Magnetic Resonance in Medicine最新文献

{"title":"MRI detects tubulointerstitial changes in mouse models of radiation-induced nephropathy.","authors":"Julia Stabinska, Joe Piccolo, Anupriya Chhabra, Ioanna Liatsou, Kathy Gabrielson, Zhi Li, Zinia Mohanta, Farzad Sedaghat, Robert F Hobbs, George Sgouros, Michael T McMahon","doi":"10.1002/mrm.30443","DOIUrl":"https://doi.org/10.1002/mrm.30443","url":null,"abstract":"<p><strong>Purpose: </strong>We hypothesized that radiation-induced tubulointerstitial changes in the kidney can be assessed using MRI-based T₂ relaxation time measurements.</p><p><strong>Methods: </strong>We performed MRI, histology, and serum biochemistry in two mouse models of radiation nephropathy: one involving external beam radiotherapy and the other using internal irradiation with an α-particle-emitting actinium-225 radiolabeled antibody. We compared the mean T₂ values of different renal compartments between control and external beam radiotherapy or α-particle-emitting actinium-225 radiolabeled antibody-treated groups and between the two radiation-treated groups using a Wilcoxon rank-sum test.</p><p><strong>Results: </strong>Significantly higher T₂ values were found in the cortex and outer stripe of the outer medulla in all treated animals compared with the control group (p < 0.05). In addition, these changes in T₂ were observed before any changes in serum parameters, animal body weight, and kidney volume occurred.</p><p><strong>Conclusion: </strong>T₂ mapping is sensitive to radiation-induced tubulointerstitial changes in the kidney.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143024031","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":"Generalizable, sequence-invariant deep learning image reconstruction for subspace-constrained quantitative MRI.","authors":"Zheyuan Hu, Zihao Chen, Tianle Cao, Hsu-Lei Lee, Yibin Xie, Debiao Li, Anthony G Christodoulou","doi":"10.1002/mrm.30433","DOIUrl":"10.1002/mrm.30433","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a deep subspace learning network that can function across different pulse sequences.</p><p><strong>Methods: </strong>A contrast-invariant component-by-component (CBC) network structure was developed and compared against previously reported spatiotemporal multicomponent (MC) structure for reconstructing MR Multitasking images. A total of 130, 167, and 16 subjects were imaged using T₁, T₁-T₂, and T₁-T₂- <math> <semantics> <mrow><msubsup><mi>T</mi> <mn>2</mn> <mo>*</mo></msubsup> </mrow> <annotation>$$ {mathrm{T}}_2^{ast } $$</annotation></semantics> </math> -fat fraction (FF) mapping sequences, respectively. We compared CBC and MC networks in matched-sequence experiments (same sequence for training and testing), then examined their cross-sequence performance and generalizability by unmatched-sequence experiments (different sequences for training and testing). A \"universal\" CBC network was also evaluated using mixed-sequence training (combining data from all three sequences). Evaluation metrics included image normalized root mean squared error and Bland-Altman analyses of end-diastolic maps, both versus iteratively reconstructed references.</p><p><strong>Results: </strong>The proposed CBC showed significantly better normalized root mean squared error than MC in both matched-sequence and unmatched-sequence experiments (p < 0.001), fewer structural details in quantitative error maps, and tighter limits of agreement. CBC was more generalizable than MC (smaller performance loss; p = 0.006 in T₁ and p < 0.001 in T₁-T₂ from matched-sequence testing to unmatched-sequence testing) and additionally allowed training of a single universal network to reconstruct images from any of the three pulse sequences. The mixed-sequence CBC network performed similarly to matched-sequence CBC in T₁ (p = 0.178) and T₁-T₂ (p = 0121), where training data were plentiful, and performed better in T₁-T₂- <math> <semantics> <mrow><msubsup><mi>T</mi> <mn>2</mn> <mo>*</mo></msubsup> </mrow> <annotation>$$ {mathrm{T}}_2^{ast } $$</annotation></semantics> </math> -FF (p < 0.001) where training data were scarce.</p><p><strong>Conclusion: </strong>Contrast-invariant learning of spatial features rather than spatiotemporal features improves performance and generalizability, addresses data scarcity, and offers a pathway to universal supervised deep subspace learning.