Magnetic Resonance in Medicine最新文献

{"title":"A theoretical interpretation of diffusion weighted and intravoxel incoherent motion imaging for cerebrospinal fluid flow.","authors":"Tomohiro Otani, Yoshitaka Bito, Shigeki Yamada, Yoshiyuki Watanabe, Shigeo Wada","doi":"10.1002/mrm.70062","DOIUrl":"https://doi.org/10.1002/mrm.70062","url":null,"abstract":"<p><strong>Purpose: </strong>Diffusion-weighted imaging (DWI) and intravoxel incoherent motion (IVIM) imaging are well-established approaches for evaluating cerebrospinal fluid (CSF) flow in subarachnoid and perivascular spaces, and have recently been applied to study ventricular CSF flow. However, DWI does not directly measure flow velocity, and the physical implications of DWI measurements are unclear. This study aimed to provide a theoretical interpretation of the DWI and IVIM imaging of CSF flow velocity fields.</p><p><strong>Theory: </strong>The general semi-analytical form of the signal attenuations caused by fluid flow and the resultant apparent diffusion coefficient were derived from the Bloch-Torrey equation for arbitrary <math> <semantics><mrow><mi>b</mi></mrow> <annotation>$$ b $$</annotation></semantics> </math> values.</p><p><strong>Methods: </strong>The fundamental properties of the signal attenuation in laminar flow velocity fields were investigated. A Monte Carlo simulation of the IVIM parameter estimation was performed based on these signal attenuations, taking background noise into consideration.</p><p><strong>Results: </strong>The developed theoretical framework indicates that signal attenuations in DWI detect intravoxel flow velocity standard deviations ranging from approximately 0.1 to 10 mm/s within the range of practical scan parameter settings. The lower bounds of the DWI flow profiles appeared where the flow effect was an order of magnitude lower than the molecular diffusion effects, even when <math> <semantics><mrow><mi>b</mi></mrow> <annotation>$$ b $$</annotation></semantics> </math> increased. The IVIM fitting parameters reflected the flow effects of the signal attenuations despite an inconsistency with the original IVIM model assumptions.</p><p><strong>Conclusion: </strong>The physical implications of signal attenuation in DWI have been theoretically clarified. This framework provides a useful basis for understanding CSF flow dynamics and considering appropriate imaging settings.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145000950","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":"Rapid free-breathing myocardial T₁ mapping with free-running interleaved multi-slice acquisition and respiratory motion correction using self-navigated auto calibration.","authors":"Hongzhang Huang, Zijian Zhou, Zhenfeng Lyu, Qinfang Miao, Genqiang Chen, Peng Hu, Haikun Qi","doi":"10.1002/mrm.70071","DOIUrl":"https://doi.org/10.1002/mrm.70071","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;To develop a rapid 2D free-running myocardial &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; mapping technique that is robust to through-plane respiratory motion.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;A free-running golden angle radial sequence consisting of &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; encoding and self-navigated auto motion calibration (SNAC) was developed. The &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; encoding adopted inversion recovery (IR) prepared interleaved multi-slice acquisition with optimized inter-slice gap to ensure a uniform excitation of the middle slice regardless of through-plane respiratory motion. The flip angles were alternated between the odd and even IR readouts to correct flip-angle errors. SNAC was designed to calibrate the through-plane motion with the respiratory self-navigation signal extracted from the free-running sequence, and integrate the multi-slice data into a through-plane motion-corrected 2D slice for &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; mapping reconstruction. Numerical simulations were performed to optimize the key sequence parameters, followed by phantom and in-vivo imaging to validate the accuracy and repeatability.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Numerical simulations yielded the dual flip angles minimizing &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; estimation errors and the adjacent slice offset achieving uniformity in the superimposed slice profile. Phantom experiments demonstrated a strong correlation between the proposed and reference method, and no dependence of the free-running &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; estimation on heart rates. Adding through-plane respiratory motion correction significantly improved the in-vivo &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; mapping sharpness and visual quality. Validated against the conventional breath-hold mapping technique, the motion corrected free-running method achieved comparable &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {T}_1 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; mapping quality and repeatability.