Magnetic Resonance in Medicine最新文献

{"title":"Automated fibrosis segmentation from wideband post-contrast \u0000 \u0000 \u0000 \u0000 \u0000 T\u0000 \u0000 \u0000 1\u0000 \u0000 \u0000 ∗\u0000 \u0000 \u0000 \u0000 $$ {T}_1^{ast } $$\u0000 mapping in an animal model of ischemic heart disease with implantable cardioverter-defibrillators","authors":"Calder D. Sheagren, Terenz Escartin, Jaykumar H. Patel, Jennifer Barry, Graham A. Wright","doi":"10.1002/mrm.30468","DOIUrl":"10.1002/mrm.30468","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Post-contrast <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mrow>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 <mrow>\u0000 <mo>∗</mo>\u0000 </mrow>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {T}_1^{ast } $$</annotation>\u0000 </semantics></math> mapping has proven promising for automated scar segmentation in subjects without ICDs, but this has not been implemented in patients with ICDs. We introduce an automated cluster-based thresholding method for <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mrow>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 <mrow>\u0000 <mo>∗</mo>\u0000 </mrow>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {T}_1^{ast } $$</annotation>\u0000 </semantics></math> maps with an ICD present and compare it to manually tuned thresholding of synthetic LGE images with an ICD present and standard LGE without an ICD present.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Seven swine received an ischemia-reperfusion myocardial infarction and were imaged at 3 T 4–5 weeks post-infarct with and without an ICD. Mapping-based thresholding was performed using synthetic LGE and artifact-corrected cluster-thresholding methods, both employing connected component filtering. Standard pixel signal intensity thresholding was performed on the conventional LGE without an ICD. Volumetric accuracy is relative to conventional LGE and Dice similarity between SynLGE and cluster-based segmentations were evaluated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>No statistical significance was observed between LGE volumes without an ICD and both SynLGE and artifact-corrected cluster-threshold volumes with an ICD, when using connected component filtering. Additionally, Dice alignment between SynLGE and cluster-thresholding was high for healthy myocardium (0.96), dense scar (0.83), and dense scar union gray","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 6","pages":"2401-2413"},"PeriodicalIF":3.0,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30468","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597376","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":"Elastographic magnetization prepared imaging with rapid encoding","authors":"Alex M. Cerjanic, Alexa M. Diano, Curtis L. Johnson","doi":"10.1002/mrm.30482","DOIUrl":"10.1002/mrm.30482","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To introduce a novel sequence for achieving fast, whole-brain MR elastography data through the introduction of a magnetization preparation block for motion encoding along with rapid imaging readouts.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Theory and Methods</h3>\u0000 \u0000 <p>We implemented MRE motion encoding in a magnetization preparation pulse sequence block, where spins are excited, motion encoded, and then stored longitudinally. This magnetization is accessed through a train of rapid gradient echoes and encoded with a 3D stack-of-spirals trajectory. Spoilers are included to crush unprepared magnetization and avoid image artifacts. We demonstrate the feasibility of the proposed method in capturing MRE displacement data for estimating mechanical properties and accelerating scan times.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We measured stability of phase across gradient echo readouts in the readout train after magnetization preparation. Additionally, we obtained displacement fields with high OSS-SNR with retrospective sampling and differences in average stiffness properties (NRMSE) of 3.6% (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mi>x</mi>\u0000 <mi>y</mi>\u0000 </mrow>\u0000 </msub>\u0000 <mo>=</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation>$$ {R}_{xy}=2 $$</annotation>\u0000 </semantics></math>) and 7.7% (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mi>x</mi>\u0000 <mi>y</mi>\u0000 </mrow>\u0000 </msub>\u0000 <mo>=</mo>\u0000 <mn>4</mn>\u0000 </mrow>\u0000 <annotation>$$ {R}_{xy}=4 $$</annotation>\u0000 </semantics></math>) between retrospectively undersampled and fully sampled data. Prospective undersampling showed highly similar multiscale similarity measures and global property differences between 1.0% to 3.5% with one outlier of 8.1% between the proposed method and reference EPI scans.