Magnetic Resonance Letters最新文献_第2页

Truncated enhanced constraint for low-rank plus sparse in cardiac dynamic MRI reconstruction 心脏动态MRI重建中低秩加稀疏的截断增强约束

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-09-11 DOI: 10.1016/j.mrl.2025.200241

Runyu Yang, Haozhong Sun, Xiaoqi Lin, Haokun Li, Huijun Chen

{"title":"Truncated enhanced constraint for low-rank plus sparse in cardiac dynamic MRI reconstruction","authors":"Runyu Yang, Haozhong Sun, Xiaoqi Lin, Haokun Li, Huijun Chen","doi":"10.1016/j.mrl.2025.200241","DOIUrl":"10.1016/j.mrl.2025.200241","url":null,"abstract":"<div><div>Cardiac dynamic MRI has been widely used in cine and perfusion imaging, in which low-rank and sparse priors play an important role in reconstructing dynamic images with high temporal and spatial resolution from undersampled acquisition. However, the accuracy of singular value estimation may greatly affect the precision of low-rank regularization, resulting in suboptimal reconstruction. A novel reconstruction method employing truncated enhanced constraint for low-rank plus sparse method in cardiac dynamic MRI reconstruction (TRIONES) was proposed to accurately estimate the rank function for dynamic MRI (dMRI) reconstruction. TRIONES uses truncated nuclear norm to assign different shrink values to different singular vectors, preserving the essential image information while effectively eliminating noise. The proposed method was validated in simulation and <em>in vivo</em> experiments for myocardial cine and perfusion MRI reconstruction, comparing with widely used reconstruction methods. The proposed method achieved higher peak signal-to-noise ratio (PSNR), structural similarity (SSIM), and smaller normalized root mean squared error (NRMSE) compared to widely used reconstruction methods in the simulation and <em>in vivo</em> cardiac dynamic MR datasets, suggesting its advantage of accurate rank estimation in cardiac dynamic MRI reconstruction. The proposed TRIONES method can improve low-rank based reconstruction methods for dynamic MRI. It provided more accurate and efficient image information, benefiting the clinical application of heart-related diseases.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200241"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011553","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}

引用次数: 0

A random fractional 13C labeling strategy for P. pastoris expressed eukaryotic membrane proteins for solid-state NMR studies 一种用于固态核磁共振研究的表达真核膜蛋白的随机分数13C标记策略

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-11-03 DOI: 10.1016/j.mrl.2025.200253

Meihui Sang , Zejun Fan , Qiongqiong Ren , Jing Liu , Shaokai Zhao , Shenlin Wang

{"title":"A random fractional 13C labeling strategy for P. pastoris expressed eukaryotic membrane proteins for solid-state NMR studies","authors":"Meihui Sang , Zejun Fan , Qiongqiong Ren , Jing Liu , Shaokai Zhao , Shenlin Wang","doi":"10.1016/j.mrl.2025.200253","DOIUrl":"10.1016/j.mrl.2025.200253","url":null,"abstract":"<div><div>Solid-state NMR (SSNMR) has emerged as an important technique for characterizing membrane protein structures. Using sparse <sup>13</sup>C labeling of membrane proteins can significantly enhance spectral resolution. In this study, we present an investigation of a random fractional <sup>13</sup>C labeling approach for large eukaryotic membrane proteins produced in <em>P. pastoris</em> for SSNMR research. This method takes advantage of the fact that <em>P. pastoris</em> can use the C1 compound methanol as the sole carbon source. Thus, incorporating a mixture of natural abundance (NA) methanol and <sup>13</sup>C-methanol in the expression medium enables random fractional <sup>13</sup>C labeling of the expressed proteins. The labeling strategy was assessed using a eukaryotic rhodopsin from <em>Leptosphaeria maculans</em> (LR). A comparison of 1D-<sup>13</sup>C and 2D<sup>15</sup>N–<sup>13</sup>C spectra of LR expressed in media with different ratios of <sup>13</sup>C-methanol to NA-methanol revealed a notable decrease in the <sup>13</sup>C linewidth of LR as the proportion of <sup>13</sup>C-methanol decreased. A<sup>13</sup>C enrichment level of 25% was determined for balance between spectral resolution and sensitivity, resulting in an average <sup>13</sup>C line-width for LR that is half of uniform <sup>13</sup>C labeling. This reduction in linewidths led to a 50% increase in the number of well-resolved cross-peaks on <sup>15</sup>N-<sup>13</sup>Cα spectra. The random fractional <sup>13</sup>C labeling method only uses economic <sup>13</sup>C-labeled methanol, providing a cost-effective approach for sparse <sup>13</sup>C labeling to improve the SSNMR spectral resolution of membrane proteins. It will be beneficial to site-specific characterization on membrane protein structure, dynamics and interactions.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200253"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011408","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}

