Magnetic Resonance in Medicine最新文献

{"title":"Simultaneous quantification of PCr, Cr, and pH in muscle CEST-MRI.","authors":"Yi Wang, Caiwen Yan, Xinhong Feng, Nan Gao, Jia-Hong Gao, Xiaolei Song","doi":"10.1002/mrm.30508","DOIUrl":"https://doi.org/10.1002/mrm.30508","url":null,"abstract":"<p><strong>Purpose: </strong>CEST-MRI allows sensitive in vivo detection of PCr and Cr in muscle. However, the accurate quantification is difficult due to overlapped \"peaks\" from multiple solutes and mixed contributions from fractional concentration ( <math> <semantics> <mrow><msub><mi>f</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {f}_{mathrm{b}} $$</annotation></semantics> </math> ) and exchange rate ( <math> <semantics> <mrow><msub><mi>k</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {k}_{mathrm{b}} $$</annotation></semantics> </math> ). This study aims to achieve simultaneous and accurate mapping of PCr, Cr, and pH in muscle.</p><p><strong>Methods: </strong>A two-step quantification method was proposed, by considering the co-existence of PCr and Cr in muscle and their dynamic transition. Firstly, exchangeable protons resonating at +2.6 ppm ( <math> <semantics> <mrow><msub><mi>PCr</mi> <mn>2.6</mn></msub> </mrow> <annotation>$$ {mathrm{PCr}}_{2.6} $$</annotation></semantics> </math> ) were quantified using our previous gQUCESOP. In the second gQUCESOP for resolving parameters at +1.9 ppm, we included both Cr's and another exchangeable guanidino proton of PCr resonating at +1.9 ppm ( <math> <semantics> <mrow><msub><mi>PCr</mi> <mn>1.9</mn></msub> </mrow> <annotation>$$ {mathrm{PCr}}_{1.9} $$</annotation></semantics> </math> ), with <math> <semantics> <mrow><msub><mi>f</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {f}_{mathrm{b}} $$</annotation></semantics> </math> and <math> <semantics> <mrow><msub><mi>k</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {k}_{mathrm{b}} $$</annotation></semantics> </math> for <math> <semantics> <mrow><msub><mi>PCr</mi> <mn>1.9</mn></msub> </mrow> <annotation>$$ {mathrm{PCr}}_{1.9} $$</annotation></semantics> </math> estimated from <math> <semantics> <mrow><msub><mi>PCr</mi> <mn>2.6</mn></msub> </mrow> <annotation>$$ {mathrm{PCr}}_{2.6} $$</annotation></semantics> </math> estimation in the first step. The method was validated by simulation and phantom study. In vivo rat experiments were performed at 9.4T, with pH measured also by <sup>31</sup>P-MRS.</p><p><strong>Results: </strong>Simulation suggested an over-estimated <math> <semantics> <mrow><msub><mi>f</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {f}_{mathrm{b}} $$</annotation></semantics> </math> and an under-estimated <math> <semantics> <mrow><msub><mi>k</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {k}_{mathrm{b}} $$</annotation></semantics> </math> of Cr if including a non-neglectable content of PCr. For a phantom with mixed PCr and Cr, the proposed method allowed accurate calculation of both concentrations and pH. For in vivo rat scans performed before and right after euthanasia, our methods achieved coincided <math> <semantics> <mrow><msub><mi>f</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {f}_{mathrm{b}} $$</annotation></semantics> </math> and <math> <semantics> <mrow><msub><mi>k</mi> <mi>b</mi></msub> </mrow> <annotation>$$ {k}_{mathrm{b}} $$</annotation","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143753405","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":"A correction for modeling radial, spiral, and PROPELLER dynamic contrast-enhanced data: Time-averaged extended Tofts.","authors":"Natalia V Korobova, Nienke P M Wassenaar, Marian A Troelstra, Eric M Schrauben, Oliver J Gurney-Champion","doi":"10.1002/mrm.30514","DOIUrl":"https://doi.org/10.1002/mrm.30514","url":null,"abstract":"<p><strong>Purpose: </strong>Dynamic contrast-enhanced sequences (e.g. spiral, radial, PROPELLER MRI) often rely on oversampling the center of k-space. Instead of the discrete snapshots obtained by Cartesian sampling, oversampling the k-space center results in time-averaging of the signal. We hypothesize that these time-averaged signals decrease the accuracy of pharmacokinetic modeling and propose a model that accounts for this effect.</p><p><strong>Theory and methods: </strong>To test our hypothesis, a modified extended Tofts model tailored to accommodate time-averaged signals is proposed. Simulated Monte Carlo experiments were conducted to compare the performance of the modified model with the conventional model. Additionally, to validate the findings in vivo, models were fitted to pseudo-spiral variable-density dynamic contrast-enhanced MRI scans of pancreatic cancer patients reconstructed at 4, 8, 10, and 15 s/frame.