Journal of magnetic resonance最新文献

{"title":"Compact magnet design for magnetic resonance: A system-aware overview of optimization strategies, manufacturing technologies, and system-level trade-offs","authors":"Belal M.K. Alnajjar,&nbsp;Jens Anders","doi":"10.1016/j.jmr.2026.108164","DOIUrl":"10.1016/j.jmr.2026.108164","url":null,"abstract":"<div><div>Compact permanent-magnet systems are key enablers of portable and application-specific magnetic resonance (MR), but their design is inherently multi-objective: field strength and homogeneity must be balanced against size, weight, sample accessibility, manufacturability, thermal stability, and the requirements of the surrounding MR instrumentation. This article provides a system-aware overview of compact magnet design, linking established principles of magnet topology, magnetic materials, and shimming with emerging manufacturing technologies and numerical optimization strategies.</div><div>Open unilateral and closed magnet configurations are compared in terms of their field characteristics, accessibility, and suitability for different measurement tasks. Particular attention is given to passive and active shimming, including classical pole-piece and discrete-element approaches as well as free-form and additively manufactured correction structures. We further discuss how advanced manufacturing can expand the realizable geometric design space and thereby motivate optimization methods ranging from mixed-variable and population-based algorithms to free-form and data-driven approaches. At the same time, we emphasize that numerical optimization and additive manufacturing are not universally superior to established analytical design and conventional manufacturing; their value depends on the structure of the design problem and the practical constraints of its realization.</div><div>The magnet is treated as the central component of a coupled MR system rather than as an isolated field source. Interfaces to the rf transducer, shimming architecture, and supporting electronics are therefore considered where their requirements feed back into magnet-design decisions, particularly in portable and battery-powered instruments. This perspective also highlights an important limit of nominal geometric optimization: once material variability, manufacturing tolerances, and assembly errors dominate the residual field error, further optimization of the ideal magnet can yield diminishing practical returns and the design focus should shift toward a sufficiently capable and robust shim system.</div><div>By combining established magnet-design practice with recent developments in optimization and manufacturing, this overview aims to provide practical guidance for selecting design strategies according to the requirements, constraints, and production context of the intended MR application.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108164"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149120879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A compact portable MRI system for in-situ imaging and diffusion measurements","authors":"Mohammad Rasool Vaezi K.,&nbsp;Jan G. Korvink,&nbsp;Mazin Jouda","doi":"10.1016/j.jmr.2026.108175","DOIUrl":"10.1016/j.jmr.2026.108175","url":null,"abstract":"<div><div>Portable low-field magnetic resonance imaging (MRI) enables non-invasive measurements outside conventional laboratory environments, with emerging applications in plant science and environmental monitoring. In this work, we present a compact and modular MRI system optimized for portability and operation in constrained settings. The system integrates a 0.5<!--> <!-->T permanent magnet (1.25<!--> <!-->kg), an openable PCB-based RF coil for intact samples, planar gradient coils, and a miniaturized gradient driver. Its performance is validated through NMR spectroscopy, diffusion measurements, and MRI experiments. Diffusion coefficients of water and agar gel are successfully distinguished, and MRI imaging of structured phantoms achieves an in-plane resolution of <span><math><mrow><mn>93</mn><mo>×</mo><mn>93</mn><mspace></mspace><mi>μ</mi><msup><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>. Preliminary imaging of a living plant sample (Devil’s ivy) demonstrates the feasibility of non-invasive measurements on intact plant structures. The presented system provides a compact platform for portable MRI and represents a step toward future in-situ monitoring of water content and transport processes in small plant structures under natural environmental conditions.