Magnetic Resonance in Medicine最新文献

{"title":"Modelling Motion-Induced Signal Corruption in Steady-State Diffusion MRI.","authors":"Benjamin C Tendler, Wenchuan Wu, Karla L Miller, Aaron T Hess","doi":"10.1002/mrm.70315","DOIUrl":"10.1002/mrm.70315","url":null,"abstract":"<p><strong>Purpose: </strong>Diffusion-weighted steady-state free precession (DW-SSFP) is a diffusion imaging sequence achieving high SNR efficiency. A key challenge for in vivo DW-SSFP is the sequence's severe motion sensitivity, currently limiting investigations to low or no motion regimes. Here we establish a framework to both (1) model and (2) correct for the impact of subject motion associated with the underlying magnetisation distribution of DW-SSFP.</p><p><strong>Theory and methods: </strong>An extended phase graphs (EPG) representation of the 1D DW-SSFP signal was established incorporating a motion operator describing rigid body and pulsatile motion. The representation was validated using Monte Carlo simulations, and subsequently integrated into a data fitting routine for motion estimation and correction. The fitting routine was evaluated using both simulations and a voxelwise correction applied to in vivo experimental 2D low-resolution single-shot timeseries DW-SSFP data acquired in the human brain in three healthy volunteers, with a tensor reconstructed from the motion-corrected experimental DW-SSFP data.</p><p><strong>Results: </strong>The proposed EPG-motion framework gives excellent agreement to complementary Monte Carlo simulations, demonstrating that diffusion coefficient estimation is robust over a range of motion and SNR regimes. Tensor estimates from the motion-corrected experimental DW-SSFP data give good visual agreement to complementary diffusion-weighted spin-echo (DW-SE) data acquired in the same subject, considerably reducing orientation-dependent motion-induced biases.</p><p><strong>Conclusion: </strong>Temporal information capturing the evolution of the DW-SSFP signal can be used to retrospectively (1) estimate subject motion and (2) reconstruct motion-corrected DW-SSFP data. Open-source software is provided, facilitating future investigations into the impact of subject-motion on DW-SSFP acquisitions.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"66-82"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147317465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Free-Breathing Magnetization Transfer Imaging of the Lung at 0.55 T Using bSTAR.","authors":"Alexandra Braun, Grzegorz Bauman, Maurice Pradella, Jonathan Röcken, Katrin E Hostettler, Oliver Bieri","doi":"10.1002/mrm.70341","DOIUrl":"10.1002/mrm.70341","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a clinically applicable method for magnetization transfer (MT) imaging of the lung at 0.55 T.</p><p><strong>Methods: </strong>MT imaging of the chest was explored in healthy volunteers at 0.55 T using a self-gated 3D half-radial dual-echo balanced steady-state free precession sequence (bSTAR), a 2D multi-slice gradient echo method (GRE) acquired in end-expiratory breath-hold, and a self-gated 3D half-radial single-echo ultra-short TE (UTE) approach. MT contrast relied on RF pulse prolongation for bSTAR and on pulsed off-resonance irradiation for UTE and GRE. Data reconstruction from the self-gated scans was performed offline and for the end-expiratory tidal phase using a compressed sensing algorithm. MT ratio (MTR) maps were derived from an MT-weighted and a non-MT-weighted scan and took 8:32 min for bSTAR, 17:16 min for UTE, and 0:48 min for GRE. In addition, patients with pulmonary diseases underwent bSTAR MTR imaging.</p><p><strong>Results: </strong>MT imaging was successfully performed in all volunteers with highly similar average MTR values for the lung of 28.8 pu (UTE), 29.4 pu (GRE), and 30.7 pu (bSTAR). In terms of resolution, however, bSTAR clearly outperformed both UTE and GRE variants. Finally, MTR imaging with bSTAR demonstrated high reproducibility in volunteers and showed substantially different MTR values for patients with various pulmonary diseases.</p><p><strong>Conclusion: </strong>At 0.55 T, MT-sensitized bSTAR offers in vivo high-resolution free-breathing MTR imaging of the entire lung in clinically acceptable scan times and shows high reproducibility. Initial results suggest that MTR imaging at 0.55 T may potentially serve as a noninvasive biomarker for investigating and differentiating pulmonary diseases.