Magnetic Resonance Letters最新文献

{"title":"Protamine-1 encoded recombinant adeno-associated virus for enhanced brain magnetic resonance imaging","authors":"Kairu Xie ,&nbsp;Yaping Yuan ,&nbsp;Mou Jiang ,&nbsp;Daiqin Chen ,&nbsp;Shizhen Chen ,&nbsp;Xin Zhou","doi":"10.1016/j.mrl.2025.200222","DOIUrl":"10.1016/j.mrl.2025.200222","url":null,"abstract":"<div><div>Magnetic resonance imaging (MRI) is a powerful tool for diagnosing and monitoring brain diseases, but its low sensitivity can hinder early detection. To address this challenge, we utilized chemical exchange saturation transfer (CEST) MRI, which greatly enhances sensitivity for detecting low-concentration compounds. In this study, we developed a CEST contrast agent based on a recombinant adeno-associated viruses (rAAVs) encoding the protamine-1 (PRM1) MRI reporter gene. CEST MRI revealed that PRM1 contrast agent effectively highlighted caudate putamen region after injection of the rAAVs into the mouse brain, clearly distinguishing it from the surrounding tissue, with no observable damage. This method provides a sensitive, metal-free CEST contrast agent for <em>in vivo</em> brain cell detection, demonstrating potential for both diagnostic and therapeutic applications in brain diseases.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200222"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast acquisition of high resolution liquid NMR spectroscopy","authors":"Wen Zhu,&nbsp;Mengjie Qiu,&nbsp;Yao Luo,&nbsp;Xiaoqi Shi,&nbsp;Zhong Chen,&nbsp;Yanqin Lin","doi":"10.1016/j.mrl.2025.200224","DOIUrl":"10.1016/j.mrl.2025.200224","url":null,"abstract":"<div><div>Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for analyzing molecular structure and composition. However, traditional NMR experiments suffer from long acquisition times, especially in multidimensional NMR spectroscopy. This problem, to some extent, limits broader applications of NMR techniques. Various methods have been proposed to accelerate sampling, including non-uniform sampling (NUS), multi-FID acquisition (MFA), Hadamard encoding, Fourier encoding, spatial encoding Ultrafast 2D NMR (UF2DNMR), and so on. The review focuses on rapid sampling methods developed in contemporary China, introducing their fundamental principles and applications while discussing their respective advantages and disadvantages.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200224"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"OFC: Outside Front Cover","authors":"","doi":"10.1016/S2772-5162(26)00005-7","DOIUrl":"10.1016/S2772-5162(26)00005-7","url":null,"abstract":"","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200261"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147414114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-supervised pre-training based hybrid network for deep gray matter nuclei segmentation","authors":"Yang Deng ,&nbsp;Jiaxiu Xi ,&nbsp;Zhong Chen ,&nbsp;Lijun Bao","doi":"10.1016/j.mrl.2025.200226","DOIUrl":"10.1016/j.mrl.2025.200226","url":null,"abstract":"<div><div>The accurate segmentation of deep gray matter nuclei is critical for neuropathological research, disease diagnosis and treatment. Existing methods employ the supervised learning training approach, which requires large labeled datasets. It is challenging and time-consuming to obtain such datasets for medical image analysis. In addition, these methods based on convolutional neural networks (CNNs) only achieve suboptimal performance due to the locality of convolutional operations. Vision Transformers (ViTs) efficiently model long-range dependencies and thus have the potentiality to outperform these methods in segmentation tasks. To address these issues, we propose a novel hybrid network based on self-supervised pre-training for deep gray matter nuclei segmentation. Specifically, we present a CNN-Transformer hybrid network (CTNet), whose encoder consists of 3D CNN and ViT to learn local spatial-detailed features and global semantic information. A self-supervised learning (SSL) approach that integrates rotation prediction and masked feature reconstruction is proposed to pre-train the CTNet, enabling the model to learn valuable visual representations from unlabeled data. We evaluate the effectiveness of our method on 3T and 7T human brain MRI datasets. The results demonstrate that our CTNet achieves better performance than other comparison models and our pre-training strategy outperforms other advanced self-supervised methods. When the training set has only one sample, our pre-trained CTNet enhances segmentation performance, showing an 8.4% improvement in Dice similarity coefficient (DSC) compared to the randomly initialized CTNet.