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007906","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":"CESTsimu: An open-source GUI for spectral and spatial CEST simulation.","authors":"Huabin Zhang, Bensheng Qiu, Jiadi Xu, Kannie Wy Chan, Jianpan Huang","doi":"10.1002/mrm.30430","DOIUrl":"https://doi.org/10.1002/mrm.30430","url":null,"abstract":"<p><strong>Purpose: </strong>The aim of this study was to create a user-friendly CEST simulation tool with a GUI for both spectral (1D Z-spectra) and spatial (2D phantom) CEST experiments, making the CEST simulation easier to perform.</p><p><strong>Methods: </strong>CESTsimu was developed using MATLAB App Designer. It consists of three modules: Saturation Settings, Exchange Settings, and Phantom Settings. CESTsimu can not only import/export files in the defined format but can also import files generated by other existing simulation platforms (e.g. pulseq-CEST).</p><p><strong>Results: </strong>The 1D Z-spectrum simulation results demonstrated the effectiveness of CESTsimu in simulating Z-spectra under various saturation ( <math> <semantics> <mrow> <msub><mrow><mi>B</mi></mrow> <mrow><mn>0</mn></mrow> </msub> </mrow> <annotation>$$ {mathrm{B}}_0 $$</annotation></semantics> </math> and <math> <semantics> <mrow> <msub><mrow><mi>B</mi></mrow> <mrow><mn>1</mn></mrow> </msub> </mrow> <annotation>$$ {mathrm{B}}_1 $$</annotation></semantics> </math> ) and exchange settings (concentration and exchange rate). The 2D simulation results showed that CESTsimu can generate an arbitrary number of phantoms with different shapes under different noise conditions. Notably, CESTsimu could also simulate <math> <semantics> <mrow> <msub><mrow><mi>B</mi></mrow> <mrow><mn>0</mn></mrow> </msub> </mrow> <annotation>$$ {mathrm{B}}_0 $$</annotation></semantics> </math> and <math> <semantics> <mrow> <msub><mrow><mi>B</mi></mrow> <mrow><mn>1</mn></mrow> </msub> </mrow> <annotation>$$ {mathrm{B}}_1 $$</annotation></semantics> </math> inhomogeneity in 2D patterns that mimicked practical conditions. Moreover, the accuracy of CESTsimu was validated by simulating 8 cases in the BMsim challenge.</p><p><strong>Conclusion: </strong>We developed a user-friendly CESTsimu GUI for intuitively simulating CEST experiments under diverse saturation and exchange settings in 1D and 2D conditions. CESTsimu has the potential to facilitate the broad utilization of CEST MRI among a wide range of users.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007895","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":"In vivo simultaneous proton resonance frequency shift thermometry and single reference variable flip angle T1 measurements","authors":"Nicholas Richards,&nbsp;Michael Malmberg,&nbsp;Henrik Odéen,&nbsp;Sara Johnson,&nbsp;Michelle Kline,&nbsp;Robb Merrill,&nbsp;Rock Hadley,&nbsp;Dennis L. Parker,&nbsp;Allison Payne","doi":"10.1002/mrm.30413","DOIUrl":"10.1002/mrm.30413","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>The single reference variable flip angle sequence with a multi-echo stack of stars acquisition (SR-VFA-SoS) simultaneously measures temperature change using proton resonance frequency (PRF) shift and T₁-based thermometry methods. This work evaluates SR-VFA-SoS thermometry in MR-guided focused ultrasound in an in vivo rabbit model.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Simultaneous PRF shift thermometry and T₁-based thermometry were obtained in a New Zealand white rabbit model (<i>n</i> = 7) during MR-guided focused ultrasound surgery using the SR-VFA-SoS sequence at 3 T. Distinct locations in muscle (<i>n</i> = 16), fat (<i>n</i> = 12), or the interface of both tissues (<i>n</i> = 23) were heated. The T₁-temperature coefficient of fat was determined using least-squares fitting of inversion recovery-based T₁ maps of untreated fat harvested from the animal and was applied to the in vivo measured heat-induced T₁ changes to create temperature maps.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Using k-space weighted image contrast reconstruction, temporal resolution of 1.71 s was achieved for simultaneous thermometry at 1.5 × 1.5 × 2 mm voxel resolution. PRF shift thermometry was not sensitive to heating in fat. T₁ changes were observed in fat at the ultrasound focus. The mean T₁-temperature coefficient for fat was determined to be 1.9%/°C ± 0.2%/°C. Precision was 0.76°C ± 0.18°C for PRF shift thermometry in muscle and 1.93°C ± 0.60°C for T₁-based thermometry in fat. Sonications in muscle showed an increase in T₁ of 2.4%/°C ± 0.9%/°C.