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Magnetization pre","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 6","pages":"2444-2455"},"PeriodicalIF":3.0,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597378","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":"Ultra-high temporal resolution 4D angiography using arterial spin labeling with subspace reconstruction","authors":"","doi":"10.1002/mrm.30496","DOIUrl":"https://doi.org/10.1002/mrm.30496","url":null,"abstract":"","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 5","pages":"C1"},"PeriodicalIF":3.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30496","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143595297","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":"Real-time fetal brain and placental T2* mapping at 0.55T MRI.","authors":"Jordina Aviles Verdera, Sara Neves Silva, Kelly M Payette, Raphael Tomi-Tricot, Megan Hall, Lisa Story, Shaihan J Malik, Joseph V Hajnal, Mary A Rutherford, Jana Hutter","doi":"10.1002/mrm.30497","DOIUrl":"https://doi.org/10.1002/mrm.30497","url":null,"abstract":"<p><strong>Purpose: </strong>To provide real-time, organ-specific quantitative information - specifically placental and fetal brain T2 * - to optimize and personalize fetal MRI examinations.</p><p><strong>Methods: </strong>A low-latency setup enables real-time processing, including segmentation, T2* fitting, and centile calculation. Two nnU-Nets were trained on 2 989 fetal brains, and 540 placental datasets for automatic segmentation. Normative T2* curves over gestation were derived from 88 healthy cases. Prospective testing included 50 fetal MRI scans: A validation cohort (10 exams with three intra-scan repetitions) and an evaluation cohort (40 participants). Validation was performed with Bland-Altman assessments and Dice coefficients between repetitions, manual/automatic segmentations, and online/offline quantification.</p><p><strong>Results: </strong>T2* maps and centiles for the fetal brain and placenta were available in under one minute for all cases. The validation cohort showed robust reproducibility, with intra-scan mean T2* differences of 1.04, -3.17, and 5.07 ms for the fetal brain and -3.15, 4.74, and 2.45 ms for the placenta. Mean T2* differences between online and offline processing were 1.63 ms and 0.16 ms for the fetal brain and placenta, respectively. Dice coefficients were <math> <semantics><mrow><mn>0</mn> <mo>.</mo> <mn>84</mn> <mo>±</mo> <mn>0</mn> <mo>.</mo> <mn>02</mn></mrow> <annotation>$$ 0.84pm 0.02 $$</annotation></semantics> </math> for the placenta and <math> <semantics><mrow><mn>0</mn> <mo>.</mo> <mn>96</mn> <mo>±</mo> <mn>0</mn> <mo>.</mo> <mn>01</mn></mrow> <annotation>$$ 0.96pm 0.01 $$</annotation></semantics> </math> for the fetal brain.</p><p><strong>Conclusions: </strong>Real-time quantitative imaging supports personalized MR exams, optimizing sequence selection and working towards reducing recall rates. The ability to assess T2*, a potential biomarker for pregnancy complications, in real-time opens new clinical possibilities. Future research will apply this pipeline to pregnancies affected by preeclampsia and growth restriction and explore MR-guided fetal interventions.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597033","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":"Interleaved 23Na/1H MRI of the human heart at 7 T using a combined 23Na/1H coil setup and 1H parallel transmission","authors":"Laurent Ruck,&nbsp;Nico Egger,&nbsp;Tobias Wilferth,&nbsp;Judith Schirmer,&nbsp;Lena Vanessa Gast,&nbsp;Sophia Nagelstraßer,&nbsp;Saskia Wildenberg,&nbsp;Andreas Bitz,&nbsp;Titus Lanz,&nbsp;Tanja Platt,&nbsp;Simon Konstandin,&nbsp;Christoph Kopp,&nbsp;Michael Uder,&nbsp;Armin Michael Nagel","doi":"10.1002/mrm.30426","DOIUrl":"10.1002/mrm.30426","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To evaluate the feasibility of interleaved ²³Na/¹H cardiac MRI at 7 T using ¹H parallel transmission (pTx) pulses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A combined setup consisting of a ²³Na volume coil and two ¹H transceiver arrays was employed and the transmit and receive characteristics were compared in vitro with those of the uncombined radiofrequency coils. Furthermore, the implemented interleaved ²³Na/¹H pTx sequence was validated in phantom measurements and applied to four healthy subjects. For the latter, three customized ¹H excitation pulses (universal and individual phase shims (UPS/IPS) and individual 4kT pulses (4kT)) were employed in the interleaved ²³Na/¹H pTx sequence and compared with the vendor-provided default cardiac phase shim (DPS).