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;Respiratory motion is effectively suppressed in the p","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145000904","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":"Navigator motion-resolved MR fingerprinting using implicit neural representation: Feasibility for free-breathing three-dimensional whole-liver multiparametric mapping.","authors":"Chao Li, Jiahao Li, Jinwei Zhang, Eddy Solomon, Alexey V Dimov, Pascal Spincemaille, Thanh D Nguyen, Martin R Prince, Yi Wang","doi":"10.1002/mrm.70063","DOIUrl":"https://doi.org/10.1002/mrm.70063","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a multiparametric free-breathing three-dimensional, whole-liver quantitative maps of water T₁, water T₂, fat fraction (FF) and R₂*.</p><p><strong>Methods: </strong>A multi-echo 3D stack-of-spiral gradient-echo sequence with inversion recovery and T₂-prep magnetization preparations was implemented for multiparametric MRI. Fingerprinting and a neural network based on implicit neural representation (FINR) were developed to simultaneously reconstruct the motion deformation fields, the static images, perform water-fat separation, and generate T₁, T₂, R₂*, and FF maps. FINR performance was evaluated in 10 healthy subjects by comparison with quantitative maps generated using conventional breath-holding imaging.</p><p><strong>Results: </strong>FINR consistently generated sharp images in all subjects free of motion artifacts. FINR showed minimal bias and narrow 95% limits of agreement for T₁, T₂, R₂*, and FF values in the liver compared with conventional imaging. FINR training took about 3 h per subject, and FINR inference took less than 1 min to produce static images and motion deformation fields.</p><p><strong>Conclusions: </strong>FINR is a promising approach for 3D whole-liver T₁, T₂, R₂*, and FF mapping in a single free-breathing continuous scan.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959399","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":"MR-ARFI to evaluate intensity variability and enhance targeting of FUS: A brain study in rats.","authors":"Abubakr Eldirdiri, Linda Chang, David A Martin, Eric Cunningham, Segun Bernard, Donna J Calu, Kim Butts Pauly, Thomas Ernst","doi":"10.1002/mrm.70039","DOIUrl":"https://doi.org/10.1002/mrm.70039","url":null,"abstract":"<p><strong>Purpose: </strong>Inconsistencies in focused ultrasound (FUS) transducer positioning and skull-induced aberrations can reduce the targeting accuracy and cause inconsistencies in the intensity delivered during FUS neuromodulation procedures. This study aimed to evaluate the use of MR-acoustic radiation force imaging (MR-ARFI) in improving the targeting accuracy and assessing the variation in the pressure delivered during FUS procedures.</p><p><strong>Methods: </strong>An MR-guided FUS system was used to bilaterally target the nucleus accumbens region of Sprague-Dawley rats. Displacement maps were acquired with MR-ARFI to refine the targeting accuracy by adjusting the focal point position electronically and mechanically as necessary. In addition, the ARFI measurements were used to establish the relationship between the displacement and input power, and to assess intra- and inter-subject variability in FUS pressure.</p><p><strong>Results: </strong>ARFI displacement was a strong predictor of FUS power (r² = 0.935, p < 0.001), with displacements showing quadratic dependence on FUS pressure. Intra-site and intra-subject coefficients of variation in ARFI displacement measurements were 9.0% and 18.6%, whereas the variation across animals was 43.4%. Initial MR-guided targeting required secondary adjustments in 21% of cases.</p><p><strong>Conclusion: </strong>Despite initial MRI guidance, substantial targeting errors were observed, highlighting the need for advanced imaging techniques like MR-ARFI in neuromodulation procedures. Moreover, ARFI displacements in the target region across subjects varied over three-fold, indicating very high variation in the delivered acoustic pressure. By improving the precision of FUS targeting and estimating deviations in the FUS pressure, MR-ARFI can improve therapeutic outcomes and reduce risks in transcranial FUS neuromodulation.