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The SR-VFA-SoS sequence was shown to simultaneously measure temperature change using PRF shift and T₁-based methods in an in vivo model, providing thermometry for both aqueous and fat tissues.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 5","pages":"2070-2085"},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30413","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007907","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":"Learning-based motion artifact correction in the Z-spectral domain for chemical exchange saturation transfer MRI.","authors":"Munendra Singh, Sultan Z Mahmud, Vivek Yedavalli, Jinyuan Zhou, David Olayinka Kamson, Peter van Zijl, Hye-Young Heo","doi":"10.1002/mrm.30440","DOIUrl":"10.1002/mrm.30440","url":null,"abstract":"<p><strong>Purpose: </strong>To develop and evaluate a physics-driven, saturation contrast-aware, deep-learning-based framework for motion artifact correction in CEST MRI.</p><p><strong>Methods: </strong>A neural network was designed to correct motion artifacts directly from a Z-spectrum frequency (Ω) domain rather than an image spatial domain. Motion artifacts were simulated by modeling 3D rigid-body motion and readout-related motion during k-space sampling. A saturation-contrast-specific loss function was added to preserve amide proton transfer (APT) contrast, as well as enforce image alignment between motion-corrected and ground-truth images. The proposed neural network was evaluated on simulation data and demonstrated in healthy volunteers and brain tumor patients.</p><p><strong>Results: </strong>The experimental results showed the effectiveness of motion artifact correction in the Z-spectrum frequency domain (MOCO_Ω) compared to in the image spatial domain. In addition, a temporal convolution applied to a dynamic saturation image series was able to leverage motion artifacts to improve reconstruction results as a denoising process. The MOCO_Ω outperformed existing techniques for motion correction in terms of image quality and computational efficiency. At 3 T, human experiments showed that the root mean squared error (RMSE) of APT images decreased from 4.7% to 2.1% at 1 μT and from 6.2% to 3.5% at 1.5 μT in case of \"moderate\" motion and from 8.7% to 2.8% at 1 μT and from 12.7% to 4.5% at 1.5 μT in case of \"severe\" motion, after motion artifact correction.</p><p><strong>Conclusion: </strong>The MOCO_Ω could effectively correct motion artifacts in CEST MRI without compromising saturation transfer contrast.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007911","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":"Phantom-based gradient waveform measurements with compensated variable-prephasing: Description and application to EPI at 7 T","authors":"Hannah Scholten,&nbsp;Tobias Wech,&nbsp;Istvan Homolya,&nbsp;Herbert Köstler","doi":"10.1002/mrm.30425","DOIUrl":"10.1002/mrm.30425","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Introducing compensated variable-prephasing (CVP), a phantom-based method for gradient waveform measurements. The technique is based on the variable-prephasing (VP) method, but takes into account the effects of all gradients involved in the measurement.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We conducted measurements of a trapezoidal test gradient and of an EPI readout gradient train with three approaches: VP, CVP, and fully compensated variable-prephasing (FCVP). We compared them to one another and to predictions based on the gradient system transfer function. Furthermore, we used the measured and predicted EPI gradients for trajectory corrections in phantom images on a 7 T scanner.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The VP gradient measurements are confounded by lingering oscillations of the prephasing gradients, which are compensated in the CVP and FCVP measurements. FCVP is vulnerable to a sign asymmetry in the gradient chain. However, the trajectories determined by all three methods resulted in comparably high EPI image quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>We present a new approach allowing for phantom-based gradient waveform measurements with high precision, which can be useful for trajectory corrections in non-Cartesian or single-shot imaging techniques. In our experimental setup, the proposed “compensated variable-prephasing” method provided the most reliable gradient measurements of the different techniques we compared.