Magnetic Resonance in Medicine最新文献

{"title":"Whole heart perfusion with high-multiband Simultaneous Multislice Imaging via Linear phase modulated Extended field of view (SMILE).","authors":"Shen Zhao, Junyu Wang, Xitong Wang, Sizhuo Liu, Quan Chen, Kevin Kai Li, Yoo Jin Lee, Michael Salerno","doi":"10.1002/mrm.30541","DOIUrl":"https://doi.org/10.1002/mrm.30541","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a simultaneous multislice (SMS) first-pass perfusion technique that can achieve whole heart coverage with high multi-band factors, while avoiding the issue of slice leakage.</p><p><strong>Methods: </strong>The proposed Simultaneous Multislice Imaging via Linear phase modulated Extended field of view (SMILE) treats the SMS acquisition and reconstruction within an extended field of view framework, allowing arbitrarily under-sampling of phase encoding lines of the extended k-space matrix and enabling the direct application of 2D parallel imaging reconstruction techniques. We presented a theoretical framework that offers insights into the performance of SMILE. We performed retrospective comparison on 28 subjects and prospective perfusion experiments on 43 patients undergoing routine clinical CMR studies with SMILE at multiband (MB) factors of 3-5, with a net acceleration rate ( <math> <semantics><mrow><mi>R</mi></mrow> <annotation>$$ R $$</annotation></semantics> </math> ) of 8 and 10 respectively, and compared SMILE to conventional SMS techniques using standard FOV 2D CAIPI acquisition and standard 2D slice separation techniques including split-slice GRAPPA and ROCK-SPIRiT.</p><p><strong>Results: </strong>Retrospective studies demonstrated 5.2 to 8.0 dB improvement in signal to error ratio (SER) of SMILE over CAIPI perfusion. Prospective studies showed good image quality with grades of 4.1 <math> <semantics><mrow><mo>±</mo></mrow> <annotation>$$ pm $$</annotation></semantics> </math> 0.7 for MB = 3, <math> <semantics><mrow><mi>R</mi></mrow> <annotation>$$ R $$</annotation></semantics> </math> = 8 and 3.5 <math> <semantics><mrow><mo>±</mo></mrow> <annotation>$$ pm $$</annotation></semantics> </math> 1.0 for MB = 5, <math> <semantics><mrow><mi>R</mi></mrow> <annotation>$$ R $$</annotation></semantics> </math> = 10. (5-point Likert Scale).</p><p><strong>Conclusion: </strong>The theoretical derivation and experimental results validate the SMILE's improved performance at high acceleration and MB as compared to the existing 2D CAIPI SMS acquisition and reconstruction techniques for first-pass myocardial perfusion imaging.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144369046","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 abdominal sodium MRI combined with 32-channel proton pTx MRI at 7 Tesla in a large field-of-view.","authors":"Anna K Scheipers, Johannes A Grimm, Jana Losch, Stephan Orzada, Thomas M Fiedler, Armin M Nagel, Sebastian Schmitter, Mark E Ladd, Tanja Platt","doi":"10.1002/mrm.30605","DOIUrl":"https://doi.org/10.1002/mrm.30605","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;To combine large field-of-view abdominal &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^1mathrm{H} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and quantitative sodium ( &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;23&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mtext&gt;Na&lt;/mtext&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^{23}mathrm{Na} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) MRI in the same position at 7 T to enable the quantification of the tissue sodium concentration via &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;23&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mtext&gt;Na&lt;/mtext&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^{23}mathrm{Na} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; MRI and the anatomical assignment in &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^1mathrm{H} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; images without repositioning in several tissues and organs at once.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;A custom-built &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;23&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mtext&gt;Na&lt;/mtext&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^{23}mathrm{Na} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; birdcage coil and reference vial setup together with a 32-channel &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^1mathrm{H} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; pTx array were employed at 7 T to allow dual-nuclei MRI in the same position for a field-of-view (FOV) of &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;mn&gt;400&lt;/mn&gt; &lt;mo&gt;×&lt;/mo&gt; &lt;mn&gt;400&lt;/mn&gt; &lt;mo&gt;×&lt;/mo&gt; &lt;mn&gt;400&lt;/mn&gt; &lt;mo&gt;)&lt;/mo&gt; &lt;mspace&gt;&lt;/mspace&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mtext&gt;mm&lt;/mtext&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ left(400times 400times 400right)kern0.3em {mathrm{mm}}^3 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; . &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; relaxation effects in the reference vials and phantom were corrected, &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {B}_1^{+} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; maps were measured, and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;-&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {B}_1^{-} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; maps were simulated to correct the acquired &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;23&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;mtext&gt;Na&lt;/mtext&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ {}^{23}mathrm{Na} $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; data in post-processing. These corrections were evaluated in a phantom and then applied in vivo in three healthy volunteers.