Magnetic Resonance in Medicine最新文献

{"title":"Quantitative susceptibility mapping of the human carotid artery: Assessing sensitivity to elastin and collagen ex vivo.","authors":"Alan J Stone, Brooke Tornifoglio, Francesco Digeronimo, Karin Shmueli, Caitríona Lally","doi":"10.1002/mrm.30500","DOIUrl":"https://doi.org/10.1002/mrm.30500","url":null,"abstract":"<p><strong>Purpose: </strong>The aim is to establish the relationship between carotid susceptibility and microstructural components in diseased carotid arteries.</p><p><strong>Methods: </strong>Excised cadaveric carotid arteries (n = 5) were scanned using high-resolution QSM at 7 Tesla. After ex vivo imaging, all samples were brought to histology and stained for elastin, collagen, cells, and calcium. An image registration pipeline was used in combination with semi-quantitative, regional histology analysis to evaluate relationships between MRI and microstructural components.</p><p><strong>Results: </strong>Weak, non-significant (p > 0.05) correlations were found between all components and regional magnitude and R₂* measurements. A significant, moderate negative correlation between the elastin fraction and regional magnetic susceptibility, r_elastin = -0.63 (p < 0.0001) was found, as well as a significant, moderate negative correlation between collagen and regional magnetic susceptibility, r_collagen = -0.59 (p < 0.0001).</p><p><strong>Conclusion: </strong>Tissue magnetic susceptibility in diseased human carotid arteries was shown to be significantly correlated with the dominant microstructural components of pathological human cadaver samples-elastin and collagen. Knowing that elastin and collagen are disrupted in vascular disease progression, QSM offers clinically translatable potential for novel disease biomarkers.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143730315","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":"Motion-corrected brain MRI at ultralow field (64 mT).","authors":"Yannick Brackenier, Rui Pedro Teixeira, Lucilio Cordero-Grande, Emil Ljungberg, Niall J Bourke, Tomoki Arichi, Sean Deoni, Steve C R Williams, Joseph V Hajnal","doi":"10.1002/mrm.30506","DOIUrl":"https://doi.org/10.1002/mrm.30506","url":null,"abstract":"<p><strong>Purpose: </strong>The study investigates the feasibility of applying a retrospective motion-correction technique to ultralow-field (ULF) MRI data to improve reconstructed image quality when there is patient motion, which is likely to be a critical challenge in portable, point-of-care imaging.</p><p><strong>Theory & methods: </strong>The study tests alignedSENSE, an iterative motion correction and reconstruction method with SENSE, for ULF MRI, with additional corrections to estimate and correct within-scan phase variations. The method was applied to in vivo brain volumetric data acquired from five healthy volunteers using a 64 mT portable MRI scanner. The volunteers underwent different motion types and levels, with corrections evaluated using both visual and quantitative metrics.</p><p><strong>Results: </strong>Motion correction, particularly when within-scan phase variations are also accounted for, showed clear improvements in image quality. Without making any assumptions about the origin of these phase variations, incorporating them into the signal model and jointly estimating with the image/motion parameters increases the data consistency. This improves the image quality and motion parameters across various levels of induced motion. Quantitative analysis confirmed that the combined motion and phase corrections outperformed conventional parallel imaging reconstruction, although extreme motion cases still pose challenges.</p><p><strong>Conclusion: </strong>The study demonstrates that alignedSENSE motion-correction techniques can be effectively applied to ULF MRI systems. The results suggest that these techniques can substantially enhance image quality without increasing scan time, which could make ULF MRI more clinically viable for point-of-care deployment.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143730312","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":"Regionally resolved cardiac metabolism using a dipole-loop array coil for 7 T ³¹P-MRSI.","authors":"Jabrane Karkouri, Will Watson, Ria Forner, Jonathan R Weir-McCall, Tracy Horn, Marion Hill, Stephen Hoole, Dennis Klomp, Christopher T Rodgers","doi":"10.1002/mrm.30492","DOIUrl":"https://doi.org/10.1002/mrm.30492","url":null,"abstract":"<p><strong>Purpose: </strong>We introduce a novel commercial phosphorus-31 (³¹P) dipole-loop array coil, describing the coil hardware and testing its performance on phantoms. We used this coil to assess cardiac metabolism per region in healthy volunteers.</p><p><strong>Methods: </strong>B₁ ⁺ field maps were simulated and compared to maps measured with a set of CSI sequences with varying voltages. Seventeen volunteers were scanned with 7 T phosphorus-31 magnetic resonance spectroscopic imaging (³¹P-MRSI). Reproducibility was assessed in nine of these volunteers. Strain was measured for six of these volunteers at 3 T.</p><p><strong>Results: </strong>Blood- and saturation-corrected Phosphocreatine/γ-adenosine triphosphate (PCr/ATP) ratios were measured for four regions of the left ventricle: 1.86 in septum, 2.25 in anterior wall, 1.41 in inferior wall, and 1.53 in lateral wall, respectively. These are in the expected range compared to previous studies. B₁ ⁺ maps show good signal uniformity around the position of the heart (0.13 ± 0.06 μT/sqrt(W)). Intrasession and intersession coefficients of reproducibility were 0.22-0.88 and 0.29-0.79, respectively. Linear modeling shows that regional PCr/γATP correlates with circumferential strain but not radial strain. This requires corroboration by a larger study including patients with impaired function and energetics.