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959433","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 tagged MRI at 0.55 T.","authors":"Prakash Kumar, Krishna S Nayak","doi":"10.1002/mrm.70060","DOIUrl":"10.1002/mrm.70060","url":null,"abstract":"<p><strong>Purpose: </strong>To determine the feasibility of tagged MRI at 0.55 T and tag persistence for cardiac and speech production applications. This is particularly challenging due to the short muscle T₁ at 0.55 T (701 ms) and requires advanced techniques for maximizing initial tag contrast and signal-to-noise ratio (SNR)-efficient imaging.</p><p><strong>Methods: </strong>Tagged MRI was performed using phase-sensitive tagging (REALTAG) two-dimensional grid-based preparation and spiral balanced steady-state free precession (bSSFP) imaging. Experiments were performed in healthy adult volunteers using a 0.55 T MRI system with high-performance gradients on two functional anatomies. Cardiac scans had 7.5-mm tag spacing, 1.3-mm² in-plane resolution, and were acquired during about 18s breath-holds. Speech scans had 10-mm tag spacing, 2-mm² spatial resolution, and were acquired in real time. Resulting tagged images were compared with conventional gradient-recalled echo (GRE). Tag persistence and tag contrast-to-noise ratio were measured and compared.</p><p><strong>Results: </strong>REALTAG preparation and phase-sensitive reconstruction resulted in taglines that recover quickly when compared to 1.5 T, for both bSSFP and GRE imaging approaches. The bSSFP approach, at optimal flip angles, provided a 1.35-fold improved SNR and 1.6-fold improved tag persistence. For a tag contrast-to-noise ratio threshold of 6, the tag persistence was about 506 ms for GRE and about 851 ms for bSSFP.</p><p><strong>Conclusion: </strong>Tagged MRI is feasible at 0.55 T and can be used for functional analysis of muscle motion such as cardiac and speech applications, despite the short T₁. Spiral bSSFP along with REALTAG preparation pulses provide adequate SNR and contrast to visualize cardiac systolic mechanics and to visualize tongue deformation during short speech utterances.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959381","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":"mtrk-A flexible environment for developing open-source MRI pulse sequences.","authors":"Anais Artiges, Amanpreet Singh Saimbhi, Carlos Castillo-Passi, Riccardo Lattanzi, Kai Tobias Block","doi":"10.1002/mrm.70067","DOIUrl":"https://doi.org/10.1002/mrm.70067","url":null,"abstract":"<p><strong>Purpose: </strong>To introduce mtrk, a new open-source tool based on modern software-engineering principles that simplifies pulse-sequence design, implementation, and dissemination.</p><p><strong>Methods: </strong>The mtrk framework is vendor-agnostic and relies on a compact and human-readable descriptive language. Users can design pulse sequences using either a Python-based programming interface or an intuitive graphical interface. The graphical interface also allows for visualizing pulse-sequence diagrams. A driver sequence was developed to run mtrk sequences on MR scanners. A spin-echo sequence was designed with mtrk and converted to Pulseq for comparison. Both versions were compared to an equivalent vendor sequence in phantom and in vivo experiments.</p><p><strong>Results: </strong>Images from the mtrk and Pulseq versions were nearly identical and showed over 90% similarity compared to the vendor sequence, despite minor unavoidable design differences. Phantom images matched corresponding synthetic images simulated using the same pulse sequences.</p><p><strong>Conclusion: </strong>The mtrk framework simplifies the development of pulse sequences by providing an intuitive descriptive language and compatibility with the Pulseq format. Users can design and simulate pulse sequences using the graphical interface without any programming experience.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959476","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":"Accelerated water residual removal in MRS: Exploring deep learning versus fitting-based approaches.","authors":"Federico Turco, Johannes Slotboom, Milena Capiglioni","doi":"10.1002/mrm.70031","DOIUrl":"https://doi.org/10.1002/mrm.70031","url":null,"abstract":"<p><strong>Purpose: </strong>Removing water residual signals from MRS spectra is crucial for accurate metabolite quantification. However, currently available algorithms are computationally intensive and time-consuming, limiting their clinical applicability. This work aims to propose and validate two novel pipelines for fast water residual removal in MRS.