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;In the phantom, it was demonstrated that proton and quantitative sodium MR images share the same la","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144369045","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":"Detection of transient tissue displacement using wavelet MR elastography: Phantom validation and in vivo human brain repeatability study.","authors":"Yuan Le, Xiang Shan, Kevin J Glaser, Jun Chen, Phillip J Rossman, Yi Sui, Armando Manduca, John Huston, Richard L Ehman, Ziying Yin","doi":"10.1002/mrm.30612","DOIUrl":"https://doi.org/10.1002/mrm.30612","url":null,"abstract":"<p><strong>Purpose: </strong>While standard MR elastography (MRE) uses harmonic mechanical waves, there are some applications in which imaging and analysis of transient mechanical motion are of interest. Wavelet MRE has been developed for detecting broadband motion from transient excitation. The goal of this study was to evaluate the accuracy and efficiency of wavelet MRE for transient displacement detection in brain MRE applications.</p><p><strong>Methods: </strong>Transient motion was induced in a gel phantom, while MRE images were acquired using bipolar motion-encoding gradient (MEG) at multiple frequencies (20-200 Hz). Displacements were estimated using (1) combinations of multiple MEGs forming the wavelet MRE and (2) deconvolution from a single MEG. These estimated displacements were used to calculate the MRE phase for each MEG. Correlation (r²) between the calculated and acquired phases was evaluated. Three healthy volunteers were scanned twice in a clinical scanner using wavelet MRE with an occipital impact. Time-resolved brain translation, rotation, and maximal principal strain were calculated. Repeatability was assessed both qualitatively and through Pearson correlation.</p><p><strong>Results: </strong>Wavelet MRE outperformed standard MRE in displacement estimation, showing higher correlations between calculated and acquired phase, even with fewer phase offsets. In the volunteer study, consistent temporal motion dynamics and spatial maximal principal strain distributions across repeated scans demonstrated the repeatability of wavelet MRE.</p><p><strong>Conclusion: </strong>This study validated the accuracy and efficiency of wavelet MRE for broadband motion detection and demonstrated its feasibility and repeatability in vivo. This technique shows promise for advancing our understanding of the injury risks and mechanisms associated with sports-related head trauma.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144326189","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":"Dual-scan self-learning denoising for application in ultralow-field MRI.","authors":"Yuxiang Zhang, Wei He, Jiamin Wu, Zheng Xu","doi":"10.1002/mrm.30600","DOIUrl":"https://doi.org/10.1002/mrm.30600","url":null,"abstract":"<p><strong>Purpose: </strong>This study develops a self-learning method to denoise MR images for use in ultralow field (ULF) applications.</p><p><strong>Methods: </strong>We propose use of a self-learning neural network for denoising 3D MRI obtained from two acquisitions (dual scan), which are utilized as training pairs. Based on the self-learning method Noise2Noise, an effective data augmentation method and integrated learning strategy for enhancing model performance are proposed.</p><p><strong>Results: </strong>Experimental results demonstrate that (1) the proposed model can produce exceptional denoising results and outperform the traditional Noise2Noise method subjectively and objectively; (2) magnitude images can be effectively denoised comparing with several state-of-the-art methods on synthetic and real ULF data; and (3) the proposed method can yield better results on phase images and quantitative imaging applications than other denoisers due to the self-learning framework.</p><p><strong>Conclusions: </strong>Theoretical and experimental implementations show that the proposed self-learning model achieves improved performance on magnitude image denoising with synthetic and real-world data at ULF. Additionally, we test our method on calculated phase and quantification images, demonstrating its superior performance over several contrastive methods.