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 5","pages":"2209-2223"},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrm.30425","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007913","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":"The proton resonance enhancement for CEST imaging and shift exchange (PRECISE) family of RF pulse shapes for CEST MRI","authors":"Zinia Mohanta,&nbsp;Julia Stabinska,&nbsp;Assaf A. Gilad,&nbsp;Peter B. Barker,&nbsp;Michael T. McMahon","doi":"10.1002/mrm.30410","DOIUrl":"10.1002/mrm.30410","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To optimize a 100 ms pulse for producing CEST MRI contrast and evaluate in mice.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A gradient ascent algorithm was employed to generate a family of 100 point, 100 ms pulses for use in CEST pulse trains (proton resonance enhancement for CEST imaging and shift exchange). Gradient ascent optimizations were performed for exchange rates = 500, 1500, 2500, 3500, and 4500 s⁻¹; and labile proton offsets (Δω) = 9.6, 7.8, 4.2, and 2.0 ppm. Seven proton resonance enhancement for CEST imaging and shift exchange pulse shapes were tested on an 11.7 T scanner using a phantom containing three representative CEST agents with peak saturation B_1,peak = 4 μT. The pulse producing the most contrast in phantoms was then evaluated for CEST MRI pH mapping of the kidneys in healthy mice after iopamidol administration.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The most promising pulse in terms of contrast performance across all three phantoms was the 9.6 ppm, 2500 s⁻¹ optimized pulse with ˜2.7 × increase in asymmetric magnetization transfer ratio (MTR_asym) over Gaussian, and ˜ 1.3 times over Fermi pulses for the same B_1,peak = 4 μT. This pulse also displayed a large improvement in contrast over the Gaussian pulse after administration of iopamidol in live mice.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>A new 100-ms pulse was developed based on gradient ascent optimizations, which produced better contrast compared to standard Gaussian and Fermi pulses in phantoms. This shape also showed a substantial improvement for CEST MRI pH mapping in live mice over the Gaussian shape and appears promising for a wide range of CEST applications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 5","pages":"1954-1968"},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced detection of glutamate via transverse relaxation encoding with narrowband decoupling in the human brain.","authors":"Li An, Sungtak Hong, Tara Turon, Adriana Pavletic, Christopher S Johnson, John A Derbyshire, Jun Shen","doi":"10.1002/mrm.30431","DOIUrl":"https://doi.org/10.1002/mrm.30431","url":null,"abstract":"<p><strong>Purpose: </strong>This study aims to improve the detection of glutamate (Glu) concentration and T₂ using an enhanced transverse relaxation encoding with narrowband decoupling (TREND) technique.</p><p><strong>Methods: </strong>A new editing pulse was designed to simultaneously invert both Glu H3 spins (2.12 ppm and 2.05 ppm) while minimizing the excitation of Glu H4. Additionally, a frequency band was created to invert the lactate (Lac) H2 spin (4.10 ppm) while saturating the NAA aspartyl H2 spin (4.38 ppm). Numerical simulations compared Glu and Lac signals using the original and new editing pulses. In vivo experiments were conducted on healthy participants at 7 T to validate this enhanced TREND technique.</p><p><strong>Results: </strong>Numerical simulations showed prominently enhanced Glu and Lac resonance signals with the new editing pulse. In vivo spectra showed a 47% ± 14% increase in Glu/Cr peak amplitude ratios with the new editing pulse. Using the enhanced TREND sequence, Glu/Cr concentration ratios in the anterior cingulate cortex were 1.03 ± 0.07 with Cramer-Rao lower bounds (CRLBs) of 1.1% ± 0.1%, and Glu T₂ values were 179 ± 18 ms with CRLBs of 1.2% ± 0.1%. The Lac/Cr concentration ratios in the same voxels were 0.05 ± 0.01 with CRLBs of 26% ± 14%, and Lac T₂ values were 196 ± 23 ms with CRLBs of 22% ± 15%.</p><p><strong>Conclusion: </strong>The new editing pulse significantly enhanced the detection of Glu and enabled the detection of Lac using TREND for measuring both the concentration and T₂ of the markers of oxidative metabolism and glycolysis.