Journal of magnetic resonance最新文献

{"title":"Removing magnetic field noise from NMR spectra: Reference deconvolution revisited","authors":"Alexander Karabanov ,&nbsp;Eugeny Kryukov ,&nbsp;Gareth Morris ,&nbsp;Jeremy Good","doi":"10.1016/j.jmr.2025.107937","DOIUrl":"10.1016/j.jmr.2025.107937","url":null,"abstract":"<div><div>Reference deconvolution, a powerful mathematical tool for removing the effects of imperfections of the main magnetic field on NMR spectra, is revisited in the context of strong static and dynamic field perturbations. The theoretical basis and experimental evidence for the high efficiency of reference deconvolution for strong magnetic field distortions in basic liquid-state one- and two-dimensional NMR are given.</div><div>In particular, in 2D NMR, we utilise our observation that a strong static inhomogeneity of the main magnetic field suppresses anti-echo coherence transfer contributions, enabling reference deconvolution to be applied to the remaining echo contributions, in each indirect increment separately, in a manner similar to 1D NMR. We show that, in both 1D and 2D NMR, reference deconvolution enables one to remove the vibrational artefacts of cold head operation in cryogen-free magnets.</div><div>This extends the applicability of reference deconvolution in multi-dimensional NMR and advances cryogen-free technology in liquid-state NMR.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107937"},"PeriodicalIF":1.9,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144723392","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":"Gradient coil design for a 0.23 T NICU MRI system using an improved two-step Target-Field Method with enhanced linearity and compact design","authors":"Jinhao Liu ,&nbsp;Miutian Wang ,&nbsp;Wenchen Wang ,&nbsp;Yaohui Wang ,&nbsp;Weimin Wang ,&nbsp;Feng Liu","doi":"10.1016/j.jmr.2025.107936","DOIUrl":"10.1016/j.jmr.2025.107936","url":null,"abstract":"<div><div>This study presents an optimized gradient coil design for a miniature 0.23 T MRI system, aimed at improving absolute and relative magnetic field linearity while accommodating various gradient thicknesses. The design uses a two-step optimization approach: the first step uses Tikhonov regularization to solve a linear problem, providing a stable solution, and the second step refines the solution through nonlinear constrained optimization to further enhance field linearity. An explicit objective function for the inductance matrix of biplanar gradient coils is simplified to enhance computational efficiency. Validation through MATLAB and COMSOL finite element analysis showed excellent performance. Imaging experiments were conducted on small animals (cats and dogs, whose sizes are similar to neonates) while awaiting ethical approval for human neonatal studies. Results demonstrated that all gradient coils achieved absolute and relative linearity errors below 5%. Cubic phantom scans showed slight displacement at the edges, but the structured phantom MRI lines align precisely with the physical markers, indicating negligible geometric distortion. The shield design maintained Z-leakage fields below 5 Gauss, with eddy current compensation achieving a 90% reduction (residual X/Y-gradient <span><math><mo>&lt;</mo></math></span> 0.05%, Z-gradient <span><math><mo>&lt;</mo></math></span> 0.20%). T1 and T2-weighted images depicted clear brain structures, while FLAIR and STIR sequences effectively highlighted tissue changes. The proposed gradient coil design method significantly improves absolute and relative linearity while accommodating various gradient thicknesses, demonstrating strong resistance to interference and broad applicability. The comprehensive design-to-manufacturing process ensures optimal parameter selection, resulting in high-quality imaging across multiple MRI sequences. This design demonstrates strong potential for precise <em>in-vivo</em> brain imaging in further NICU applications.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107936"},"PeriodicalIF":2.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704306","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 flow characterization measurements using a modified CPMG measurement with incremented echo times, phase cycling and filtering","authors":"Sebastian J. Richard,&nbsp;Benedict Newling,&nbsp;Bruce J. Balcom","doi":"10.1016/j.jmr.2025.107923","DOIUrl":"10.1016/j.jmr.2025.107923","url":null,"abstract":"<div><div>We recently demonstrated a magnetic resonance methodology for measuring and characterizing various pipe flows, using a series of individually-acquired spin echoes at different <span><math><mi>τ</mi></math></span>. The key advantage of our approach lies in the simplicity of the experiment, MR hardware, and data processing. However, acquiring each spin