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144317342","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":"The dynamic course of spontaneous muscular contractions assessed using multiple-point acquisition in diffusion-weighted stimulated echo imaging.","authors":"Martin Schwartz, Petros Martirosian, Victor Fritz, Günter Steidle, Bin Yang, Fritz Schick","doi":"10.1002/mrm.30576","DOIUrl":"https://doi.org/10.1002/mrm.30576","url":null,"abstract":"<p><strong>Purpose: </strong>The temporal course of spontaneous mechanical activities of musculature (SMAMs) is investigated using a novel multiple-point diffusion-weighted stimulated echo imaging sequence (MP-DW-STE) with adapted spatial and temporal resolution. For this purpose, different sequence settings and measurement parameters are applied.</p><p><strong>Methods: </strong>A single-shot MP-DW-STE imaging sequence with multiple signal rephasing by small flip angle RF pulses was developed to acquire image series during spontaneous muscle contractions with duration of several hundred milliseconds. Measurements were conducted on an incoherent motion phantom and in the calf muscles of eight healthy volunteers. The number and cross-sectional area of SMAM visualizations as well as the contractile behavior in terms of onset and duration of visible SMAMs was analyzed.</p><p><strong>Results: </strong>Measurements on the incoherent motion phantom confirmed the ability of the proposed technique to characterize dynamic incoherent motion as signal voids in series of images with a high temporal resolution of approximately 40 ms. All human subjects showed SMAMs with a median duration of 120 ms, therefore, visible in several diffusion-weighted images in a row. Contraction time of SMAMs was in the range of 80 to 120 ms for the soleus muscle. The MP-DW-STE sequence settings have shown to significantly influence the mean frequency and cross-sectional area of SMAMs.</p><p><strong>Conclusion: </strong>MP-DW-STE imaging allows for time-resolved recording of spontaneous muscular contractions and provides new insights into their dynamic course. This new feature can be used for better characterization of physiological SMAMs in healthy subjects and pathological SMAMs in patients suffering from neuromuscular diseases.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144317343","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":"High-density MRI coil arrays with integrated field monitoring systems for human connectome mapping.","authors":"Mirsad Mahmutovic, Manisha Shrestha, Gabriel Ramos-Llordén, Dongsuk Sung, Luke J Edwards, Ying Chu, Paul I Dubovan, Alina Müller, Sam-Luca J D Hansen, Anpreet Ghotra, Kerrin J Pine, Roland Müller, Nikolaus Weiskopf, Lawrence L Wald, Choukri Mekkaoui, Harald E Möller, Susie Y Huang, Boris Keil","doi":"10.1002/mrm.30606","DOIUrl":"https://doi.org/10.1002/mrm.30606","url":null,"abstract":"<p><strong>Purpose: </strong>To develop and test two high-density MRI coil arrays with integrated field monitoring systems for enhanced diffusion imaging with strong diffusion-sensitizing gradients.</p><p><strong>Methods: </strong>Two multichannel head coils were constructed for first- and second-generation 3T Connectome MRI scanners, incorporating 64 and 72 receive channels, respectively. The array coils were evaluated using RF bench-level metrics, including quality factor, tuning, matching, and coupling measurements. Imaging performance was comprehensively assessed through metrics such as SNR, <math> <semantics> <mrow> <msubsup><mrow><mi>B</mi></mrow> <mrow><mn>1</mn></mrow> <mrow><mo>+</mo></mrow> </msubsup> </mrow> <annotation>$$ {B}_1^{+} $$</annotation></semantics> </math> efficiency, and inter-channel noise correlations, and compared with and without field camera integration. Parallel imaging capability was evaluated using geometry (g)-factors. The field camera performance was characterized by quantifying phase errors and field probe FID lifetimes. In vivo DWI acquisitions with high <math> <semantics><mrow><mi>b</mi></mrow> <annotation>$$ b $$</annotation></semantics> </math> -values were performed to evaluate the system's ability to correct higher-order field perturbations.</p><p><strong>Results: </strong>The developed arrays demonstrated up to 1.4-fold higher SNR and superior g-factor performance when compared to a commercially available 32-channel head coil. Integration of the field camera was achieved without compromising the performance of either system. In vivo imaging with concurrent field monitoring enabled accurate spatiotemporal field corrections, significantly reducing geometric distortions, blurring, and ghosting in high <math> <semantics><mrow><mi>b</mi></mrow> <annotation>$$ b $$</annotation></semantics> </math> -value DWI.</p><p><strong>Conclusion: </strong>The integration of high-density MRI arrays with field monitoring systems facilitated the capture and correction of spatiotemporal field perturbations during strong gradient activity, substantially enhancing image quality and diffusion parameter mapping quality. These advancements provide a robust platform for exploring the structural intricacies of the human connectome.