检索结果-内蒙古大学图书馆

作者： Shin, Peter J. Larson, Peder E.Z. Uecker, Martin Reed, Galen D. Kerr, Adam B. Tropp, James Ohliger, Michael A. Nelson, Sarah J. Pauly, John M. Lustig, Michael Vigneron, Daniel B. Department of Radiology and Biomedical Imaging University of California at San Francisco 1700 4th Street San FranciscoCA94158 United States UC Berkeley - UCSF Graduate Program in Bioengineering CA United States Department of Electrical Engineering and Computer Sciences University of California at Berkeley BerkeleyCA United States Magnetic Resonance Systems Research Laboratory Department of Electrical Engineering Stanford University StanfordCA United States General Electric Healthcare FremontCA United States

Purpose A chemical shift separation technique for hyperpolarized 13C metabolic imaging with high spatial and temporal resolution was developed. Specifically, a fast three-dimensional pulse sequence and a reconstruction method were implemented to acquire signals from multiple 13C species simultaneously with subsequent separation into individual images. Theory and Methods A stack of flyback echo-planar imaging readouts and a set of multiband excitation radiofrequency pulses were designed to spatially modulate aliasing patterns of the acquired metabolite images, which translated the chemical shift separation problem into parallel imaging reconstruction problem. An eight-channel coil array was used for data acquisition and a parallel imaging method based on nonlinear inversion was developed to separate the aliased images. Results Simultaneous acquisitions of pyruvate and lactate in a phantom study and in vivo rat experiments were performed. The results demonstrated successful separation of the metabolite distributions into individual images having high spatial resolution. Conclusion This method demonstrated the ability to provide accelerated metabolite imaging in hyperpolarized 13C MR using multichannel coils, tailored readout, and specialized RF pulses. © 2014 Wiley Periodicals, Inc.

关键词： Separation

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Data Format Standardization and DICOM Integration for Hyperpolarized 13C MRI

arXiv

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arXiv 2024年

作者： Diaz, Ernesto Sriram, Renuka Gordon, Jeremy W. Sinha, Avantika Liu, Xiaoxi Sahin, Sule Crane, Jason Olson, Marram P. Chen, Hsin-Yu Bernard, Jenna Vigneron, Daniel B. Wang, Zhen Jane Xu, Duan Larson, Peder E.Z. Department of Radiology and Biomedical Imaging University of California - San Francisco San FranciscoCA United States UC Berkeley-UCSF Graduate Program in Bioengineering University of California Berkeley United States University of California San FranciscoCA United States

Hyperpolarized (HP) 13C MRI has shown promise as a valuable modality for in vivo measurements of metabolism and is currently in human trials at 15 research sites worldwide. With this growth it is important to adopt standardized data storage practices as it will allow sites to meaningfully compare data. In this paper we (1) describe data that we believe should be stored and (2) demonstrate pipelines and methods that utilize the Digital Imaging and Communications in Medicine (DICOM) standard. This includes proposing a set of minimum set of information that is specific to HP 13C MRI studies. We then show where the majority of these can be fit into existing DICOM Attributes, primarily via the "Contrast/Bolus" module. We also demonstrate pipelines for utilizing DICOM for HP 13C MRI. DICOM is the most common standard for clinical medical image storage and provides the flexibility to accommodate the unique aspects of HP 13C MRI, including the HP agent information but also spectroscopic and metabolite dimensions. The pipelines shown include creating DICOM objects for studies on human and animal imaging systems with various pulse sequences. We also show a python-based method to efficiently modify DICOM objects to incorporate the unique HP 13C MRI information that is not captured by existing pipelines. Moreover, we propose best practices for HP 13C MRI data storage that will support future multi-site trials, research studies and technical developments of this imaging technique. © 2024, CC BY.