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"203-213"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147444272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Free-Running Simultaneous Imaging of the Entire Lung and Heart With Isotropic Resolution.","authors":"Zekang Ding, Sifan Wu, Huajun She, Li Fan, Yiping P Du","doi":"10.1002/mrm.70334","DOIUrl":"10.1002/mrm.70334","url":null,"abstract":"<p><strong>Purpose: </strong>To enable simultaneous free-breathing imaging of the entire lung and heart with isotropic resolution at 1.5 T for the diagnosis of cardiopulmonary disorders, while reducing scan time and minimizing the requirement for patient compliance.</p><p><strong>Methods: </strong>A three-dimensional radial dual-echo balanced steady-state free precession (bSSFP) sequence was developed to acquire cardiopulmonary data in a free-running fashion. All acquired data were binned into different respiratory and cardiac motion states according to respiratory and cardiac signals estimated from superior-inferior navigators. A novel subspace-based motion-compensation reconstruction algorithm was used to reconstruct five-dimensional (5D) cardiopulmonary images. Images acquired with the dual-echo bSSFP sequence were compared with those acquired using an ultrashort echo time gradient-echo (GRE-UTE) sequence. The proposed 5D imaging technique was also compared with respiration-resolved four-dimensional (4D) imaging in 12 healthy subjects.</p><p><strong>Results: </strong>The dual-echo bSSFP sequence effectively captured pulmonary signals while providing superior myocardium-blood contrast compared with the GRE-UTE sequence. Dynamic images of the entire lungs and heart were simultaneously obtained using the proposed 5D imaging technique. By minimizing the adverse effect of cardiac motion, 5D imaging yielded clearer depiction of cardiac structures and pulmonary structures adjacent to the heart than 4D imaging.</p><p><strong>Conclusion: </strong>A new simultaneous cardiopulmonary MRI technique was proposed in this study. Five-dimensional dynamic images of the entire lungs and heart with an isotropic resolution of 1.5 × 1.5 × 1.5 mm³ can be obtained from a single free-breathing scan of approximately 10 min. This technique has the potential for structural and functional assessment of the cardiopulmonary system.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"161-172"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147434186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Selective RF Pulses for Enhanced Signal Stability in Turbo Spin Echo Using a Differentiable Extended Phase Graph Model.","authors":"Madison M Augelli, Anuj Sharma, Mark A Griswold, William A Grissom","doi":"10.1002/mrm.70340","DOIUrl":"10.1002/mrm.70340","url":null,"abstract":"<p><strong>Purpose: </strong>To improve slice profile consistency across echo trains in turbo spin echo (TSE) imaging, thereby reducing image blurring and increasing the accuracy of multi echo spin echo <math> <semantics> <mrow> <msub><mrow><mi>T</mi></mrow> <mrow><mn>2</mn></mrow> </msub> </mrow> <annotation>$$ {T}_2 $$</annotation></semantics> </math> mapping.</p><p><strong>Methods: </strong>Excitation and refocusing RF pulses were optimized for TSE using a differentiable extended phase graph model that incorporates the spinor profiles of the RF pulses to calculate the magnetization slice profile across the echo train. The pulses were optimized using an L-BFGS algorithm in PyTorch to minimize an error term on the target signal magnitude with singular value regularization to promote similarity. The performance of the optimized pulses was assessed by comparing to time bandwidth-matched SLR RF pulses. Slice profile consistency was calculated in simulation and in a homogeneous phantom. Images were acquired in vivo to assess blurring artifacts, and <math> <semantics> <mrow> <msub><mrow><mi>T</mi></mrow> <mrow><mn>2</mn></mrow> </msub> </mrow> <annotation>$$ {T}_2 $$</annotation></semantics> </math> measurements were acquired in a NIST phantom and in vivo to assess improvements in accuracy.</p><p><strong>Results: </strong>The optimized pulses demonstrated superior performance over time bandwidth-matched SLR pulses, with a 90% reduction in the standard deviation of the normalized integrated signal at each echo. Optimized pulses increased sharpness in vivo at the edges of CSF and veins perpendicular to the phase-encoded direction, reduced <math> <semantics> <mrow> <msub><mrow><mi>T</mi></mrow> <mrow><mn>2</mn></mrow> </msub> </mrow> <annotation>$$ {T}_2 $$</annotation></semantics> </math> mapping error in the NIST phantom by 91%, and produced more accurate in vivo <math> <semantics> <mrow> <msub><mrow><mi>T</mi></mrow> <mrow><mn>2</mn></mrow> </msub> </mrow> <annotation>$$ {T}_2 $$</annotation></semantics> </math> maps.