echo separately results in prolonged measurement times. To address this, we employ an echo-train approach to acquire the series of variable <span><math><mi>τ</mi></math></span> spin echoes. By incrementing CPMG echo pulse spacings within the echo train and implementing a four-step phase cycling scheme to suppress coherence pathway effects, we obtain the same echo phase and magnitude response to flow as a function of <span><math><msup><mrow><mi>τ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> as in our original method, without requiring individual echo acquisitions. This new approach significantly reduces the number of required experiments, shortening measurement time by a factor of <span><math><mrow><mn>1</mn><mo>/</mo><mi>N</mi></mrow></math></span>, where <span><math><mi>N</mi></math></span> is the number of utilized echoes per echo train. Our phase cycling strategy, combined with incremented pulse spacings, enables <span><math><mrow><mi>N</mi><mo>=</mo><mn>3</mn></mrow></math></span> in our benchtop flow measurement. Validation experiments with Newtonian and shear-thinning fluids confirm that the new echo-train technique yields results consistent with the original approach of acquiring each spin echo separately.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107923"},"PeriodicalIF":2.0,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655402","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":"Broadband excitation of nuclei spin by refocused feedback","authors":"Vishesh Kaushik,&nbsp;Navin Khaneja","doi":"10.1016/j.jmr.2025.107927","DOIUrl":"10.1016/j.jmr.2025.107927","url":null,"abstract":"<div><div>The ability to precisely control the spin states of nuclei in an ensemble is critical for advancing NMR spectroscopy. In this paper, we present a technique referred to as <em>Refocused Feedback</em> to construct RF pulses that enable uniform transitions of spin states across the continuous spectrum of chemical shifts. It is used to achieve uniform broadband excitation of nuclei ensemble. The RF pulses are designed based on strategically selected hypothetical initial and final conditions, with the pulse phase iteratively updated according to the feedback control law. The control sequence is then transformed for applications in real systems. This approach ensures uniform excitation across the continuous range of chemical shifts while digitally constructing the pulse sequence from discrete samples.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107927"},"PeriodicalIF":2.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695090","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":"Protecting air/moisture-sensitive samples using perdeuterated paraffin wax for solid-state NMR experiments under magic-angle spinning","authors":"Emma A. Foley ,&nbsp;Joseph F. Thuma ,&nbsp;Jacob Mayer ,&nbsp;Mita Halder ,&nbsp;Wenyu Huang ,&nbsp;Frédéric A. Perras ,&nbsp;Damien B. Culver ,&nbsp;Takeshi Kobayashi","doi":"10.1016/j.jmr.2025.107935","DOIUrl":"10.1016/j.jmr.2025.107935","url":null,"abstract":"<div><div>Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a powerful technique for materials characterization, yet its application to air- and moisture-sensitive materials is often hindered by the difficulty in maintaining an inert environment during magic-angle spinning (MAS). This is particularly true for fast-MAS rotors that do not generally provide tight seals. Herein, we present a generalizable approach employing perdeuterated paraffin waxes—<em>n</em>-icosane-d42 and <em>c</em>-dodecane-d24—as protective embedding media to analyze sensitive organometallic catalysts using SSNMR. We demonstrate that these waxes significantly slow oxidative degradation under MAS conditions. Weak background ¹H and ¹³C NMR signals from the waxes are effectively suppressed using double-quantum filtration and cross-polarization techniques. These findings offer a robust method for expanding the scope of SSNMR to air-sensitive systems, with implications for the structural study of reactive materials and catalysts.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107935"},"PeriodicalIF":2.0,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632715","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":"Towards complete suppression of diagonal peaks in solid-state MAS NMR homonuclear chemical shift correlation spectra","authors":"Shengyu Zhang ,&nbsp;Yuchen Li ,&nbsp;Yansheng Ye ,&nbsp;Fang Tian ,&nbsp;Xinhua Peng ,&nbsp;Riqiang Fu","doi":"10.1016/j.jmr.2025.107926","DOIUrl":"10.1016/j.jmr.2025.107926","url":null,"abstract":"<div><div>The feasibility of applying the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed to generate sine- and cosine-modulations of the chemical shift difference between the spin-diffused signals, enabling the quadrature detection in the indirect dimension. Meanwhile, all signals not involved in polarization transfer are refocused at the center of the indirect dimension. A data processing algorithm is developed to extract and suppress these spin-echo refocused signals without affecting nearby spin-diffused cross peaks. The processed spectrum is then converted into a conventional two-dimensional homonuclear chemical shift correlation spectrum, free of diagonal peaks. The effectiveness of this method is illustrated using a uniformly ¹³C-labeled Fmoc-leucine sample and a sample of human Atg8 homolog LC3B, directly conjugated to the amino headgroup of phosphatidylethanolamine (PE) lipids in liposomes.