</p><p><strong>Results: </strong>The simulations demonstrated that for time-averaged acquisitions, our modified extended Tofts model provided more accurate and precise results than conventional models. Additionally, by integrating signals, some information on high temporal behavior was recovered. Particularly, at long acquisitions (15 s/frame), variable-density sampling with the modified model outperformed conventional discrete sampling. In vivo experiments confirmed these findings, as the corrected model showed more consistent estimates of parameters <math> <semantics> <mrow><msub><mi>v</mi> <mi>p</mi></msub> </mrow> <annotation>$$ {v}_p $$</annotation></semantics> </math> and <math> <semantics> <mrow><msub><mi>v</mi> <mi>e</mi></msub> </mrow> <annotation>$$ {v}_e $$</annotation></semantics> </math> over the tested sampling frequencies, highlighting its potential to improve accuracy in clinical settings.</p><p><strong>Conclusion: </strong>Our study demonstrates that time-averaged signals lead to decreased accuracy and precision in pharmacokinetic modeling when ignored. We suggest using our corrected pharmacokinetic model when performing dynamic contrast-enhanced with variable-density acquisitions, especially for dynamic scan times that are 8 s and longer.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143753385","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":"Flexible, high spatial and temporal resolution absolute thermometry of MRI phantoms using ethylene glycol.","authors":"Wesley Judd, Seong-Eun Kim, John Dzikiy, Dennis L Parker, Henrik Odéen","doi":"10.1002/mrm.30487","DOIUrl":"https://doi.org/10.1002/mrm.30487","url":null,"abstract":"<p><strong>Purpose: </strong>Quantitative MRI (qMRI) parameters such as relaxation rates and diffusion parameters are typically temperature dependent. Therefore, using phantoms to evaluate the accuracy of qMRI pulse sequences requires accurate knowledge of the absolute temperature throughout the phantom. This work aims to evaluate the use of ethylene glycol (EG) together with a multi-echo gradient recalled echo (ME-GRE) pulse sequence for MR spectroscopic-based measurement of absolute temperature in phantoms.</p><p><strong>Methods: </strong>We develop and test a simple MR spectroscopic imaging approach to rapidly, automatically, accurately, and precisely measure absolute temperature at multiple locations throughout a qMRI phantom. A series of EG cubes are located throughout the phantom and imaged with a ME-GRE pulse sequence over a wide range of temperatures (˜7°C-37°C) and on multiple scanners. The resulting images were automatically processed to isolate the EG. The measured spectral peak spacing was calibrated to temperature using fiber optic probes. The accuracy and precision of the measurements were evaluated between scanners over a range of temperatures.</p><p><strong>Results: </strong>The spectral peak spacing of EG can be used to predict temperature with an error of 0.6°C ± 0.3°C with an increase of 0.1°C when evaluated on different scanners. An automatic reconstruction approach without manual input is described, highlighting the feasibility of online implementation on a clinical MRI scanner.</p><p><strong>Conclusion: </strong>The described MR spectroscopic imaging approach is easy to implement and provides robust, automatic, and accurate measurement of absolute temperature throughout a phantom.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143753364","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":"A shielded 32-channel body transceiver array with integrated electronics for 7 T.","authors":"Tobey D Haluptzok, Russell L Lagore, Simon Schmidt, Gregory J Metzger","doi":"10.1002/mrm.30498","DOIUrl":"https://doi.org/10.1002/mrm.30498","url":null,"abstract":"<p><strong>Purpose: </strong>Develop a 32-channel transceiver array for 7 T body imaging that incorporates an RF shield, improves SNR, lowers g-factors, and is robust to external loading.</p><p><strong>Methods: </strong>The addition of a local RF shield was first investigated for single resonant blocks consisting of either one loop and a dipole (LD) or three loops and a dipole (3LD). A 32-channel array consisting of eight shielded 3LD blocks (32LD-SH) was constructed and validated for in-vivo use. The SNR, parallel imaging, and transmit performance were compared to a previously published 16-channel LD array (16LD). The effect of top loading was investigated by placing arms on top of the coils and measuring S-parameter changes. In vivo imaging of multiple anatomies was performed.</p><p><strong>Results: </strong>In single block experiments, the RF shield impacted SNR and <math> <semantics> <mrow><msubsup><mi>B</mi> <mn>1</mn> <mo>+</mo></msubsup> </mrow> <annotation>$$ {mathrm{B}}_1^{+} $$</annotation></semantics> </math> performance by <5%. The 3LD blocks had 80% higher peripheral SNR and 25% higher SNR at a depth of 10 cm. The 32LD-SH array had 18% lower <math> <semantics> <mrow><msubsup><mi>B</mi> <mn>1</mn> <mo>+</mo></msubsup> </mrow> <annotation>$$ {B}_1^{+} $$</annotation></semantics> </math> /W^0.5 efficiency and 30% higher central SNR compared to the 16LD array and supported threefold acceleration in the foot-head direction. Arm placement had no effect on the 32LD-SH array but reduced the 16LD match to 5.4 dB.