</p><p><strong>Conclusion: </strong>The optimization method enables flexible design of RF pulses in echo train pulse sequences with consistent slice profiles, achieving a target signal progression while also maintaining a constant phase and FWHM between echoes.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"214-226"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147444334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reducing Inhomogeneous MT (ihMT) Acquisition Time Using Frequency Alternation at Low Duty Cycle for Single Offset (FALSO) MT Preparations.","authors":"Gopal Varma, Aaron K Grant, Lucas Soustelle, Olivier M Girard, Guillaume Duhamel, David C Alsop","doi":"10.1002/mrm.70343","DOIUrl":"10.1002/mrm.70343","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate Frequency Alternation at Low duty cycle for Single Offset (FALSO) as a novel Magnetization Transfer (MT) preparation scheme to increase speed and/or spatial resolution of inhomogeneous MT (ihMT) MRI by reducing the number of volumes required.</p><p><strong>Methods: </strong>We compared FALSO MT to standard single frequency MT preparations using signal simulations and ihMT data acquired in a rat brain at 9.4 T and human brains at 3 T. Using FALSO MT preparations, combined with optimized Variable Flip Angle (VFA) MPRAGE readouts, we also acquired ihMT data at high resolution (down to 1.4 mm isotropic) to demonstrate the reduction in acquisitions required for ihMT images of sufficient SNR.</p><p><strong>Results: </strong>We found no statistically significant difference between ihMT ratios from data acquired using FALSO MT preparations versus averaging data following separate positive and negative frequency offset MT acquisitions (as in regular ihMT to account for MT asymmetry). Use of VFA (relative to constant flip angle) readouts allowed high-resolution ihMT images with a minimal number of volumes to be acquired and reduced variance in ihMT ratios within ROIs.</p><p><strong>Conclusion: </strong>FALSO MT preparations allow for a reduction in the number of acquisitions required for ihMT while still controlling for MT asymmetry. IhMT data acquired with VFA readouts allow for higher resolution acquisitions in the same scan time. The combination of FALSO MT and VFA readouts can be used to increase the spatial and/or temporal resolution of ihMT experiments, allowing for easier clinical translation and improving the utility of ihMT in neurological studies of myelin.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"191-202"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147458235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Double Asymmetric Spin Echo EPI (dASE-EPI) Enables fMRI of the Entire Rat Brain at 9.4 T.","authors":"Kyle A Johnson, Hanbing Lu, Jason W Sidabras","doi":"10.1002/mrm.70338","DOIUrl":"10.1002/mrm.70338","url":null,"abstract":"<p><strong>Purpose: </strong>Development and evaluation of a double asymmetric spin echo planar imaging (dASE-EPI) sequence to balance sensitivity to blood oxygenation level-dependent (BOLD) contrast with mitigation of susceptibility-induced intravoxel spin dephasing in ultra high-field rodent brain imaging.</p><p><strong>Methods: </strong>A dASE-EPI pulse sequence was implemented and resting-state BOLD fMRI was acquired in the rat brain. Data acquired with dASE-EPI were compared to conventional gradient-recalled EPI. Functional connectivity analyses were performed to assess detection of established networks and to evaluate signal recovery in regions affected by susceptibility (e.g., amygdala, hypothalamic nuclei).</p><p><strong>Results: </strong>dASE-EPI was found to provide BOLD sensitivity that was non-inferior to conventional GRE-EPI while substantially reducing susceptibility-related signal loss. Established functional networks including the bilateral insular, bilateral sensory, and default mode network were reliably detected with dASE-EPI. Functional connectivity of the amygdala, which was obscured in GRE-EPI, was recoverable with the proposed sequence.</p><p><strong>Conclusion: </strong>The proposed dASE-EPI pulse sequence is a viable solution when studying brain regions which suffer from severe susceptibility artifacts.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"366-373"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147444267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Diffusion and T2 Mapping Using RF-Modulated Phase-Based Gradient Echo Imaging.","authors":"Daiki Tamada, Ali Pirasteh, David F Jarrard, Diego Hernando, Scott B Reeder","doi":"10.1002/mrm.70312","DOIUrl":"10.1002/mrm.70312","url":null,"abstract":"<p><strong>Purpose: </strong>To introduce and evaluate the feasibility of a novel RF-phase modulated gradient echo (GRE) method for quantitative diffusion MRI, aimed at mitigating geometric distortion and enabling high-resolution 3D quantitative diffusion/T2 mapping as a complementary alternative to conventional DWI.