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144326190","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":"<ArticleTitle xmlns:ns0=\"http://www.w3.org/1998/Math/MathML\">Rapid, high-resolution and distortion-free <ns0:math> <ns0:mrow> <ns0:msubsup><ns0:mrow><ns0:mi>R</ns0:mi></ns0:mrow> <ns0:mrow><ns0:mn>2</ns0:mn></ns0:mrow> <ns0:mrow><ns0:mo>∗</ns0:mo></ns0:mrow> </ns0:msubsup> </ns0:mrow> </ns0:math> mapping of fetal brain using multi-echo radial FLASH and model-based reconstruction.","authors":"Xiaoqing Wang, Hongli Fan, Zhengguo Tan, Serge Vasylechko, Edward Yang, Ryne Didier, Onur Afacan, Martin Uecker, Simon K Warfield, Ali Gholipour","doi":"10.1002/mrm.30604","DOIUrl":"10.1002/mrm.30604","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;To develop a rapid, high-resolution, and distortion-free technique for simultaneous water-fat separation, &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {R}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {B}_0 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; mapping of the fetal brain at 3 T.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;A 2D multi-echo radial FLASH sequence with blip gradients is adapted for data acquisition during maternal free breathing. A calibrationless model-based reconstruction with sparsity constraints is developed to jointly estimate water, fat, &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {R}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {B}_0 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; field maps directly from k-space. This approach was validated and compared to reference methods using numerical and NIST phantoms and data from nine fetuses between 26 and 36 weeks of gestation age.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Both numerical and experimental phantom studies confirm good accuracy and precision. In fetal studies, model-based reconstruction yields quantitative &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {R}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; values in close agreement with those from a parallel imaging compressed sensing (PICS) technique using Graph Cut (intra-class correlation coefficient [ICC] = 0.9601), while providing enhanced image detail. Repeated scans confirm good reproducibility (ICC = 0.9213). Compared to multi-echo EPI, the proposed radial technique produces higher-resolution (1.1 &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ times $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; 1.1 &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ times $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; 3 mm &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {}^3 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; vs. 2-3 &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ times $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; 2-3 &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/mrow&gt; &lt;annotation&gt;$$ times $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; 3 mm &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt; &lt;/mo&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt; &lt;/msup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {}^3 $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt; &lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt; &lt;/msubsup&gt; &lt;/mrow&gt; &lt;annotation&gt;$$ {R}_2^{ast } $$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; maps with reduced dis","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144326188","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":"Diffusion probabilistic generative models for accelerated, in-NICU permanent magnet neonatal MRI.","authors":"Yamin Arefeen, Brett Levac, Bhairav Patel, Chang Ho, Jonathan I Tamir","doi":"10.1002/mrm.30585","DOIUrl":"https://doi.org/10.1002/mrm.30585","url":null,"abstract":"<p><strong>Purpose: </strong>Magnetic Resonance Imaging (MRI) enables non-invasive assessment of brain abnormalities during early life development. Permanent magnet scanners operating in the neonatal intensive care unit (NICU) facilitate MRI of sick infants, but have long scan times due to lower signal-to-noise ratios (SNR) and limited receive coils. This work accelerates in-NICU MRI with diffusion probabilistic generative models by developing a training pipeline accounting for these challenges.</p><p><strong>Methods: </strong>We establish a novel training dataset of clinical, 1 Tesla neonatal MR images in collaboration with Aspect Imaging and Sha'are Zedek Medical Center. We propose a pipeline to handle the low quantity and SNR of our real-world dataset (1) modifying existing network architectures to support varying resolutions; (2) training a single model on all data with learned class embedding vectors; (3) applying self-supervised denoising before training; and (4) reconstructing by averaging posterior samples. Retrospective under-sampling experiments, accounting for signal decay, evaluated each item of our proposed methodology. A clinical reader study with practicing pediatric neuroradiologists evaluated our proposed images reconstructed from <math> <semantics><mrow><mn>1</mn> <mo>.</mo> <mn>5</mn> <mo>×</mo></mrow> <annotation>$$ 1.5times $$</annotation></semantics> </math> under-sampled data.</p><p><strong>Results: </strong>Combining all data, denoising pre-training, and averaging posterior samples yields quantitative improvements in reconstruction. The generative model decouples the learned prior from the measurement model and functions at two acceleration rates without re-training. The reader study suggests that proposed images reconstructed from <math> <semantics><mrow><mi>R</mi> <mo>≈</mo> <mn>1</mn> <mo>.