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Combining both coils resulted in a reduction of the mean ²³Na transmit field (B₁⁺) efficiency and ²³Na signal-to-noise ratio by 18.9% and 15.4% for the combined setup, whereas the ¹H B₁⁺ efficiency was less influenced (−4.7%). Compared with single-nuclear acquisitions, interleaved dual-nuclear ²³Na/¹H MRI showed negligible influence on ²³Na and ¹H image quality. For all three customized ¹H pTx pulses the B₁⁺ homogeneity was improved (coefficients of variation: CV_UPS = 0.30, CV_IPS = 0.23, CV_4kT = 0.15) and no ¹H signal dropouts occurred compared with the vendor-provided default phase shim (CV_DPS = 0.37).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The incorporation of customized ¹H pTx pulses in an interleaved ²³Na/¹H sequence scheme was successfully demonstrated at 7 T and improvements of the ¹H B₁⁺ homogeneity within the heart were shown. Combining interleaved ²³Na/¹H MRI with ¹H pTx is an important tool to enable robust quantification of myocardial tissue sodium concentrations at 7 T within clinically acceptable acquisition times.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"94 1","pages":"231-241"},"PeriodicalIF":3.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30426","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597012","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":"High-resolution, volumetric diffusion-weighted MR spectroscopic imaging of the brain.","authors":"Zepeng Wang, Bradley P Sutton, Fan Lam","doi":"10.1002/mrm.30479","DOIUrl":"https://doi.org/10.1002/mrm.30479","url":null,"abstract":"<p><strong>Purpose: </strong>To achieve high-resolution, three-dimensional (3D) quantitative diffusion-weighted MR spectroscopic imaging (DW-MRSI) for molecule-specific microstructural imaging of the brain.</p><p><strong>Methods: </strong>We introduced and integrated several innovative acquisition and processing strategies for DW-MRSI: (a) a new double-spin-echo sequence combining selective excitation, bipolar diffusion encoding, rapid spatiospectral sampling, interleaved water spectroscopic imaging data, and a special sparsely sampled echo-volume-imaging (EVI)-based navigator, (b) a rank-constrained time-resolved reconstruction from the EVI data to capture spatially varying phases, (c) a model-based phase correction for DW-MRSI data, and (d) a multi-b-value subspace-based method for water/lipids removal and spatiospectral reconstruction using learned metabolite subspaces, and e) a hybrid subspace and parametric model-based parameter estimation strategy. Phantom and in vivo experiments were performed to validate the proposed method and demonstrate its ability to map metabolite-specific diffusion parameters in 3D.</p><p><strong>Results: </strong>The proposed method generated reproducible metabolite diffusion coefficient estimates, consistent with those from a standard single-voxel DW spectroscopy (SV-DWS) method. High-SNR multi-molecular mean diffusivity (MD) maps can be obtained at a 6.9  <math> <semantics><mrow><mo>×</mo></mrow> <annotation>$$ times $$</annotation></semantics> </math> 6.9 <math> <semantics><mrow><mo>×</mo></mrow> <annotation>$$ times $$</annotation></semantics> </math> 7.0 mm <math> <semantics> <mrow> <msup><mrow><mo> </mo></mrow> <mn>3</mn></msup> </mrow> <annotation>$$ {}^3 $$</annotation></semantics> </math> nominal resolution with large 3D brain coverage. High-resolution (4.4 <math> <semantics><mrow><mo>×</mo></mrow> <annotation>$$ times $$</annotation></semantics> </math> 4.4 <math> <semantics><mrow><mo>×</mo></mrow> <annotation>$$ times $$</annotation></semantics> </math> 5.6 mm <math> <semantics> <mrow> <msup><mrow><mo> </mo></mrow> <mrow><mn>3</mn></mrow> </msup> </mrow> <annotation>$$ {}^3 $$</annotation></semantics> </math> ) metabolite and diffusion coefficient maps can be obtained within 20 mins for the first time. Tissue-dependent metabolite MDs were observed, i.e., larger MDs for NAA, creatine, and choline in white matter than gray matter, with region-specific differences.</p><p><strong>Conclusion: </strong>We demonstrated an unprecedented capability of simultaneous, high-resolution metabolite and diffusion parameter mapping. This imaging capability has strong potential to offer richer molecular and tissue-compartment-specific microstructural information for various clinical and neuroscience applications.