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007902","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":"Composite spin probes with adjustable oxygen sensitivity for pulse electron paramagnetic resonance imaging","authors":"Irene Canavesi,&nbsp;Navin Viswakarma,&nbsp;Raman Khurana,&nbsp;Boris Epel,&nbsp;Periannan Kuppusamy,&nbsp;Mark David Pagel,&nbsp;Mrignayani Kotecha","doi":"10.1002/mrm.30418","DOIUrl":"10.1002/mrm.30418","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Solid crystalline spin probes, such as lithium phthalocyanine (LiPc) and lithium octa-n-butoxynaphthalocyanine (LiNc-BuO), allow repeated oxygen measurement using electron paramagnetic resonance (EPR). Due to their short relaxation times, their use for pulse EPR oxygen imaging is limited. In this study, we developed and tested a new class of solid composite spin probes that modified the relaxation rates R₁ and R₂ of LiPc or LiNc-BuO probes, which allowed pO₂ measurements in the full dynamic (0–760 torr) range.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The composite probes were developed by embedding LiPc or LiNc-BuO with bonewax, beeswax, or petroleum jelly. All experiments were performed using a 25-mT EPR imager, JIVA-25®. A selected composite probe, LiPc-BW5 (LiPc + 5-times bonewax), was tested for its in vivo stability and robustness using oxygen-enhanced EPR oxygen imaging. As another application, a LiPc-BW5-based marker was tested to outline the SCC7 tumor in a C3H mouse.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The composite probes showed an increased oxygen measurement range compared with unaltered probes. The in vivo experiments with LiPc-BW5 showed the stability of the probes for repeated oxygen imaging up to 4 weeks of measurements. The in vivo pO₂ at the subcutaneous site changed from 26.1 ± 1.9 torr to 118.9 ± 1.9 torr when the breathing gas was changed from 21% O₂ to 100% O₂. The use of LiPc-BW5 as a fiducial marker showed its use in outlining the tumor boundaries.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>We developed a new class of robust and versatile solid composite probes with adjustable oxygen sensitivity that allows pO₂ imaging in the broad dynamic range.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 5","pages":"2239-2249"},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007899","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":"Three-dimensional whole-body imaging of the bioreduction and clearance of nitroxide probes in the thoracic and abdominal regions of mice using a compact and mobile electron paramagnetic resonance imager.","authors":"Hideo Sato-Akaba, Miho C Emoto, Hirotada G Fujii","doi":"10.1002/mrm.30432","DOIUrl":"https://doi.org/10.1002/mrm.30432","url":null,"abstract":"<p><strong>Purpose: </strong>Redox homeostasis plays a key role in regulating the overall health and development of organisms. This study aimed to develop a compact and mobile continuous-wave (CW) electron paramagnetic resonance (EPR) imager to facilitate stable, highly sensitive fast three-dimensional (3D) whole-body imaging of nitroxide-infused mice.</p><p><strong>Methods: </strong>A multiturn loop gap resonator with a diameter of 30 mm and length of 35 mm was designed for whole-body EPR imaging. A compact and mobile CW-EPR imager operating at 750 MHz was developed using this resonator. The automatic matching and tuning control systems were also adjusted to compensate for perturbations caused by the movement of the mice.</p><p><strong>Results: </strong>When the mice were inserted into the resonator, the resonant frequency was easily determined for all parts of the mouse, from the head to the lower abdomen. 3D EPR images of the mouse body from the thoracic region to the lower abdomen were obtained following infusion of a nitroxide, 3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (CxP). The EPR images clearly visualized the CxP distribution in various organs at different concentrations. Time-dependent EPR images also revealed that the signal intensities of the CxP decayed over time, and the decay rates for the heart, liver, and kidneys were evaluated.</p><p><strong>Conclusion: </strong>A compact and mobile EPR imager that enables 3D whole-body EPR image of nitroxide in mice was developed. The EPR imager exhibited long-term stability against motion effects caused by respiratory motion and heartbeats in mice. The EPR images clearly visualized the in vivo distribution, clearance, and metabolism of the nitroxide in organs.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143007922","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}