wide range of natural and industrial processes, but its transient dynamics remain challenging to capture at the spatiotemporal resolution required to resolve pore-scale phenomena. We present a method for rapid one-dimensional (1D) magnetic resonance imaging (MRI) profiling that simultaneously acquires spin-echo signal intensity and phase angle profiles with <span><math><mrow><mn>98</mn><mspace></mspace><mi>μm</mi></mrow></math></span> spatial and <span><math><mrow><mn>20</mn><mspace></mspace><mi>ms</mi></mrow></math></span> temporal resolution. The technique enables real-time observation of both fluid saturation and velocity fluctuations across a porous medium. We demonstrate its capabilities through three benchmark experiments: (1) controlled drainage and filling of a cylindrical tank, (2) buoyancy-driven rise of oil droplets in water, and (3) drainage and imbibition of a model porous medium. The results reveal dynamic interfacial behavior, velocity fluctuations linked to Haines jumps, and flow-dependent signal attenuation effects. We further analyze the relationship between flow velocity and signal attenuation in porous media using stop-motion dual-echo experiments. Our findings show that rapid magnetic resonance imaging provides a sensitive tool for probing two-phase flow dynamics, with implications for understanding complex fluid behavior in porous materials.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107971"},"PeriodicalIF":1.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145305131","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}

{"title":"Effect of the spin-locking B1 radiofrequency field strength on the signal enhancement with Magic Sandwich Echo sequence","authors":"Eloïse Mougel ,&nbsp;Hélène Ratiney ,&nbsp;Eric Van Reeth ,&nbsp;Kevin Tse Ve Koon ,&nbsp;Olivier Beuf ,&nbsp;Denis Grenier","doi":"10.1016/j.jmr.2025.107973","DOIUrl":"10.1016/j.jmr.2025.107973","url":null,"abstract":"<div><div>Contrast methods based on dipolar coupling are of great interest for imaging tissues containing large macromolecules, such as myelin. Most of these conventional methods deal with various “relaxation” phenomena influenced by dipolar coupling such as inhomogeneous magnetization transfer. In this work we propose to investigate the benefit of using another method, called magic sandwich echo (MSE), which allows direct modulation of the dipolar coupling (<em>H</em>_<em>d</em>) as described by the work of Matsui and the Redfield theory. To verify the potential of this method in biological tissue, we first proposed an experimental model for dipolar coupling modulation in an <em>ex vivo</em> tendon (as a highly anisotropic tissue) and used it to prove <em>H</em>_<em>d</em> modulation by varying the amplitude of the spin-lock radiofrequency pulse of this sequence. We then proposed a potential <em>in vivo</em> usable metric, directly related to the residual amount of <em>H</em>_<em>d</em>, which we called MaSteR for Magic sandwich echo to Stimulated echo ratio, as it is based on the ratio of the signal acquired with the MSE sequence and a stimulated echo sequence. First, we show that the higher <em>H</em>_<em>d</em>, the more effective the spin-lock radiofrequency amplitude. We measured with MaSteR that the change in radiofrequency amplitude allowed us to distinguish between different <em>H</em>_<em>d</em> intensities, with a greater MaSteR when <em>H</em>_<em>d</em> is higher.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"381 ","pages":"Article 107973"},"PeriodicalIF":1.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145350838","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}