引用次数: 0

Structural anisotropy in celery stalks by microscopic MRI and polarized light microscopy 显微MRI和偏振光显微镜观察芹菜茎结构的各向异性

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-10-23 DOI: 10.1016/j.mrl.2025.200250

Sarah Salem , Farid Badar , Amanveer Singh , Vladimir Sokolovsky , Gregory Furman , Yang Xia

{"title":"Structural anisotropy in celery stalks by microscopic MRI and polarized light microscopy","authors":"Sarah Salem , Farid Badar , Amanveer Singh , Vladimir Sokolovsky , Gregory Furman , Yang Xia","doi":"10.1016/j.mrl.2025.200250","DOIUrl":"10.1016/j.mrl.2025.200250","url":null,"abstract":"<div><div>Structural anisotropy of celery stalks was studied using <em>T</em><sub>2</sub> anisotropy in microscopic MRI (μMRI) and supplemented by quantitative polarized light microscopy (PLM) at optical resolutions. Parenchyma, which is the ground tissue in celery and has a diameter in the range of 50–90 μm, was found to have isotropic <em>T</em><sub>2</sub>; in contrast, collenchyma, which is the structural part of the ground tissue in celery and has a diameter in the range of 8–12 μm, was found to have strong anisotropic <em>T</em><sub>2</sub>. Substantial size variations within each porous structure and substantial co-existences of more than one type of structural tissues within a single μMRI voxel were noticed in the optical images, which can contribute to the less clear anisotropies in the smaller vascular structures (e.g., phloem (approximately 2–6 μm in diameter) and xylem (approximately 5–15 μm in diameter)). Celery could be used as a simple plant model to study the relationships between tissue microstructures and nuclear spin relaxation in fibrous and porous specimens.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200250"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011409","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}

引用次数: 0

Spin-echo measurements for capillary rheometry at low field 低场毛细管流变测量的自旋回波测量

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-07-29 DOI: 10.1016/j.mrl.2025.200229

Sebastian Richard, Bruce J. Balcom, Benedict Newling

{"title":"Spin-echo measurements for capillary rheometry at low field","authors":"Sebastian Richard, Bruce J. Balcom, Benedict Newling","doi":"10.1016/j.mrl.2025.200229","DOIUrl":"10.1016/j.mrl.2025.200229","url":null,"abstract":"<div><div>A single spin-echo, acquired in the presence of a constant magnetic field gradient, has a phase proportional to the average velocity of the sample and an amplitude determined by the distribution of velocities for laminar flow in a pipe. If we make assumptions about symmetry, it is therefore possible to reconstruct a velocity profile from a series of spin echoes acquired with different echo times, <span><math><mrow><mtext>TE</mtext><mo>=</mo><mn>2</mn><mi>τ</mi></mrow></math></span>. The velocity profile encompasses a range of shear stresses and so describes the shear-rate dependence of the fluid viscosity, making this a rapid, non-invasive rheometric measurement. The appeal of this approach lies in its simplicity: a constant, uniform magnetic field gradient can be readily constructed using low-field permanent magnets and the resulting magnetic resonance instrument is relatively cheap and easily sited. In order to extend the range of fluids to which such a rheometer can be applied, we have designed a pre-measurement polarization unit to maximize the polarization of fluids with a long <span><math><mrow><msub><mi>T</mi><mn>1</mn></msub></mrow></math></span>, such as aqueous solutions.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200229"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011550","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}

引用次数: 0

Single-scan ultra-selective probing on targeted components from overlapped NMR spectra 从重叠核磁共振光谱中对目标组分进行单扫描超选择性探测

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-09-11 DOI: 10.1016/j.mrl.2025.200242

Haolin Zhan , Liangliang Hu , Yuqing Huang , Zhong Chen

{"title":"Single-scan ultra-selective probing on targeted components from overlapped NMR spectra","authors":"Haolin Zhan , Liangliang Hu , Yuqing Huang , Zhong Chen","doi":"10.1016/j.mrl.2025.200242","DOIUrl":"10.1016/j.mrl.2025.200242","url":null,"abstract":"<div><div>Benefitting from the non-invasive and quantitative detection property, liquid NMR spectroscopy shows broad applications in the identification, separation, and structural determination of chemical substances in mixtures. However, its applications, especially to probing complex mixtures that contain abundant components and complicated molecular structures, somewhat encounter the challenge of spectral congestion. In this study, we demonstrate the ultra-selective extraction of targeted components from overlapped NMR spectra for mixture analyses by investigating the applications of the recent 1D selective GEMSTONE-TOCSY approach. This strategy first adopts an ultra-selective chemical shift filter to choose the targeted spins related to the components of interest, even though situated at overlapped spectral regions with decent suppression on unwanted surrounding signals. Sequentially, it utilizes the 1D selective TOCSY scheme to accurately extract total coupling networks associated with targeted spins, and then spectroscopically separate individual components, thus resolving overlapped NMR spectra. Apart from the measurements on electrolyte and sugar mixtures, experimental results demonstrate that it also allows one to analyze heterogeneous biological tissues containing plentiful metabolites and intrinsic field inhomogeneity <em>via</em> specific probe access to targeted components. Therefore, this study demonstrates a useful tool for component analyses and molecular structure measurements on complex chemical and biological mixtures, and it shows promising prospects for wide applications in the fields of chemistry, biology, energy, etc.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200242"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011548","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}