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200226"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature dependence of two or more water species in delignified wood and lignocellulosic, tracked by LFNMR relaxometry","authors":"Long Zhou ,&nbsp;Wenjing Liu ,&nbsp;Zhihong Zhao ,&nbsp;Rui Tan ,&nbsp;Xiaofeng Zhu ,&nbsp;Shen Wang ,&nbsp;Zonghai Harry Xie ,&nbsp;Minghui Zhang","doi":"10.1016/j.mrl.2025.200221","DOIUrl":"10.1016/j.mrl.2025.200221","url":null,"abstract":"<div><div>Distributions of nuclear magnetic resonance (NMR) relaxation times provide detailed information about the water in wood. This study documents the water dynamics analysis of <em>T</em>₂ and <em>T</em>₁ distributions for saturated delignified sapwood (DSW), delignified heartwood (DHW) and lignocellulose (LC) samples at different temperatures. Results indicate that below the freezing point of bulk water, free water freezes, causing its signal to disappear from the distribution. Then, the low temperature distributions of the unfrozen bound water contain more information about its components, with DSW, DHW and LC containing two distinct states of bound water (OH bound water (B-water) and more freely bound water (C-water)). Furthermore, it was observed that within the temperature range of −3°C to −60°C, B-water in DSW, DHW and LC maintained a higher unfrozen water content (UWC) value than C-water, and the <em>T</em>₁/<em>T</em>₂ ratios for B-water were consistently higher than that for C-water, indicating that B-water has a greater antifreeze capacity. <em>T</em>₂ and <em>T</em>₁ distributions offer different kinds of information about water components, and all peaks within the distribution have been assigned.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200221"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of the interaction between human cytochrome c and transfer RNAphe","authors":"Guangqing Zhang ,&nbsp;Jianhua Zhan ,&nbsp;Xin Chai ,&nbsp;Bin Jiang ,&nbsp;Maili Liu ,&nbsp;Xu Zhang ,&nbsp;Danyun Zeng","doi":"10.1016/j.mrl.2025.200219","DOIUrl":"10.1016/j.mrl.2025.200219","url":null,"abstract":"<div><div>Cytochrome <em>c</em> (cyt <em>c</em>) is released from mitochondria into the cytosol upon apoptotic stimulation, ultimately triggering programmed cell death. Recent studies have revealed that transfer RNA (tRNA) interacts with cyt <em>c</em>, impeding the formation of the apoptosome complex and thereby suppressing apoptosis. To elucidate the molecular mechanism underlying the interaction between cyt <em>c</em> and tRNA, nuclear magnetic resonance (NMR)-based chemical shift perturbation and intensity analysis were employed to characterize the binding interface between cyt <em>c</em> and tRNA^phe. The findings demonstrate that cyt <em>c</em> primarily engages with tRNA^phe through its 70–85 Ω-loop and <em>N</em>-terminal α-helix. This interaction sterically hinders the accessibility of small molecules, such as H₂O₂, to the hydrophobic pocket of cyt <em>c</em>, consequently attenuating its peroxidase activity. Furthermore, oxidative modification of cyt <em>c</em>, particularly the carbonylation of positively charged lysine residues, weakens this interaction.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200219"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the effect of ethanol-water structuring on the transport properties of ethanol in porous silicas","authors":"Jordan Ward-Williams ,&nbsp;Andrew Sederman ,&nbsp;Michael Mantle ,&nbsp;Matthias Appel ,&nbsp;Lynn Gladden","doi":"10.1016/j.mrl.2025.200227","DOIUrl":"10.1016/j.mrl.2025.200227","url":null,"abstract":"<div><div>The transport properties of liquid mixtures confined within porous media can change significantly from those observed for bulk mixtures due to changes in the liquid structuring within the pore space. Here, pulsed field gradient NMR was used to measure the diffusion coefficient of ethanol in ethanol-water liquid mixtures confined within silicas with pore diameters of 6 nm and 3 nm as a function of composition. For liquids imbibed within the 6 nm pores, the composition dependence of the ethanol diffusion coefficient closely followed that of the bulk liquid mixture and the absolute diffusion coefficients were reduced by a tortuosity factor of 3, with a minor contribution due to liquid-surface interactions. For liquids imbibed within the 3 nm pores, the diffusion coefficient of ethanol decreased as the composition of ethanol within the pore space increased, and for single-component ethanol imbibition the effective tortuosity was 63. Fast field cycling NMR experiments showed that the diffusion behaviour was not controlled by an increase in ethanol adsorption strength. A geometric analysis of the pore space was consistent with a highly confined system in which most molecules interacted with the pore walls. Under such confinement, the liquid structuring within the bulk pore space did not reflect that of the bulk liquid mixtures, and the observed decrease in diffusion coefficient as ethanol composition increased was consistent with an increase in confinement due to the larger size of the ethanol molecule.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200227"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SNMR with short pulses: Optimizing the kernel calculation by considering the influence of pulse shape and phase","authors":"Tobias Splith ,&nbsp;Thomas Hiller ,&nbsp;Stephan Costabel ,&nbsp;Mike Müller-Petke","doi":"10.1016/j.mrl.2025.200223","DOIUrl":"10.1016/j.mrl.2025.200223","url":null,"abstract":"<div><div>In the past few years, efforts have been made to extend the sensitivity of surface nuclear magnetic resonance (SNMR) to short relaxation times, typical for strongly bound water, which, for example, occurs in partially saturated soils. The two limiting factors for the sensitivity are the dead time after the excitation pulse and the duration of the pulse itself. To enable short pulses, while also achieving proper depths of investigation, high pulse amplitudes are needed. This makes it necessary to consider the Bloch-Siegert effect, i.e. the counter-rotating component and the parallel component of the excitation field have significant influence on the excitation. If an untuned transmitter circuit is used, the pulse shape will also be non-sinusoidal. In this paper, we demonstrate that this influences SNMR measurements with short pulses in two ways: On one hand, the pulse shape influences the phase of the fundamental frequency oscillation. On the other, at very high pulse amplitudes, other frequency components of the excitation field start to influence the excitation. The behavior of the macroscopic magnetizations in the subsurface during the pulse is simulated by solving the Bloch equations, using the pulse shape as an input. Since these calculations are computational expensive, we propose a lookup scheme that allows a time efficient modeling of the obtained SNMR data.