关键词： Magnetic resonance imaging

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QSMGAN: Improved quantitative susceptibility mapping using 3d generative adversarial networks with increased receptive field

arXiv

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arXiv 2019年

作者： Chen, Yicheng Jakary, Angela Hess, Christopher P. Lupo, Janine UC Berkeley-UCSF Graduate Program in Bioengineering University of California Berkeley University of California San Francisco California San FranciscoCA94158 Department of Radiology and Biomedical Imaging University of California San Francisco San FranciscoCA94158 United States

Quantitative susceptibility mapping (QSM) is a powerful MRI technique that has shown great potential in quantifying tissue susceptibility in numerous neurological disorders. However, the intrinsic ill-posed dipole inversion problem greatly affects the accuracy of the susceptibility map. We proposed QSMGAN: A 3D deep convolutional neural network approach based on improved U-Net with increased phase receptive field and further refined the network using the WGAN-GP training strategy. Our method could generate accurate and realistic QSM from single orientation phase maps efficiently and performed significantly better than traditional non-learning-based dipole inversion algorithms. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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Association of body shape and fracture risk

Association of body shape and fracture risk

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第六届国际骨质疏松及骨矿盐疾病学术会议

作者： Bo Fan Joseph P Wilson John A Shepherd Department of Radiology & Biomedical Imaging University of California San FranciscoUSA Department of Radiology & Biomedical Imaging University of California San FranciscoUSA UC Berkeley-UCSF Graduate Program in BioengineeringSan FranciscoCA US

＜正＞Objective:To examine theindependent association ofbody shape（total volume,trunk volume,and trunk to leg volume ratio）tofracture risk. Methods:We performed a cross-sectional study of the NHANES 1999-2004 survey data downloaded from the study *** individualshad both a valid dual-energy Xray absorptiometry（DXA） scan and known fracture status. The body shape measureswere derived using DXA whole

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Clinical anthropometrics and body composition from 3D whole-body surface scans (vol 70, pg 1265, 2016)

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EUROPEAN JOURNAL OF CLINICAL NUTRITION 2021年第3期75卷 574-574页

作者： Ng, B. K. Hinton, B. J. Fan, B. Kanaya, A. M. Shepherd, J. A. Department of Radiology and Biomedical Imaging University of California San Francisco San Francisco USA The UC Berkeley—UCSF Graduate Program in Bioengineering San Francisco USA Department of Medicine University of California San Francisco San Francisco USA

A Correction to this paper has been published: https://***/10.1038/s41430-020-00808-y

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Extreme MRI: Large-scale volumetric dynamic imaging from continuous non-gated acquisitions

arXiv

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arXiv 2019年

作者： Ong, Frank Zhu, Xucheng Cheng, Joseph Y. Johnson, Kevin M. Larson, Peder E.Z. Vasanawala, Shreyas S. Lustig, Michael Stanford University CA United States UC Berkeley-UCSF Graduate Program in Bioengineering University of California San Francisco University of California BerkeleyCA United States University of Wisconsin MadisonWI United States University of California San FranciscoCA United States

Purpose: To develop a framework to reconstruct large-scale volumetric dynamic MRI from rapid continuous and non-gated acquisitions, with applications to pulmonary and dynamic contrast enhanced (DCE) imaging. Theory and Methods: The problem considered here is a reconstruction of hundred-gigabytes of dynamic volumetric image data from a few gigabytes of k-space data, acquired continuously over several minutes. This is a vastly under-determined optimization, with problem sizes heavily stressing compute resources as well as memory management and storage. To overcome these challenges, we leverage intrinsic three dimensional (3D) trajectories, such as 3D radial and 3D cones, with ordering that incoherently cover time and k-space over the entire acquisition. We then propose two innovations: (1) A compressed representation using multi-scale low rank matrix factorization that both constrains the reconstruction problem and reduces its memory footprint. (2) Stochastic optimization to reduce computation, improve memory locality and minimize communications between threads and processors. We demonstrate the feasibility of the proposed method on DCE imaging acquired with a golden-angle ordered 3D cones trajectory and pulmonary imaging acquired with a bit-reversed ordered 3D radial trajectory. We compare it with "soft-gated" dynamic reconstruction for DCE and respiratory resolved reconstruction for pulmonary imaging. Results: The proposed technique shows transient dynamics that are not seen in gating based methods. When applied to datasets with irregular, or non-repetitive motions, the proposed method also displays sharper image features. Conclusion: We demonstrated a method that can reconstruct massive 3D dynamic image series in the extreme undersampling and extreme computation setting. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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A metabolite specific 3D stack-of-spiral bSSFP sequence for improved lactate imaging in hyperpolarized [1-13C]pyruvate studies on a 3T clinical scanner