</p><p><strong>Methods: </strong>Two methods for water residual removal are proposed and evaluated: DeepWatR and WaterFit. DeepWatR uses a U-Net-like architecture with an attention mechanism for skip connections. WaterFit uses Torch auto-differentiation to estimate parameters for a 7-pool Lorentzian model. The accuracy and time-efficiency of these methods were assessed using simulated and in vivo 1H brain datasets and compared with the gold standard, Hankel Lanczos singular value decomposition method (HLSVD)Pro.</p><p><strong>Results: </strong>In the simulated dataset, the average percentage quantification error was <math> <semantics> <mrow><mrow><mo>(</mo> <mrow><mn>8.54</mn> <mo>±</mo> <mn>17.49</mn></mrow> <mo>)</mo></mrow> </mrow> <annotation>$$ left(8.54pm 17.49right) $$</annotation></semantics> </math> % for DeepWatR and <math> <semantics> <mrow><mrow><mo>(</mo> <mrow><mn>7.86</mn> <mo>±</mo> <mn>16.69</mn></mrow> <mo>)</mo></mrow> </mrow> <annotation>$$ left(7.86pm 16.69right) $$</annotation></semantics> </math> % for WaterFit, both comparable to <math> <semantics> <mrow><mrow><mo>(</mo> <mrow><mn>7.68</mn> <mo>±</mo> <mn>15.6</mn></mrow> <mo>)</mo></mrow> </mrow> <annotation>$$ left(7.68pm 15.6right) $$</annotation></semantics> </math> % for HLSVDPro in the main metabolites (Cr, Cho, and NAA). DeepWatR was 51 times faster and WaterFit was 22.7 times faster than HLSVDPro for a dataset of 10 000 voxels when using a low-end graphics processing unit. For 100 voxels, the speed-up is 6.5 and 7.5 times faster for DeepWatR and WaterFit, respectively. WaterFit showed higher metabolite fitting accuracy after water removal compared to DeepWatR.</p><p><strong>Conclusion: </strong>WaterFit showed a superior balance of accuracy and processing speed in removing water residual from MRS data compared to DeepWatR. The proposed WaterFit implementation significantly reduces preprocessing time while maintaining metabolite fitting accuracy comparable to gold standard methods. This advancement addresses the need for efficient processing methods that can facilitate analysis and enhance the clinical utility of MRS.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959598","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":"Fabric on fabric: A conductive fabric-based wearable coil using cutting plotter for MRI at 3T.","authors":"Thejas Vishnu Ramesh, Sergio Martin-Moreno, Folk W Narongrit, Christopher J S Chang, Vitaliy L Rayz, Joseph V Rispoli","doi":"10.1002/mrm.70051","DOIUrl":"https://doi.org/10.1002/mrm.70051","url":null,"abstract":"<p><strong>Purpose: </strong>Wearable coils fabricated using conductive threads have high resistance that limits SNR. The purpose of this work is to demonstrate the utility of conductive fabric as a coil conductor that can be fabricated using a cutting plotter.</p><p><strong>Methods: </strong>A single-channel coil was developed by feeding a conductive fabric sheet into an automatic cutting plotter. The fabric coil was loaded on a spherical phantom to evaluate SNR and B₁ ⁺ homogeneity and compared with a single-channel conductive thread coil and a rigid printed circuit board (PCB) coil. A 14-channel wearable neck array was developed for structural imaging of the cervical spine and 4D flow MRI of the carotid arteries. The SNR from structural images and velocity-to-noise ratio (VNR) from flow images were compared with a 16-channel commercial coil.</p><p><strong>Results: </strong>The single-channel conductive fabric coil provided 6.7% and 125.9% SNR increase when compared to the rigid PCB and conductive thread coils across 10 scan repetitions. The B₁ ⁺ field homogeneity was 96.4%, 1% higher than the rigid PCB and conductive thread coils. The wearable neck array demonstrated a 51.1% average SNR increase from the cervical spine images across three volunteers and a 12.0% VNR increase from the postprocessed 4D flow data when compared with the commercial 16-channel array.</p><p><strong>Conclusion: </strong>The possibility of developing wearable coils using conductive fabric to enhance SNR in structural images and VNR in 4D flow images is demonstrated. The conductive fabric technique enables fabrication on commercial garments resulting in form-fitting wearable coils.