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108175"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149070887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron paramagnetic resonance spectra and electron spin relaxation of six-coordinate lanthanide complexes with a phosphine oxide ligand","authors":"Jacob P. Brannon,&nbsp;Thomas Albrecht,&nbsp;Sandra S. Eaton,&nbsp;Gareth R. Eaton","doi":"10.1016/j.jmr.2026.108179","DOIUrl":"10.1016/j.jmr.2026.108179","url":null,"abstract":"<div><div>X-band field-swept echo-detected spectra and electron spin relaxation times were measured for meridional pseudo-octahedral Ce³⁺, Nd³⁺, Sm³⁺, Gd³⁺, Tb³⁺, Er³⁺, Tm³⁺, and Yb³⁺ complexes with a phosphine oxide ligand (tris-(3,5-dimethoxyphenyl) phosphine oxide) (OPR₃) and compared with 8- and 9-coordinate complexes. Data for Tb³⁺, Er³⁺, and Tm³⁺ were also acquired at Q-band. T₁ and T_m values for the OPR₃ complexes, measured by 3-pulse inversion recovery and 2-pulse Hahn echo, are short relative to commonly observed values for 3d transition metal complexes or the same ions in 8- or 9-coordinate complexes. The short echo dephasing times are attributed to the effect of vibronic modulation of the large anisotropy of zero field splittings, g values, and hyperfine interactions on the echo refocusing. Other than the S-state Gd³⁺, the longest T₁ values for all of the coordination environments are for Tm³⁺. Although T₁ for Er³⁺ is the shortest for the aquo, HOPO, and LanM complexes, it is not the shortest for the OPR₃ complex, for which it is unusually temperature dependent. The shortest T₁ values for the OPR₃ complexes are for Sm³⁺ and Tb³⁺, which is attributed to very low-lying excited states, that vary with coordination environment. The microwave power required to create a π/2 pulse is in most cases consistent with J being a good quantum number, but for Tb³⁺ J + I gives better agreement. In some spectra the pulse power is the same over the magnetic field range of a few hundred G to 13,000 G, but in other cases different pulse powers are needed for different magnetic fields, which is attributed to multiple electronic energy levels.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108179"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149120874","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":"Supersonic spinning reveals second order effects in 1H spectra","authors":"Ats Kaldma,&nbsp;Mai-Liis Org,&nbsp;Kalju Vanatalu,&nbsp;Meelis Rohtmäe,&nbsp;Ago Samoson","doi":"10.1016/j.jmr.2026.108178","DOIUrl":"10.1016/j.jmr.2026.108178","url":null,"abstract":"<div><div><img>N<img>H vectors have long been important elements in protein studies. We show that coupling to spin <em>I</em> = 1 ¹⁴N can become a limiting factor for ¹H resolution even at the highest currently available magnetic fields.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108178"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149120900","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":"Suppressing t1-noise in solid-state NMR D-HMQC using spin-echo and dipolar-echo based sequences","authors":"Hao Gu,&nbsp;Yury G. Kolyagin,&nbsp;Julien Trébosc,&nbsp;Olivier Lafon,&nbsp;Jean-Paul Amoureux,&nbsp;Lixin Liang,&nbsp;Guangjin Hou","doi":"10.1016/j.jmr.2026.108176","DOIUrl":"10.1016/j.jmr.2026.108176","url":null,"abstract":"<div><div>The <em>D</em>-HMQC (dipolar-based heteronuclear multiple-quantum correlation) method has been extensively used in solid-state NMR for probing internuclear through-space correlations in materials, employing a dipolar recoupling sequence under MAS (magic angle spinning) conditions. However, the <em>D</em>-HMQC spectra often suffer from concomitant inevitable <em>t</em>₁-noise, which typically arises from the interferences of residual undesired interactions, e.g. CSA (chemical shift anisotropy) and MAS frequency fluctuations. Mitigating these interferences is essential for broader applications, especially at high magnetic fields. Herein, we propose two new methods to decrease these interferences: SE_CW-HMQC and DE-HMQC. The former incorporates two additional spin-echoes with the echo delays filled by CW decoupling, while the latter employs two dipolar-echoes. Through comprehensive simulations and experiments at slow-to-moderate MAS rates (≤ 25 kHz), we benchmark the performances of these two new methods against the recently reported TONE-HMQC and conventional <em>D</em>-HMQC sequences, where the wR4 (windowed R4) recoupling sequence is applied for achieving ¹H-{²⁷Al/⁷¹Ga}, ¹³C-{¹⁵N} and ¹⁹F-{¹³C} through-space correlations. These results show that the SE_CW-HMQC and TONE-HMQC sequences perform similarly in suppressing the CSA interference, while maintaining a high robustness to homonuclear dipolar couplings. However, among all these methods, DE-HMQC exhibits the highest tolerance to CSA and MAS instability, yielding the best-quality 2D correlation spectra with the lowest <em>t</em>₁-noise. For optimal performance under slow-to-moderate MAS rates, particularly in systems with strong homonuclear dipolar couplings, a wR4 recoupling sequence with a large window is highly recommended.