arXiv

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arXiv 2020年

作者： Tang, Shuyu Bok, Robert Qin, Hecong Reed, Galen VanCriekinge, Mark Santos, Romelyn Delos Overall, William Santos, Juan Gordon, Jeremy Wang, Zhen Jane Vigneron, Daniel B. Larson, Peder E.Z. UC Berkeley-UCSF Graduate Program in Bioengineering University of California San Francisco University of California Berkeley United States Department of Radiology and Biomedical Imaging University of California - San Francisco San FranciscoCA United States HeartVista Los AltosCA United States

Purpose: The balanced steady-state free precession sequence has been previously explored to improve the efficient use of non-recoverable hyperpolarized 13C magnetization, but suffers from poor spectral selectivity and long acquisition time. The purpose of this study was to develop a novel metabolite-specific 3D bSSFP ("MS-3DSSFP") sequence with stack-of-spiral readouts for improved lactate imaging in hyperpolarized [1-13C]pyruvate studies on a clinical 3T scanner. Methods: Simulations were performed to evaluate the spectral response of the MS-3DSSFP sequence. Thermal 13C phantom experiments were performed to validate the MS-3DSSFP sequence. In vivo hyperpolarized [1-13C]pyruvate studies were performed to compare the MS-3DSSFP sequence with metabolite specific gradient echo ("MS-GRE") sequences for lactate imaging. Results: Simulations, phantom and in vivo studies demonstrate that the MS-3DSSFP sequence achieved spectrally selective excitation on lactate while minimally perturbing other metabolites. Compared with MS-GRE sequences, the MS-3DSSFP sequence showed approximately a 2.5-fold SNR improvement for lactate imaging in rat kidneys, prostate tumors in a mouse model and human kidneys. Conclusions: Improved lactate imaging using the MS-3DSSFP sequence in hyperpolarized [1-13C]pyruvate studies was demonstrated in animals and humans. The MS-3DSSFP sequence could be applied for other clinical applications such as in the brain or adapted for imaging other metabolites such as pyruvate and bicarbonate. Copyright © 2020, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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A compact planar triple-nuclear coil for small animal 1H, 13C, and 31P Metabolic MR Imaging at 14.1 T

arXiv

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arXiv 2021年

作者： Leynes, A.P. Chen, Y. Sukumar, S. Xu, D. Zhang, X. Department of Radiology and Biomedical Imaging University of California San Francisco Byers Hall 102D 1700 4th Street San FranciscoCA94158 United States UC Berkeley and UCSF Joint Graduate Group in Bioengineering San Francisco BerkeleyCA United States

Multi-nuclear radio-frequency (RF) coils at ultrahigh field strengths are challenging to develop due to the high operating frequency, increased electromagnetic interaction among the coil elements, and increased electromagnetic interaction between the coils and the subject. In this work, a triple-nuclear surface coil for 1H, 13C, and 31P for small animal metabolic imaging at 14.1 T is built by nesting three surface coil geometries: a lumped-element L-C loop coil, a butterfly coil, and a microstrip transmission line (MTL) resonator. The loop coil, butterfly coil, and MTL are tuned to 31P, 13C, and 1H, respectively. The successful bench tests and phantom imaging with this novel triple-nuclear coil demonstrates the feasibility of the design for triple-nuclear MR imaging and spectroscopy studies at the ultrahigh field of 14.1 T. In particular, the microstrip transmission line resonator demonstrates excellent coil performance for proton imaging at 600 MHz, where conventional lumped-element design is limited. © 2021, CC BY.