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959189","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":"Optimized motion-insensitive PDFF mapping of the liver.","authors":"Jiayi Tang, Daiki Tamada, Raphael do Vale Souza, Aaron Faacks, Jitka Starekova, Julius F Heidenreich, Lukas Müller, Garrett C Fullerton, Collin J Buelo, Jeff Kammerman, Jean H Brittain, Scott B Reeder, Diego Hernando","doi":"10.1002/mrm.70047","DOIUrl":"10.1002/mrm.70047","url":null,"abstract":"<p><strong>Purpose: </strong>To implement, optimize, and validate parallel imaging (PI)-accelerated, 2D, flip angle modulated (FAM) chemical shift-encoded quantification of liver proton-density fat fraction (PDFF), with motion insensitivity.</p><p><strong>Methods: </strong>The optimization cost function that determines flip angles in FAM was generalized for PI. Phantom studies and prospective studies in volunteers with varying liver fat levels were performed. Free-breathing FAM was acquired in the axial, sagittal, and coronal planes, with varying nominal PI acceleration factors (R) of 1.0 to 3.0. A breath-held, commercially available 3D chemical shift-encoded method was acquired as reference for PDFF. Overall image quality, qualitative SNR, and motion artifacts for all methods were Likert-scale rated. PDFF measured by FAM was compared to reference to assess bias. Test-retest repeatability was assessed for all methods by repeating acquisitions after volunteer repositioning. Noise performance was assessed with standard deviation of PDFF maps as R increased.</p><p><strong>Results: </strong>The reader study (N = 3 readers/10 subjects) demonstrated excellent image quality for FAM during free-breathing, with reduced motion artifacts compared to breath-held reference (p < 0.01). PI-accelerated FAM shows fewer motion artifacts than unaccelerated FAM (p < 0.01). In all planes and accelerations, PDFF measured by FAM showed good agreement with reference PDFF measurements (mean bias: -0.4% to 2.0% PDFF; 95% limits of agreement: 2.8% to 4.0% PDFF). FAM in axial and coronal planes showed similar or improved repeatability (repeatability coefficient = 1.7% to 2.6% PDFF) compared to the reference (2.7%). Sagittal FAM shows similar or worse repeatability (repeatability coefficient = 3.0% to 3.6%). FAM with R = 2.0 has good noise performance and high SNR efficiency.</p><p><strong>Conclusion: </strong>FAM, in axial or coronal planes with R = 2.0, is optimal for motion-insensitive liver PDFF quantification.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12490877/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959397","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":"In vitro characterization of hemodynamics in bicuspid aortic valves: The impact of valve and ascending aortic morphologies.","authors":"Kaoru Hattori, Natsuki Nakama, Jumpei Takada, Michinobu Nagao, Yasuhiro Goto, Hiroshi Niinami, Kiyotaka Iwasaki","doi":"10.1002/mrm.70064","DOIUrl":"https://doi.org/10.1002/mrm.70064","url":null,"abstract":"<p><strong>Purpose: </strong>This study investigated the effect of bicuspid aortic valve (BAV) morphology and ascending aortic curvature (AAAc) bending angles on aortic hemodynamics, focusing on transvalvular jets and secondary helical flows that contribute to systolic hemodynamic stress linked to aortic complications.</p><p><strong>Methods: </strong>Using an MRI-compatible pulsatile flow and pressure system, 24 configurations involving six aortic valves (three Type 1 asymmetric BAVs, two Type 0 symmetric BAVs, and one tricuspid aortic valve [TAV]) across four ascending aortic morphologies-two diameters (30 mm and 40 mm) and two AAAc angles (130° and 109°)-were analyzed through four-dimensional-flow MRI measurements.</p><p><strong>Results: </strong>Three Type 1 BAVs displayed highly deviated transvalvular jets directed toward the aortic wall on the side of the nonfused cusp. Particularly, the right-noncoronary and left-noncoronary cusp fusion phenotypes exhibited markedly eccentric secondary helical flows, thereby increasing hemodynamic stress on the ascending aortic wall. A narrower AAAc further amplified these effects by elevating jet velocity and circulation. Conversely, Type 0 BAVs and TAV were suggested to have lower hemodynamic forces, characterized by less-deviated jets and reduced secondary helical flow eccentricity. Aortic dilation, while enhancing secondary flow circulation, appeared to reduce eccentricity, suggesting a compensatory mechanism in response to altered hemodynamics.</p><p><strong>Conclusion: </strong>The combination of the position of the nonfused cusp and AAAc emerges as a critical determinant of secondary helical flow eccentricity and circulation during peak-to-late systole. The risk assessment based on these hemodynamic parameters offers a novel strategy for identifying individuals at elevated risk of future aortic events.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144959283","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}