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 1","pages":"Article 200223"},"PeriodicalIF":1.7,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147367535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validity of the Gaussian phase distribution approximation for analysis of isotropic diffusion encoding applied to restricted diffusion in a cylinder","authors":"Daniel Topgaard","doi":"10.1016/j.mrl.2025.200196","DOIUrl":"10.1016/j.mrl.2025.200196","url":null,"abstract":"<div><div>The Gaussian phase distribution approximation enables analysis of restricted diffusion encoded by general gradient waveforms but fails to account for the diffraction-like features that may occur for simple pore geometries. We investigate the range of validity of the approximation by random walk simulations of restricted diffusion in a cylinder using isotropic diffusion encoding sequences as well as conventional single gradient pulse pairs and oscillating gradient waveforms. The results show that clear deviations from the approximation may be observed at relative signal attenuations below 0.1 for one-dimensional sequences with few oscillation periods. Increasing the encoding dimensionality and/or number of oscillations while extending the total duration of the waveform diminishes the non-Gaussian effects while preserving the low apparent diffusivities characteristic of restriction.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"5 4","pages":"Article 200196"},"PeriodicalIF":1.7,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid and quantitative 1D 13C NMR analysis of polypropylene tacticity with relaxation agent and proton polarization transfer","authors":"Xuelei Duan ,&nbsp;Peiqian Yu ,&nbsp;Yue Yu ,&nbsp;Linge Ma ,&nbsp;Youlin Xia ,&nbsp;Aitor Moreno ,&nbsp;Linfeng Chen ,&nbsp;Rongjuan Cong ,&nbsp;Congyun Liu ,&nbsp;Zhe Zhou","doi":"10.1016/j.mrl.2025.200198","DOIUrl":"10.1016/j.mrl.2025.200198","url":null,"abstract":"<div><div>Polypropylene (PP) accounts for approximately 28.0% of the global polyolefin market, valued at $243.4 billion in 2022. Known for its lightweight, chemical resistance, cost-effectiveness, high strength and melting point, PP is widely used in various applications. Its properties and applications are closely tied to its tacticity. One-dimensional (1D) conventional ¹³C NMR has been extensively utilized to analyze PP tacticity, but its low sensitivity and longer relaxation time remain drawbacks. Typically, analyzing a single PP sample requires around 9 h of NMR time. Using of a cryogenically cooled 10 mm NMR probe can significantly reduce this measurement time; however, its high cost makes it inaccessible for most NMR laboratories. While the refocused insensitive nuclei enhanced by polarization transfer (RINEPT) technique is well-known for enhancing NMR sensitivity, there are no published studies using 1D ¹³C RINEPT to quantify PP tacticity. Relaxation agents like chromium (III) acetylacetonate (Cr(acac)₃) have also been used to reduce relaxation times in polyolefin NMR analyses. Here we introduce a straightforward and easily implementable 1D ¹³C NMR method for rapid PP tacticity quantification. This method combines Cr(acac)₃, Bruker's existing RINEPT pulse sequence (ineptrd), and our recently published ¹H decoupling sequence (bi_waltz65_256 pl) to eliminate ¹H decoupling artifacts. It is worth noting that decoupling artifacts are always present. When the signal-to-noise ratio (SNR) is low, these artifacts are obscured by noise. For example, in some two-dimensional (2D) or three-dimensional (3D) NMR spectra, decoupling artifacts are barely visible because of the low SNR. However, when attempting to observe weak signals in 1D spectra, increasing the sample concentration or the number of scans enhances the SNR, revealing the decoupling artifacts. The decoupling artifacts appeared superimpose with some other weak signals, affecting the measurements of signal intensities. Therefore, improved ¹H-decoupling methods are crucial for such data acquisition. This synergy results in a 9.4- to 9.7-fold sensitivity enhancement, equating to an 88- to 94-fold reduction (9.4² ≈ 88, 9.7² ≈ 94) in NMR acquisition time compared to conventional 1D ¹³C NMR experiment with Cr(acac)₃. The time savings are even more substantial compared to experiments without Cr(acac)₃. The faster and quantitative approach is accessible to researchers with or without cryoprobes. Beyond PP, this method can be applied to tacticity measurements of other polyolefins, such as polybutene, polyhexene and polyoctene.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"5 4","pages":"Article 200198"},"PeriodicalIF":1.7,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}