</p><p><strong>Theory and methods: </strong>The proposed phase-based diffusion (PBD) method employs RF phase modulation to encode both diffusion and T2 information into the GRE signal phase. A closed-form analytical model enables joint apparent diffusion coefficient (ADC) and T2 mapping via iterative reconstruction. The method's feasibility was evaluated via Bloch equation simulations, phantom experiments, and preliminary in vivo imaging studies.</p><p><strong>Results: </strong>Monte Carlo simulations revealed that PBD provides more accurate median ADC estimates at low signal-to-noise ratios (SNRs) compared to conventional single-shot echo-planar imaging (SS-EPI), although PBD exhibited greater variability. Phantom studies demonstrated good agreement for PBD-derived ADC values (e.g., R² = 0.99) with reference methods and strong correlation for PBD-derived T2 values (e.g., R² = 0.89), though the latter showed some systematic bias in phantoms. In vivo results from patients with benign or malignant prostate disease demonstrated the feasibility of the PBD method to provide high-resolution ADC and T2 maps with minimal geometric distortions relative to conventional SS-EPI.</p><p><strong>Conclusion: </strong>PBD provides ADC and T2 maps with improved geometric fidelity in phantoms and in vivo, and offers robust median ADC estimates from noisy data based on simulations. This combination of spatial precision and noise characteristics makes PBD promising for applications such as high-resolution DWI for prostate MRI.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"49-65"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147433704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced 2D Spiral Cine DENSE MRI Using Low-Rank Denoising for Improved Apparent Signal-to-Noise Ratio, Spatial Resolution, Efficiency, Accuracy, and Accessibility.","authors":"Shu-Fu Shih, Yuxiao Wu, Siyue Li, Zhengyang Ming, Arutyun Pogosyan, Fei Han, Holden H Wu, J Paul Finn, Kim-Lien Nguyen, Xiaodong Zhong","doi":"10.1002/mrm.70331","DOIUrl":"10.1002/mrm.70331","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a denoising technique for displacement encoding with stimulated echoes (DENSE) MRI that improves spatial resolution, efficiency, and accuracy, and enhances accessibility by implementing DENSE MRI at 0.55 T.</p><p><strong>Methods: </strong>We developed a low-rank denoising technique, which leverages multidimensional spiral cine DENSE MRI data for empirical noise estimation via Monte Carlo simulation combined with automatic noise suppression. Thirty-six subjects (16 healthy, 20 with heart disease) were scanned at 3 T with breath-hold standard-resolution 2D cine DENSE (2.8 × 2.8 mm²) in a short-axis slice of the heart. In 10 healthy subjects, high-resolution DENSE with 1.2 × 1.2 mm² was acquired. Apparent signal-to-noise ratio (SNR), phase SNR, scan efficiency (SNR per heartbeat per unit voxel size), and standard deviation of segmental circumferential myocardial strain (E_cc) were compared with Wilcoxon signed-rank tests (p < 0.05 considered significant). High-resolution and standard-resolution DENSE results were compared using Bland-Altman analysis. Lastly, we scanned seven healthy subjects at 0.55 T and 3 T, and compared E_cc results.</p><p><strong>Results: </strong>Apparent magnitude SNR, phase SNR and scan efficiency were significantly improved after denoising in both standard-resolution and high-resolution DENSE (all p < 0.01). Bland-Altman analysis showed denoised high-resolution DENSE E_cc had smaller mean differences (non-denoised: 0.028 vs. denoised: 0.009) and narrower limits of agreement (non-denoised: [-0.072, 0.127] vs. denoised: [-0.048, 0.065]), indicating improved accuracy. Strain measurements from denoised DENSE at 0.55 T showed good agreement with those from 3 T, demonstrating feasibility of DENSE MRI at 0.55 T.</p><p><strong>Conclusion: </strong>Our proposed denoising technique may allow DENSE MRI with improved spatial resolution, efficiency, and accuracy, and enhanced accessibility at 0.55 T.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"403-419"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13050631/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147390294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Myocardial Sodium Quantification at 7 T Using Interleaved ²³Na/¹H pTx MRI With Motion and Anatomy-Based B₁ Correction.","authors":"Laurent Ruck, Nico Egger, Benedikt Zobler, Judith Schirmer, Sophia Nagelstraßer, Andreas Bitz, Tanja Platt, Simon Konstandin, Christoph Kopp, Michael Uder, Armin Michael Nagel","doi":"10.1002/mrm.70342","DOIUrl":"10.1002/mrm.70342","url":null,"abstract":"<p><strong>Purpose: </strong>To improve accuracy and repeatability of myocardial ²³Na quantification in cardiac MRI at 7 T by combining retrospective respiratory and cardiac motion correction with a novel anatomy-based B₁ bias field correction.