</p><p><strong>Conclusion: </strong>Dipole-loop array coils present a promising new approach for human cardiac ³¹P-MRSI at 7 T. Their favorable B₁ ⁺ uniformity at depth and specific absorption rate over loop arrays and improved SNR when combined with loops for reception could be beneficial for further clinical studies measuring energetics by ³¹P-MRSI at 7 T. The new capability to assess PCr/γATP ratios across the whole left ventricle could enable clinical studies to investigate regional changes in cardiac energetics for the first time.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143691830","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":"Improving fat saturation robustness in outer extremity MRI with a local shim coil insert","authors":"Ziyang Long,&nbsp;Hsin-Jung Yang,&nbsp;Nader Binesh,&nbsp;Archana Vadiraj Malagi,&nbsp;Yun Shang,&nbsp;Li-ting Huang,&nbsp;Jeremy Zepeda,&nbsp;Fardad Michael Serry,&nbsp;Debiao Li,&nbsp;Hui Han","doi":"10.1002/mrm.30474","DOIUrl":"10.1002/mrm.30474","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>High-quality fat suppression is essential for various MRI applications. In musculoskeletal imaging, poor fat suppression caused by severe B₀ inhomogeneity can obscure important lesions, potentially leading to inaccurate diagnoses. This problem is particularly exacerbated in off-isocenter imaging, where conventional shimming using second-order spherical harmonic shim coils often proves inadequate due to elevated B₀ inhomogeneity. To address this challenge, we configured a simple local shim insert to provide additional localized B₀ shimming for off-isocenter regions, offering a practical hardware solution.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We designed and constructed a seven-channel shim coil and evaluated its performance in comparison to conventional second-order spherical harmonic shimming within a targeted volume near the scanner bore. The coil was tested with both phantom and in vivo studies using a clinical 3 T MRI scanner.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The improved B₀ homogeneity achieved with the local shim coil significantly enhanced fat saturation (fat–sat) uniformity across the imaged volumes. This improvement was particularly beneficial for areas far from the scanner isocenter, where B₀ inhomogeneity is most severe. Our results indicated a 40% reduction in RMS error of the B₀ field for elbow imaging and 35% for hand imaging, highlighting substantial improvements in B₀ field homogeneity. Additionally, the image quality score increased by 1 point for both hand and elbow images, reflecting enhanced fat–sat quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The simple local shim insert we configured improves fat–sat capability in both hand and elbow imaging. It offers the potential for improving off-isocenter musculoskeletal MRI.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"94 1","pages":"401-413"},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663503","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":"Feasibility of magnetic resonance elastography in the healthy rat heart.","authors":"Lisa Smith, Vidar Magne Skulberg, Lili Zhang, Ivar Sjaastad, Emil Knut Stenersen Espe","doi":"10.1002/mrm.30504","DOIUrl":"https://doi.org/10.1002/mrm.30504","url":null,"abstract":"<p><strong>Purpose: </strong>Develop a MR elastography (MRE) protocol to detect in vivo cardiac stiffness in rats.</p><p><strong>Methods: </strong>This study was approved by the National Animal Research Authority. A healthy, adult, male Sprague-Dawley rat underwent cardiac MRE. A specialized direct shaking cardiac MRE setup and MRI protocol were designed. Stiffness was measured at 15 cardiac phases. A single midventricular slice was acquired, and intrasession variability was measured. A direct inversion of the Helmholtz equation was used to calculate the stiffness from MRE images.</p><p><strong>Results: </strong>In the healthy rat, the early systolic stiffness was 2.90 kPa. The stiffness increased to the end systole (3.81 kPa), followed by a reduction during diastole to 2.61 kPa. The intrasession correlation was ρ = 0.88 (p < 0.001).</p><p><strong>Conclusion: </strong>This study demonstrates the feasibility of cardiac MRE in rats. Our results confirm that cardiac stiffness increases from early systole to end systole, followed by a decrease in diastole.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663546","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":"Gradient system characterization of a 1.5 T MR-Linac with application to 4D UTE imaging for adaptive MR-guided radiotherapy of lung cancer","authors":"Rosie Goodburn,&nbsp;Tom Bruijnen,&nbsp;Bastien Lecoeur,&nbsp;Prashant Nair,&nbsp;Merina Ahmed,&nbsp;Helen Barnes,&nbsp;Uwe Oelfke,&nbsp;Andreas Wetscherek","doi":"10.1002/mrm.30505","DOIUrl":"10.1002/mrm.30505","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To measure the gradient system transfer function (GSTF) of an MR-Linac (Elekta Unity, Stockholm, Sweden) using an accessible phantom-based method and to apply trajectory corrections for UTE image reconstruction in the context of MR-guided radiotherapy of lung cancer.