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143596920","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":"Toward optimal inline respiratory motion correction for in vivo cardiac diffusion tensor MRI using symmetric and inverse-consistent deformable image registration.","authors":"Yuchi Liu, Danielle Kara, Thomas Garrett, Shi Chen, Daniel Wee, Ning Jin, Peter Speier, Hiroshi Nakagawa, Pasquale Santangeli, Michael A Bolen, Oussama Wazni, Mazen Hanna, W H Wilson Tang, Animesh Tandon, Deborah Kwon, Xiaoming Bi, Christopher Nguyen","doi":"10.1002/mrm.30485","DOIUrl":"https://doi.org/10.1002/mrm.30485","url":null,"abstract":"<p><strong>Purpose: </strong>This study aims to develop a free-breathing cardiac DTI method with fast and robust motion correction.</p><p><strong>Methods: </strong>Two proposed image registration-based motion correction (MOCO) strategies, MOCO_Naive and MOCO_Avg, were applied to diffusion-weighted images acquired with M2 diffusion gradients under free-breathing. The effectiveness of MOCO was assessed by tracking epicardium pixel positions across image frames. Resulting mean diffusivity (MD), fractional anisotropy (FA), and helix angle (HA) maps were compared against a previous low rank tensor based MOCO method (MOCO_LRT) in 20 healthy volunteers and two patients scanned at 3 T.</p><p><strong>Results: </strong>Compared with the MOCO_LRT method, both proposed MOCO_Naive and MOCO_Avg methods generated slightly lower MD and helix angle transmurality (HAT) magnitude values, and significantly lower FA values. Moreover, both proposed MOCO methods achieved significantly smaller SDs of MD and FA values, and more smoothly varying helical structure in HA maps in healthy volunteers, indicating more effective MOCO. Elevated MD, decreased FA, and lower HAT magnitude were observed in two patients compared with healthy volunteers. Furthermore, the computing speed of image registration-based MOCO is twice as fast as the LRT method on the same dataset and same workstation.</p><p><strong>Conclusion: </strong>This study demonstrates a fast and robust motion correction approach using image registration for in vivo free-breathing cardiac DTI. It improves the quality of quantitative diffusion maps and will facilitate clinical translation of cardiac DTI.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597091","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":"Accelerating spin-echo EPI through combined patterned multislice excitation and simultaneous multislice acquisition","authors":"Jiazheng Zhou,&nbsp;Peter van Gelderen,&nbsp;Jacco A. de Zwart,&nbsp;Yicun Wang,&nbsp;Jeff H. Duyn","doi":"10.1002/mrm.30472","DOIUrl":"10.1002/mrm.30472","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To demonstrate further acceleration of spin echo MRI by combining the simultaneous multi-slice approach with the recently introduced patterned multislice excitation (PME) technique and evaluate application for rapid diffusion-weighted MRI.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Theory and Methods</h3>\u0000 \u0000 <p>Implementation at 3T involved the design of RF pulses simultaneously acting on four separate slices within hardware limits on peak amplitude. This was accomplished by time-shifted sub-pulses and a dedicated switching scheme of the slice-select gradient. The new technique was evaluated on two clinical MRI systems with differing maximum gradient strength.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Four-fold acceleration was successfully achieved by combining PME with rate-2 SMS. Within fixed measurement time, the proposed approach allows increased averaging or more elaborate sampling of diffusion tensor space. Depending on implementation, gains in SNR per unit time were modest or small, which is attributed to out-of-slice saturation effects of the RF pulses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Combination of PME with SMS-2 for further acceleration of diffusion imaging is feasible at 3T.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 6","pages":"2499-2506"},"PeriodicalIF":3.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30472","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542459","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":"Diffusion tensor subspace imaging of double diffusion–encoded MRI delineates small fibers and gray-matter microstructure not visible with single encoding techniques","authors":"Elizabeth B. Hutchinson,&nbsp;Jean-Philippe Galons,&nbsp;Courtney J. Comrie,&nbsp;Thomas G. Beach,&nbsp;Geidy E. Serrano,&nbsp;Mark W. Bondi,&nbsp;Seraphina K. Solders,&nbsp;Vitaly L. Galinsky,&nbsp;Lawrence R. Frank","doi":"10.1002/mrm.30463","DOIUrl":"10.1002/mrm.30463","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Double diffusion encoding (DDE) acquisition strategies promise specificity for small-dimensional structures inaccessible to single diffusion encoding (SDE). For DDE-weighted MRI scans to become relevant for whole brain imaging, signal reconstruction frameworks must accurately report microstructural features of interest—especially microscale anisotropy in complex tissue environments. This study examined the recently developed diffusion tensor subspace imaging (DiTSI) framework and its radial and spherical anisotropy metrics (RA and SA, respectively) in postmortem human brain tissue specimens.