</p><p><strong>Methods: </strong>In this study, a dual-nuclear interleaved ²³Na/¹H MRI sequence at 7 T was applied. Here, ¹H MR data enabled automated segmentation of myocardium and blood pool via nnUNet and facilitated respiratory and cardiac motion correction for both contrasts using ¹H navigators. For ²³Na MRI, a novel anatomy-based B₁ bias field correction was developed, estimating the transmit and receive (B₁) field bias from ¹H-derived segmentations and synthetic ²³Na images. All correction methods were validated through realistic simulations and in vivo studies. Repeatability was assessed in 10 healthy subjects, and the proposed B₁ correction was compared to phantom-based methods.</p><p><strong>Results: </strong>Respiratory and cardiac motion correction reduced quantification errors and improved SNR compared to conventional gating. The anatomy-based B₁ correction effectively mitigated errors caused by B₁ inhomogeneities and outperformed phantom-based methods in terms of repeatability. The measured apparent tissue sodium concentration of the myocardium after all corrections (49.5 <math> <semantics><mrow><mo>±</mo></mrow> <annotation>$$ pm $$</annotation></semantics> </math> 4.7 mM) was consistent with literature values. Combined motion and B₁ corrections improved repeatability, reducing the coefficient of repeatability from 4.9 mM (11.2%) without corrections to 2.0 mM (4.0%) after corrections.</p><p><strong>Conclusion: </strong>The combination of retrospective motion correction and anatomy-based B₁ bias field correction enables repeatable myocardial sodium quantification at 7 T. The interleaved acquisition facilitates robust segmentation and efficient use of ¹H MRI for motion and B₁ correction, providing a scalable framework for future clinical research studies.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"173-190"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147467917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of Fiber Orientation-Dependent R1 Relaxation in Human White Matter In Vivo Within The Framework of The Transient Hydrogen Bond Model.","authors":"Dmitriy A Yablonskiy, Risto A Kauppinen, Ekaterina Paasonen, Jeromy Thotland, Mervi Könönen, Pramod Pisharady, Christophe Lenglet, Juhana M Hakumäki, Olli H J Gröhn, Michael Garwood, Alexander L Sukstanskii","doi":"10.1002/mrm.70371","DOIUrl":"10.1002/mrm.70371","url":null,"abstract":"<p><strong>Purpose: </strong>Axon fiber orientation-dependent R1 relaxation in human white matter (WM) in vivo at B0 = 1.5 T, 3 T, and 7 T was studied within the framework of the transient hydrogen bond (THB) model, which attributes MR signal relaxation to quantum magnetization interactions of water and motion-restricted protons in hydrophilic heads of lipid bilayers forming cellular and myelinated membranes.</p><p><strong>Methods: </strong>R1 images by MP2RAGE MRI with microstructural DTI and NODDI indices by dMRI from WM were acquired. Angular R1 patterns were experimentally determined in WM with Orientation Dispersion Index (ODI) ranging from 0 to 0.2. The THB model was used to identify the biophysical parameters responsible for the R1 angular and field dependencies in quantitative terms.</p><p><strong>Results: </strong>At all B0s, non-monotonic R1 behavior was observed with higher R1 of axons perpendicular to the B0 direction and a broad, low R1 minimum centered around 40° fiber-to-field angles. The THB model with the same set of biophysical parameters yielded a good fit for R1 angular patterns in axon fibers oriented between 9.5° and 90° in respect to B0 at all fields. The experimental R1 values in the fibers between the 0° and 9.5° orientations showed an additional dip consistent with their inherent microstructural features. These fibers were found in the cortico-spinal tract with large and giant axons that would have a lower surface-to-volume ratio for forming THB, hence lower R1 relative to tracts with small-diameter axons.</p><p><strong>Conclusions: </strong>The data show that the THB model provides a robust physical framework for R1 relaxation anisotropy and B0 field dependence in vivo.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":"315-322"},"PeriodicalIF":3.0,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147609389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}