</p><p><strong>Conclusion: </strong>A 32-channel transceiver array was developed for 7 T body imaging that is insensitive to top loading and has higher SNR and lower g-factors compared to an existing 16-channel transceiver array. Despite lower transmit performance, parallel transmit optimization permitted the 32LD-SH to achieve flip angles necessary for high-quality gradient and spin echo acquisitions of target organs in the chest, abdomen, and pelvis.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143753390","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":"Monitoring the head exposure of MRI workers around 3 T, 7 T, and 11.7 T scanners using smart goggles equipped with a network of magnetometers.","authors":"Hugo Nicolas, Corentin Féry, Thomas Quirin, Nicolas Weber, Julien Oster, Jacques Felblinger, Alexandre Vignaud, Joris Pascal","doi":"10.1002/mrm.30513","DOIUrl":"https://doi.org/10.1002/mrm.30513","url":null,"abstract":"<p><strong>Purpose: </strong>The aim of this paper is to introduce a new magnetic field exposimeter device that consists of goggles equipped with magnetic sensors for the assessment of the field exposure of MRI workers' heads. This is not possible with conventional pocket exposimeters. Hence, this device allows head-level field exposure to be measured, which can induce physiological effects on MRI workers, and which are required to be covered by managing the laboratory-related safety hazards directive 2013/35/EU.</p><p><strong>Methods: </strong>Using on-chip monolithic three-axis Hall effect magnetometers, recently introduced on the market, we developed an exposimeter with unprecedented accuracy, which allows the measurement of the magnetic field closed to the organs which are the most impacted by strong magnetic fields: the brain, the eyes, and the tongue.</p><p><strong>Results: </strong>The exposimeter prototypes were successfully tested around 3 T, 7 T, and 11.7 T MRI scanners on different workers and volunteers in real conditions. Comparisons with chest-level measurements lead typically to lower values than exposure recorded at the head-level, confirming the need for such head-level assessments. Exposure of the head above the limits established by the directive was also recorded (>2 T or >2.7 T/s).</p><p><strong>Conclusion: </strong>This new exposimeter allows for a more accurate assessment of field exposure of MRI workers. Further improvements in the miniaturization and the usability of the exposimeter will allow us to disseminate the device and open the way to a larger-scale study.</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":"143730279","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":"Imaging near titanium total hip arthroplasty at 0.55 T compared with 3 T.","authors":"Kübra Keskin, Sophia X Cui, Bochao Li, Jordan S Gross, Jay Acharya, Zorica Buser, Jay R Lieberman, Brian A Hargreaves, Krishna S Nayak","doi":"10.1002/mrm.30438","DOIUrl":"https://doi.org/10.1002/mrm.30438","url":null,"abstract":"<p><strong>Purpose: </strong>To compare 0.55 T and 3 T MRI for imaging patients with titanium total hip arthroplasty (THA). Patients with orthopedic metallic implants often require diagnostic imaging to evaluate adjacent tissues. MRI performance measures, including artifact levels and SNR, vary with field strength.</p><p><strong>Methods: </strong>Six patients with titanium THA were scanned with similar protocols at 0.55 T and 3 T, including proton density (PD) weighted turbo spin echo (TSE), PD TSE with view-angle tilting (TSE + VAT), PD slice encoding for metal artifact correction (SEMAC), and short tau inversion recovery with SEMAC (STIR-SEMAC). Images from both field strengths were scored by two readers and qualitatively and quantitatively compared.</p><p><strong>Results: </strong>Diagnostic confidence was significantly higher at 0.55 T compared to 3 T. Perceived metal artifact was substantially reduced at 0.55 T compared to 3 T. At 0.55 T, diagnostic imaging was achieved both without and with multi spectral imaging (MSI) for PD weighted images.</p><p><strong>Conclusion: </strong>Compared to 3 T, 0.55 T MRI offers substantially reduced metal artifacts and higher diagnostic confidence when imaging titanium THA. Advanced multi-spectral techniques may not be required when the metallic components are entirely titanium.</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":"143730277","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 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, Hsin-Jung Yang, Nader Binesh, Archana Vadiraj Malagi, Yun Shang, Li-Ting Huang, Jeremy Zepeda, Fardad Michael Serry, Debiao Li, Hui Han","doi":"10.1002/mrm.30474","DOIUrl":"https://doi.org/10.1002/mrm.30474","url":null,"abstract":"<p><strong>Purpose: </strong>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><p><strong>Methods: </strong>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><p><strong>Results: </strong>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><p><strong>Conclusion: </strong>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>","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":"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}