引用次数: 0

Mean pore diameters of 3D printed micro-capillaries using the matrix pencil method 使用矩阵铅笔法3D打印微血管的平均孔径

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-05-01 Epub Date: 2025-08-08 DOI: 10.1016/j.mrl.2025.200239

Dennis Wörtge , Jan Claussen , Behzad Mohebbi , Siegfried Stapf , Bernhard Blümich , Matthew Augustine

{"title":"Mean pore diameters of 3D printed micro-capillaries using the matrix pencil method","authors":"Dennis Wörtge , Jan Claussen , Behzad Mohebbi , Siegfried Stapf , Bernhard Blümich , Matthew Augustine","doi":"10.1016/j.mrl.2025.200239","DOIUrl":"10.1016/j.mrl.2025.200239","url":null,"abstract":"<div><div>The matrix pencil method (MPM) is an approach for quantitative analysis of the multi-exponential time-domain signals from relaxation and diffusion NMR experiments. In contrast to other signal processing methods, MPM relies on solving the generalized eigenvalue problem of a so-called matrix pencil, resulting in discrete values representing the different relaxation species. In this work, the methodology is extended from relaxation experiments towards assessment of NMR self-diffusion studies in micro-porous media on a length scale suitable for determining pore sizes from signal decays. For this, well-defined 3D nano printed micro-capillary structures are introduced as model porous media to correlate the apparent diffusion coefficients derived by MPM from pulsed gradient spin echo (PGSE) experiments to the pore diameter reported by the root-mean-square displacement (RMSD) of molecules diffusing in an array of many regular pores. Due to the high uniformity of the capillaries, the observed signal decay curves are modulated by diffusive diffraction. This phenomenon occurs when the paths of the diffusing spins are confined in an ensemble of identical pores, leading to repeated refocusing of phase coherence in <em>q</em> space. From the <em>q</em> values of the minima, the pore size can be determined for known pore shapes. This can be used as ground truth to validate the results from diffusometry experiments calculated by quantitative analysis methods such as MPM. Results show that MPM algorithm effectively quantifies the diameter within a restricted diffusion experiment. In addition, MPM separates two diffusion components and predicts the correct pore sizes as well as the respective relative contributions.</div></div>","PeriodicalId":93594,"journal":{"name":"Magnetic Resonance Letters","volume":"6 2","pages":"Article 200239"},"PeriodicalIF":1.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148011551","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}

引用次数: 0

Protamine-1 encoded recombinant adeno-associated virus for enhanced brain magnetic resonance imaging 蛋白蛋白1编码重组腺相关病毒用于增强脑磁共振成像。

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-02-01 Epub Date: 2025-06-18 DOI: 10.1016/j.mrl.2025.200222

Kairu Xie , Yaping Yuan , Mou Jiang , Daiqin Chen , Shizhen Chen , Xin Zhou

引用次数: 0

Fast acquisition of high resolution liquid NMR spectroscopy 快速采集高分辨率液体核磁共振波谱。

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-02-01 Epub Date: 2025-06-30 DOI: 10.1016/j.mrl.2025.200224

Wen Zhu, Mengjie Qiu, Yao Luo, Xiaoqi Shi, Zhong Chen, Yanqin Lin

引用次数: 0

OFC: Outside Front Cover OFC：外封面

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-02-01 Epub Date: 2026-02-27 DOI: 10.1016/S2772-5162(26)00005-7

引用次数: 0

Self-supervised pre-training based hybrid network for deep gray matter nuclei segmentation 基于自监督预训练的混合网络深度灰质核分割。

IF 1.7

Magnetic Resonance Letters Pub Date : 2026-02-01 Epub Date: 2025-07-12 DOI: 10.1016/j.mrl.2025.200226

Yang Deng , Jiaxiu Xi , Zhong Chen , Lijun Bao

{"title":"Self-supervised pre-training based hybrid network for deep gray matter nuclei segmentation","authors":"Yang Deng , Jiaxiu Xi , Zhong Chen , 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}

引用次数: 0