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107926"},"PeriodicalIF":2.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518107","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":"A mathematical model of NMR transverse relaxation for pore size distribution estimation in porous media","authors":"S. Morales-Chávez ,&nbsp;M.A. Valdez-Grijalva ,&nbsp;M.A. Díaz-Viera ,&nbsp;E. Lucas-Oliveira ,&nbsp;T.J. Bonagamba","doi":"10.1016/j.jmr.2025.107922","DOIUrl":"10.1016/j.jmr.2025.107922","url":null,"abstract":"<div><div>Nuclear Magnetic Resonance (NMR) is a widely useful technique for studying porous media. Of particular interest are transverse relaxation times (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), which are often associated with pore size when surface relaxation is the dominant mechanism. Under specific physical assumptions, a distribution of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> can be used to infer the pore size distribution (PSD). However, in real porous rocks, a combination of diffusion and relaxation mechanisms complicates this interpretation. Despite recent advancements in industrial applications, conventional models frequently rely on simplifying assumptions, particularly when pore size is considered in the fast diffusion regime. This results in the neglect of transverse bulk relaxation (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn><mi>B</mi></mrow></msub></math></span>) effects, leading to underestimations of pore sizes. To address this, numerical methods, particularly the Finite Element Method (FEM), offer flexibility in modeling symmetric geometries while significantly reducing computational complexity. This paper presents a mathematical NMR model and numerical implementation based on FEM to simulate transverse magnetization signals for a PSD, validated with semi-analytical solutions and applied to synthetic and real samples, such as Berea sandstone. Additionally, a change of variable in the Inverse Laplace Transform (ILT) model is introduced for the direct PSD estimation, demonstrating a strong agreement between experimental and simulated data.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"379 ","pages":"Article 107922"},"PeriodicalIF":2.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588622","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":"Accurate image reconstruction from reduced data in pulsed electron paramagnetic resonance imaging","authors":"Zheng Zhang ,&nbsp;Boris Epel ,&nbsp;Buxin Chen ,&nbsp;Dan Xia ,&nbsp;Emil Y. Sidky ,&nbsp;Howard Halpern ,&nbsp;Xiaochuan Pan","doi":"10.1016/j.jmr.2025.107920","DOIUrl":"10.1016/j.jmr.2025.107920","url":null,"abstract":"<div><h3>Objective:</h3><div>We investigate and develop algorithms for reconstructing effective probe-density images, and then for obtaining oxygen-concentration images, from data of a subject collected at sparse views (SVs) or over a limited-angular range (LAR) for possibly achieving fast pulsed electron paramagnetic resonance imaging (EPRI). We refer to the effective probe-density image simply as the EPR image in the work.</div></div><div><h3>Methods:</h3><div>The reconstruction problem of EPR images from SV or LAR data in pulsed EPRI is formulated as an optimization program that includes a constraint either on the total variation (TV) or on the directional-TVs (DTVs) of the EPR image. Two algorithms, referred to as TV and DTV algorithms, are developed then for reconstruction of EPR images, respectively, from SV and LAR data through solving the respective optimization programs. Oxygen-concentration image is estimated subsequently from the EPR images reconstructed.</div></div><div><h3>Results:</h3><div>Using numerical studies with simulated data of a digital phantom and also with real data of a physical phantom and a mouse model, we demonstrate the potential of the TV and DTV algorithms that yield, respectively, from SV and LAR data, numerically accurate EPR and oxygen-concentration images.</div></div><div><h3>Conclusion:</h3><div>The TV and DTV algorithms developed can yield numerically accurate EPR and oxygen-concentration images, respectively, from SV and LAR data in pulsed EPRI.