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The first-order GSTF of a 1.5 T, split gradient Elekta Unity MR-Linac was measured using a thin-slice technique to characterize gradient system imperfections for each physical gradient axis (X, Y, Z). Repeatability measurements of the GSTF were performed 48 h apart. The GSTF was applied to trajectory correction in multi-echo UTE image reconstruction (TEs = 0.176, 1.85, 3.52 ms) to allow for UTE-Dixon inputs in the generation of synthetic CT. Images were acquired in an anthropomorphic phantom and in two free-breathing lung cancer patients. For patient scans, respiratory-correlated 4D-MR images were reconstructed using self-navigation and an iterative compressed-sensing algorithm.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The GSTF magnitude was similar across the X/Y/Z axes up to ˜6 kHz. The GSTF phase was similar between the X/Y/Z components up to ˜3 kHz. Repeatability measurements demonstrated minimal variations corresponding to a system delay difference of 0.06 μs. Corrected UTE trajectory spokes are shifted approximately 1 m⁻¹ compared to the nominal <i>k</i>-space location. Corrected phantom and patient UTE images exhibited improved signal uniformity and contrast and reduced halo and signal loss artifacts. Trajectory correction for the later TE images did not improve overall image quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The proposed GSTF measurement method using standard MR-Linac hardware enables successful trajectory correction in UTE imaging reconstruction, with applications to lung synthetic CT generation for MR-guided radiotherapy.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"94 1","pages":"28-40"},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30505","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663549","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":"Referenceless 4D flow MRI using radial balanced SSFP at 0.6 T.","authors":"Charles McGrath, Pietro Dirix, Vincent Vousten, Jouke Smink, Ece Ercan, Peter Börnert, Sebastian Kozerke","doi":"10.1002/mrm.30503","DOIUrl":"https://doi.org/10.1002/mrm.30503","url":null,"abstract":"<p><strong>Purpose: </strong>To implement four-dimensional-flow MRI using phase-contrast balanced steady-state free precession (bSSFP) at 0.6 T using a free-running three-dimensional (3D) radial trajectory and referenceless background phase correction.</p><p><strong>Methods: </strong>A free-running, wobbling Archimedean spiral approach including bipolar velocity-encoding gradients (3D PC-bSSFP) was implemented on a 0.6T prototype scanner. Bipolar rewinder gradients were added to ensure first-moment nulling per repetition time. Velocity encoding was performed using a three-point encoding scheme (i.e., omitting a reference measurement). Advanced computer simulations were carried out to validate the approach. Image reconstruction was performed using a locally low-rank approach. Results for anatomical visualization and flow quantification were reconstructed separately with different regularization factors. Background phase correction was achieved using phase estimation on time-averaged reconstructions. In vivo data were acquired in 6 healthy subjects during free breathing. Additional two-dimensional (2D) phase-contrast spoiled gradient-echo (2D PC-GRE) breath-hold data were obtained for reference to compare flow values in the ascending aorta, descending aorta, and pulmonary trunk.</p><p><strong>Results: </strong>Velocity data acquired with 3D PC-bSSFP compared well with 2D PC-GRE (root mean square error = 3.96 cm/s), with minor underestimation of velocities (-0.52 cm/s). Cardiac phase-dependent signal-to-noise ratios normalized for differences in scan time and resolution between 3D PC-bSSFP and 2D PC-GRE demonstrate relatively steady values for 3D PC-bSSFP when compared to 2D PC-bSSFP with some reduction during phases of high flow.</p><p><strong>Conclusion: </strong>Free-running, referenceless, four-dimensional-flow MRI using radial 3D PC-bSSFP is feasible on a lower-field 0.6T system, producing adequate flow quantification while yielding simultaneously reasonable cine images for concurrent flow and functional assessment of the heart and great vessels.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663721","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":"Simultaneous 3D quantitative magnetization transfer imaging and susceptibility mapping.","authors":"Albert Jang, Kwok-Shing Chan, Azma Mareyam, Jason Stockmann, Susie Yi Huang, Nian Wang, Hyungseok Jang, Hong-Hsi Lee, Fang Liu","doi":"10.1002/mrm.30493","DOIUrl":"https://doi.org/10.1002/mrm.30493","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;Introduce a unified acquisition and modeling strategy to simultaneously quantify magnetization transfer (MT), tissue susceptibility ( &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;χ&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ chi $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt; &lt;mo&gt;*&lt;/mo&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; .&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Theory and methods: &lt;/strong&gt;Magnetization transfer is induced through the application of off-resonance irradiation between excitation and acquisition of an RF-spoiled gradient-echo scheme, where free pool spin-lattice relaxation ( &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1^{mathrm{F}} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ), macromolecular proton fraction ( &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ f $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) and magnetization exchange rate ( &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {k}_{mathrm{F}} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) were calculated by modeling the magnitude of the MR signal using a binary spin-bath MT model with &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;B&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt; &lt;mo&gt;+&lt;/mo&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {B}_1^{+} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; inhomogeneity correction via Bloch-Siegert shift. Simultaneously, a multi-echo acquisition is incorporated into this framework to measure the time evolution of both signal magnitude and phase, which was further modeled for estimating &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt; &lt;mo&gt;*&lt;/mo&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and tissue susceptibility. In this work, we demonstrate the feasibility of this new acquisition and modeling strategy in vivo on the brain tissue.