</mo> <mn>5</mn></mrow> <annotation>$$ Rapprox 1.5 $$</annotation></semantics> </math> under-sampled data are adequate for clinical use.</p><p><strong>Conclusion: </strong>Diffusion probabilistic generative models applied with the proposed pipeline to handle challenging real-world datasets could reduce the scan time of in-NICU neonatal MRI.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144317341","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":"Consensus recommendations for hyperpolarized [1-¹³C]pyruvate MRI multi-center human studies.","authors":"Shonit Punwani, Peder E Z Larson, Christoffer Laustsen, Jan VanderMeulen, Jan Henrik Ardenkjær-Larsen, Adam W Autry, James A Bankson, Jenna Bernard, Robert Bok, Lotte Bonde Bertelsen, Jenny Che, Albert P Chen, Rafat Chowdhury, Arnaud Comment, Charles H Cunningham, Duy Dang, Ferdia A Gallagher, Adam Gaunt, Yangcan Gong, Jeremy W Gordon, Ashley Grimmer, James Grist, Esben Søvsø Szocska Hansen, Mathilde Hauge Lerche, Richard L Hesketh, Jan-Bernd Hoevener, Ching-Yi Hsieh, Kayvan R Keshari, Sebastian Kozerke, Titus Lanz, Dirk Mayer, Mary McLean, Jae Mo Park, Jim Slater, Damian Tyler, Jean-Luc Vanderheyden, Cornelius von Morze, Fulvio Zaccagna, Vlad Zaha, Duan Xu, Daniel Vigneron","doi":"10.1002/mrm.30570","DOIUrl":"10.1002/mrm.30570","url":null,"abstract":"<p><p>MRI of hyperpolarized (HP) [1-¹³C]pyruvate allows in vivo assessment of metabolism and has translated into human studies across diseases at 15 centers worldwide. To determine consensus on best practice for multi-center studies for development of clinical applications. This paper presents the results of a two-round formal consensus building exercise carried out by experts with HP [1-¹³C]pyruvate human study experience. Twenty-nine participants from 13 sites brought together expertise in pharmacy methods, MR physics, translational imaging, and data analysis with the goal of providing recommendations and best practice statements on conduct of multi-center human studies of HP [1-¹³C]pyruvate MRI. Overall, the group reached consensus on approximately two-thirds of 246 statements in the questionnaire, covering HP ¹³C-pyruvate preparation; MRI system setup, calibration, and phantoms; acquisition and reconstruction; and data analysis and quantification. Consensus was present across categories. Examples include: (i) Different HP pyruvate preparation methods could be used in human studies, but the same release criteria have to be followed; (ii) site qualification and quality assurance must be performed with phantoms and the same field strength must be used, but the rest of the system setup and calibration methods could be determined by individual sites; (iii) the same pulse sequence and reconstruction methods were preferable, but the exact choice should be governed by the anatomical target; (iv) normalized metabolite area-under-curve values and metabolite area under curve were the preferred metabolism metrics. The consensus proces revealed that HP[1-¹³C] pyruvate MRI as a technology has progressed sufficiently to plan multi-center studies. The work confirmed areas of consensus for multi-center study conduct and identified where further research is required to ascertain best practice.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144310133","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":"Exact analytical solutions of the Bloch equation for the hyperbolic-secant and chirp pulses.","authors":"Ryan H B Smith, Donald Garwood, Michael Garwood","doi":"10.1002/mrm.30603","DOIUrl":"https://doi.org/10.1002/mrm.30603","url":null,"abstract":"<p><strong>Purpose: </strong>To improve the accuracy and generality of analytical solutions of the Bloch equation for the hyperbolic-secant (HS1) and chirp pulses in order to facilitate application to truncated and composite pulses and use in quantitative methods.</p><p><strong>Theory and methods: </strong>Previous analytical solutions of the Bloch equation during an HS1 pulse driving function are refined and extended in this exact solution for arbitrary initial magnetization and pulse parameters including asymmetrical truncation. An unapproximated general solution during the chirp pulse is derived in a non-spinor formulation for the first time. The solution on the extended complex plane for the square pulse is included for completeness.</p><p><strong>Results: </strong>The exact solutions for the HS1, chirp, and square pulses demonstrate high consistency with Runge-Kutta simulations for all included pulse and isochromat parameters. The HS1 solution is strictly more accurate than the most complete prior general solution. The analytical solution of the BIR-4 composite pulse constructed using asymmetrically truncated HS1 component pulses likewise agrees with simulation results.</p><p><strong>Conclusion: </strong>The derived analytical solutions for the Bloch equation during an HS1 or chirp pulse are exact regardless of pulse parameters and initial magnetization and precisely conform with simulations enabling their use in quantitative MRI applications and setting a foundation for the analytical consideration of relaxation and pulses in multiply rotating frames.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144310134","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}