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108176"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149083335","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":"Portable NMR for water studies in cultural heritage: from moisture quantitative mapping to non-invasive treatments evaluation","authors":"Noemi Proietti,&nbsp;Valeria Di Tullio","doi":"10.1016/j.jmr.2026.108174","DOIUrl":"10.1016/j.jmr.2026.108174","url":null,"abstract":"<div><div>Portable single-sided nuclear magnetic resonance (NMR) was applied to assess moisture distribution and treatment effects in cultural heritage materials using a stray-field NMR-MOUSE instrument. A quantitative, non-destructive methodology for moisture monitoring was developed based on calibrated ¹H NMR signal-amplitude mapping, enabling discrimination between superficial condensation, rising damp, and hygroscopic moisture retention. The approach was tested in two contrasting environments: the Catacombs of St. Callixtus (Rome) and the Oratory of St. Annunziata (Riofreddo). In addition, one-dimensional depth profiling was used to evaluate conservation interventions by measuring proton density and water relaxation properties as a function of depth. The method was applied to assess the effects of cleaning treatments on historic tempera-painted wooden panels and to characterize water transport in starch-based conservation materials. The results demonstrate the versatility of portable NMR as a robust, non-invasive analytical framework capable of translating raw NMR relaxometry data into actionable diagnostic metrics for preventative conservation strategies.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"391 ","pages":"Article 108174"},"PeriodicalIF":2.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149120825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hierarchical maximum likelihood estimation for time-resolved NMR data","authors":"Lennart H. Bosch ,&nbsp;Pernille R. Jensen ,&nbsp;Nico Striegler ,&nbsp;Thomas Unden ,&nbsp;Jochen Scharpf ,&nbsp;Usman Qureshi ,&nbsp;Philipp Neumann ,&nbsp;Martin Gierse ,&nbsp;John W. Blanchard ,&nbsp;Stephan Knecht ,&nbsp;Jochen Scheuer ,&nbsp;Ilai Schwartz ,&nbsp;Martin B. Plenio","doi":"10.1016/j.jmr.2026.108044","DOIUrl":"10.1016/j.jmr.2026.108044","url":null,"abstract":"<div><div>Metabolic monitoring and reaction rate estimation using hyperpolarized NMR technology requires accurate quantitative analysis of multidimensional data scenarios. Currently, this analysis is often performed in a two-stage procedure, which is prone to errors in uncertainty propagation and estimation. We propose an approach derived from a Bayesian hierarchical model that intrinsically propagates uncertainties and operates on the full data to maximize the precision at minimal uncertainty. In an analytic treatment, we reduce the estimation procedure to a least-squares optimization problem which can be understood as an extension of the Variable Projection (VarPro) approach for data scenarios with two predictors. We investigate the method’s efficacy in two experiments with hyperpolarized metabolites recorded with conventional high-field NMR devices and a micronscale NMR setup using Nitrogen-Vacancy centers in diamond for detection, respectively. In both examples, the new approach improves estimates compared to Fourier methods and proves operational advantages over a two-stage procedure employing VarPro. While the approach presented is motivated by NMR analysis, it is straightforwardly applicable to further estimation scenarios with similar data structure, such as time-resolved photospectroscopy.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"385 ","pages":"Article 108044"},"PeriodicalIF":1.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358017","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":"Feasibility of oxygen-enhanced MRI at 7T for assessing lung functional alterations in rats","authors":"Dmitrii B. Lebedev ,&nbsp;Mikhail V. Gulyaev ,&nbsp;Yury A. Pirogov","doi":"10.1016/j.jmr.2026.108031","DOIUrl":"10.1016/j.jmr.2026.108031","url":null,"abstract":"<div><div>Oxygen-enhanced (OE) magnetic resonance imaging (MRI) provides a non-invasive approach for assessing lung function. Its application in preclinical models is challenging due to rapid respiratory motion, the intrinsically short T₂* of lung tissue and susceptibility to magnetic field inhomogeneity. These limitations can be largely overcome using standard radial pulse sequences with ultra-short echo, combined with robust T₁-mapping techniques that include <em>B</em>₁⁺-field correction to ensure accurate quantification of regional oxygenation. In this study, we applied the Double Angle Method (DAM) to correct <em>B</em>₁⁺-field inhomogeneity for