</div></div><div><h3>Significance:</h3><div>The work may yield insights into the design of scans with minimized scanning time, thus potentially enabling basic and preclinical <em>in vivo</em> studies with fast pulsed EPRI.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107920"},"PeriodicalIF":2.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548629","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":"Using solid-state MRI and a double-tuned RF coil to quantify bone matrix and mineral densities in rat bones","authors":"Victor B. Kassey ,&nbsp;Matthias Walle ,&nbsp;Diana Yeritsyan ,&nbsp;Daniel V. Kassey ,&nbsp;Yaotang Wu ,&nbsp;Brian D. Snyder ,&nbsp;Edward K. Rodriguez ,&nbsp;Jerome L. Ackerman ,&nbsp;Ara Nazarian","doi":"10.1016/j.jmr.2025.107925","DOIUrl":"10.1016/j.jmr.2025.107925","url":null,"abstract":"<div><div>Quantitative information on the composition of bone, specifically the content of calcium phosphate mineral and organic matrix, is essential for accurate diagnosis of metabolic bone diseases such as osteoporosis, osteomalacia, and renal osteodystrophy, as well as for differentiating among these conditions. Conventional MRI fails to provide this information because these substances are solid and, therefore, yield no signal in conventional MRI scans, which typically employ spin or gradient echoes. In this report, we show how phosphorus and proton solid-state MRI yield the desired compositional information in bone specimens with ZTE and WASPI pulse sequences, respectively, coupled with the use of a two-port double-tuned solenoidal RF coil.</div><div>Electrical network simulations and construction details of the RF coil are detailed. Electrical performance was simulated using QUCS software to find the circuit component values that minimize reflected power and maximize interport isolation. Phantoms of known composition, as well as ex vivo femurs from normal, low bone density, and vitamin D-deficient rats, were included in the study. A simple correction for B₁ inhomogeneity was applied to achieve quantitative accuracy in the image intensity values.</div><div>Bone matrix and mineral densities derived from MRI strongly correlated (R² = 0.84) with chemical analysis, demonstrating the ability to measure compositional differences relevant to osteoporosis and osteomalacia.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107925"},"PeriodicalIF":2.0,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490632","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":"Circuit design for broadband decoupling in multi-coil multi-nuclear applications","authors":"Joseph Busher ,&nbsp;Edith Touchet-Valle ,&nbsp;Jacob Degitz ,&nbsp;Mary P. McDougall","doi":"10.1016/j.jmr.2025.107924","DOIUrl":"10.1016/j.jmr.2025.107924","url":null,"abstract":"<div><div>The wealth of information available from multinuclear magnetic resonance imaging and spectroscopy is largely untapped in the clinical setting. This is due to a multitude of challenges in the pipeline ranging from acquisition strategies, hardware design, processing, and interpretation/analysis. As a small part of addressing these challenges, this work presents a straightforward approach for broadband decoupling between coils. This circuit was created with the implementation of a series PIN diode and was evaluated on the bench and experimentally for ¹H, ³¹P and ²³Na at 3 T. Individual coils were single-tuned with this decoupling network and stacked to enable a switched triple-tuned coil. These coils were evaluated in various purposefully coupled configurations and compared to a narrowband trap active detuning network to demonstrate potential modularity of this design. Narrowband trapped coils showed drops in SNR when combined with other coils, presumably due to coupling between receiver elements tuned to different frequencies. This broadband decoupling behavior was shown to be independent of positioning through coils oriented to be nearly perfectly geometrically coupled and the addition of a three-element array of the same size. This configuration was validated on a post-mortem pig to verify the losses of the network did not prohibit its use for preclinical imaging and spectroscopy applications. Although losses were incurred as a result of the broadband decoupling network, it enabled a modular design that can be adapted to a given study without significant compromise of the signal integrity and could eliminate the need for certain custom coils for multi-nuclear studies.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"378 ","pages":"Article 107924"},"PeriodicalIF":2.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548630","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}