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;In vivo brain experiments were conducted on five healthy subjects to validate our method. Utilizing an analytically derived signal model, we simultaneously obtained 3D &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt; &lt;mn&gt;1&lt;/mn&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1^{mathrm{F}} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; , &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ f $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; , &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;F&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {k}_{mathrm{F}} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; , &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;χ&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ chi $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt; &lt;mo&gt;*&lt;/mo&gt;&lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; maps of the whole brain. Our results from the brain regional analysis show good agreement with those previously reported in the literature, which used separate MT and QSM methods.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;A unified acquisition and modeling strategy based ","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143649576","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":"Magnetization transfer explains most of the T1 variability in the MRI literature","authors":"Jakob Assländer,&nbsp;Sebastian Flassbeck","doi":"10.1002/mrm.30451","DOIUrl":"10.1002/mrm.30451","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To identify the predominant source of the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; variability described in the literature, which ranges from 0.6–1.1 s for brain white matter at 3 T.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;25 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;-mapping methods from the literature were simulated with a mono-exponential and various magnetization-transfer (MT) models, each followed by mono-exponential fitting. A single set of model parameters was assumed for the simulation of all methods, and these parameters were estimated by fitting the simulation-based to the corresponding literature &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; values of white matter at 3 T. We acquired in vivo data with a quantitative magnetization transfer and three &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;-mapping techniques. The former was used to synthesize MR images that correspond to the three &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 ","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"94 1","pages":"293-301"},"PeriodicalIF":3.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143649604","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":"Magnetization transfer imaging using non-balanced SSFP at ultra-low field.","authors":"Sharada Balaji, Neale Wiley, Adam Dvorak, Francesco Padormo, Rui P A G Teixiera, Megan E Poorman, Alex MacKay, Tobias Wood, Adam R Cassidy, Anthony Traboulsee, David K B Li, Irene Vavasour, Steven C R Williams, Sean C L Deoni, Emil Ljungberg, Shannon H Kolind","doi":"10.1002/mrm.30494","DOIUrl":"https://doi.org/10.1002/mrm.30494","url":null,"abstract":"<p><strong>Purpose: </strong>Ultra-low field MRI scanners have the potential to improve health care delivery, both through improved access in areas where there are few MRI scanners and allowing more frequent monitoring of disease progression and treatment response. This may be particularly true in white matter disorders, including leukodystrophies and multiple sclerosis, in which frequent myelin-sensitive imaging, such as magnetization transfer (MT) imaging, might improve clinical care and patient outcomes.</p><p><strong>Methods: </strong>We implemented an on-resonance approach to MT imaging on a commercial point-of-care 64 mT scanner using a non-balanced steady-state free precession sequence. Phantom and in vivo experiments were used to evaluate and optimize the sequence sensitivity and reproducibility, and to demonstrate in vivo performance and inter-site reproducibility.</p><p><strong>Results: </strong>From phantom experiments, T₁ and T₂ effects were determined to have a negligible effect on the differential MT weighting. MT ratio (MTR) values in white matter were 23.1 ± 1.0% from 10 healthy volunteers, with an average reproducibility coefficient of variation of 1.04%. Normal-appearing white matter MTR values in a multiple sclerosis participant (21.5 ± 6.2%) were lower, but with a similar spread of values, compared to an age-matched healthy volunteer (23.3 ± 6.2%).</p><p><strong>Conclusion: </strong>An on-resonance MT imaging approach was developed at 64 mT that can be performed in as little as 4 min. A semi-quantitative myelin-sensitive imaging biomarker at this field strength is available for assessing both myelination and demyelination.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143649606","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}