variable flip angle (VFA) T₁-mapping. Lung images were acquired using a 3D ultrashort echo time (UTE) sequence, enabling assessment of regional T₁ values during ambient air and 95% O₂ inhalation. Both healthy control rats and animals with acute lung inflammation induced by intratracheal lipopolysaccharide (LPS) were studied. Baseline T₁ values in the lung parenchyma were higher in LPS-treated animals compared to controls, with visually identified inflamed regions showing the greatest elevation. Upon inhalation of 95% O₂, T₁ decreased in all groups, but the relative reduction was smaller in LPS-treated lungs than in controls and minimal in inflamed regions, indicating impaired regional oxygen responsiveness. These results demonstrate the feasibility of OE MRI for detecting localized functional impairments in the lungs caused by inflammation.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"385 ","pages":"Article 108031"},"PeriodicalIF":1.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146215157","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":"Characterization of shale using T2–T2∗ relaxation correlation measurements","authors":"Dominic O. Couillard,&nbsp;Mohammad Sadegh Zamiri,&nbsp;Bruce J. Balcom,&nbsp;Benedict Newling","doi":"10.1016/j.jmr.2026.108033","DOIUrl":"10.1016/j.jmr.2026.108033","url":null,"abstract":"<div><div>Magnetic resonance 2D relaxation correlation measurements have been shown to be an incredibly effective way of characterizing complex porous media. Such porous media systems are important for various industries, including the energy industry. Organic shale is a prevalent example in the energy industry. In this paper, we demonstrate the characterization of a shale sample using our new <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>-<span><math><msubsup><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span> correlation measurement. We show that the measurement is capable of distinguishing between different hydrogen environments in shale, demonstrating analytical potential for composite porous media. We also show that <span><math><msubsup><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span> cannot always be used as an analogue to <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> in heterogeneous media, as shown by peak migrations away from contours of constant <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>/<span><math><msubsup><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span>, caused by changing the magnetic field strength.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"385 ","pages":"Article 108033"},"PeriodicalIF":1.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147313712","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":"Unmatched delay line NMR probes for magnetic resonance","authors":"Nathan Evetts","doi":"10.1016/j.jmr.2026.108032","DOIUrl":"10.1016/j.jmr.2026.108032","url":null,"abstract":"<div><div>In magnetic resonance experiments the delay line probe is useful for its broadband impedance match and short ring down times. However, it is usually difficult to construct, and less sensitive than resonant probes. Additionally, the delay line has been widely misused in a manner that further degrades its performance due to an interference effect. We report that significant improvements in signal-to-noise ratio (<span><math><mo>∼</mo></math></span>2x) are available when the probe is used with an unmatched termination. This improvement is experimentally demonstrated using both an <span><math><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup></math></span>H NMR signal in a variable electromagnet and with typical “sniffer” coil measurements that characterize <span><math><msub><mrow><mi>B</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. A quantitative comparison is made with both resonant and bare-coil (“no-tune-no-match”) probes. A novel “echo” type signal is observed in the delay line free induction decay under certain conditions. To alleviate the difficulty of construction we describe an approach using printed circuit board fabrication methods. A PCB delay line probe operating from 4–400 MHz is realized for a magnetometry application. The probe is observed to be robust in cryogenic environments. Finally, we show how to better characterize and optimize a delay line style probe with ordinary vector network analyzer measurements. These practical details are missing from the literature, and relevant to several branches of physics in which broadband spin control is an important technique.</div></div>","PeriodicalId":16267,"journal":{"name":"Journal of magnetic resonance","volume":"385 ","pages":"Article 108032"},"PeriodicalIF":1.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146260511","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}