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>MRI microscopy including multishell SDE-weighted and DDE-weighted imaging was performed for healthy brain stem and temporal lobe specimens and for specimens with Alzheimer's disease pathology and neurodegeneration. The DiTSI framework was compared with four other diffusion MRI frameworks, and angular and radial DDE sampling were evaluated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>DDE acquisition and the DiTSI metric maps of SA and RA in temporal lobe and brain-stem specimens were found to be distinct from fractional anisotropy and orientation dispersion index in providing complementary and selective contrast of microscale anisotropy at the gray-matter/white-matter interface in the cortex and in hippocampal layers. DiTSI maps also unmasked small fascicles in the brain stem that were not detectable by SDE techniques and provided selective contrast across the major fiber pathways. Results also revealed prominent reductions of SA and RA in tissue with Alzheimer's disease pathology that were not observed for any other framework.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>New contrasts were evident for DiTSI framework metrics over a range of tissue environments with promise toward providing novel markers of pathology.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 6","pages":"2370-2385"},"PeriodicalIF":3.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30463","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542462","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":"Optimized navigator-based correction of breathing-induced B0 field fluctuations in multi-echo gradient-echo imaging of the spinal cord","authors":"Laura Beghini,&nbsp;Silvan Büeler,&nbsp;Martina D. Liechti,&nbsp;Alexander Jaffray,&nbsp;Gergely David,&nbsp;S. Johanna Vannesjo","doi":"10.1002/mrm.30475","DOIUrl":"10.1002/mrm.30475","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Multi-echo gradient-echo (ME-GRE) imaging in the spinal cord is susceptible to breathing-induced <i>B</i>₀ field fluctuations due to the proximity of the lungs, leading to ghosting artifacts. A navigator readout can be used to monitor the fluctuations; however, standard navigator processing often fails in the spinal cord. Here, we introduce navigator processing tailored specifically for spinal cord imaging.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>ME-GRE data covering all spinal cord regions were acquired in six healthy volunteers during free breathing at 3T. Centerline navigator readouts and respiratory belt recordings were collected during the acquisitions. The navigator processing included a Fast Fourier Transform and subsequent interval selection targeting the spinal cord, as well as SNR-weighted averaging over samples and coils on the complex data. Furthermore, a phase unwrapping algorithm making use of the belt recordings was developed. Imaging data were corrected by phase demodulation before image reconstruction.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p><i>B</i>₀ field fluctuations and ghosting artifacts were largest in the lower cervical and upper lumbosacral cord (˜5 Hz std), close to the edges of the lungs. Image reconstruction based on optimized navigator correction improved visual image quality and quantitative metrics (SNR, contrast-to-noise ratio (CNR), ghosting) in all regions of the spinal cord. The improvement was largest in regions with large field fluctuations (group-averaged increase in SNR/CNR of up to 29%/37% in single-echo images).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Optimized navigator-based correction can reduce ghosting artifacts and increase SNR/CNR in anatomical ME-GRE of the spinal cord. The enhanced image quality and ease of implementation across sites makes the technique attractive for clinical and scientific applications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"94 1","pages":"215-230"},"PeriodicalIF":3.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542468","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}