关键词： Resonators

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A Regional bolus tracking and Real-time B1 Calibration method for Hyperpolarized 13C MRI

arXiv

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arXiv 2020年

作者： Tang, Shuyu Milshteyn, Eugene Reed, Galen Gordon, Jeremy Bok, Robert Zhu, Xucheng Zhu, Zihan Vigneron, Daniel B. Larson, Peder E.Z. UC Berkeley-UCSF Graduate Program in Bioengineering University of California San Francisco United States University of California Berkeley United States Department of Radiology and Biomedical Imaging University of California - San Francisco San FranciscoCA United States HeartVista Los AltosCA United States

Purpose: Acquisition timing and B1 calibration are two key factors that affect the quality and accuracy of hyperpolarized 13C MRI. The goal of this project was to develop a new approach using regional bolus tracking to trigger Bloch-Siegert B1 mapping and real-time B1 calibration based on regional B1 measurements, followed by dynamic imaging of hyperpolarized 13C metabolites in ***: The proposed approach was implemented on a system which allows real-time data processing and real-time control on the sequence. Real-time center frequency calibration upon the bolus arrival was also added. The feasibility of applying the proposed framework for in vivo hyperpolarized 13C imaging was tested on healthy rats, tumor-bearing mice and a healthy volunteer on a clinical 3T scanner following hyperpolarized [1-13C]pyruvate injection. Multichannel receive coils were used in the human ***: Automatic acquisition timing based on either regional bolus peak or bolus arrival was achieved with the proposed framework. Reduced blurring artifacts in real-time reconstructed images were observed with real-time center frequency calibration. Real-time computed B1 scaling factors agreed with real-time acquired B1 maps. Flip angle correction using B1 maps results in a more consistent quantification of metabolic activity (i.e, pyruvate-to-lactate conversion, kPL). Experiment recordings are provided to demonstrate the real-time actions during the ***: The proposed method was successfully demonstrated on animals and a human volunteer, and is anticipated to improve the efficient use of the hyperpolarized signal as well as the accuracy and robustness of hyperpolarized 13C imaging. Copyright © 2020, The Authors. All rights reserved.

关键词： Mapping

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Performance Evaluation and Comparison of two Triple-nuclear RF Resonators for 1H/19F/31P MR Imaging at 9.4T

Performance Evaluation and Comparison of two Triple-nuclear ...

引用

IEEE International Conference on Real-time Computing and Robotics (RCAR)

作者： Feng Du Shengping Liu Nan Li Congcong Liu Qiaoyan Chen Shuai Zhang Haifeng Wang Xiaoliang Zhang Ye Li Chongqing University of Technology Chongqing Chongqing China Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen Guang Dong China UCSF/UC Berkeley Joint Graduate Group in Bioengineering San Francisco CA USA

ISBN: (数字)9781728137261

ISBN: (纸本)9781728137278

Radio frequency (RF) coils are critical devices in magnetic resonance (MR) systems for transmitting and receiving magnetic resonance signals. However, the required high operating frequency at ultrahigh magnetic fields makes the design of highly efficient radio frequency (RF) transmit or receive coils technically challenging. This is particularly true in the double-tuned or triple-tuned RF coils usually required in heteronuclear MRI and MRS where multiple nuclei, such as 1 H, 19 F, and 31 P, are involved. The performance of RF coils is a critically important factor for realizing the high sensitivity provided by ultrahigh magnetic fields to contribute towards the advancement of a novel human in vivo application at 9.4T. In this work, two different configurations of novel triple-nuclear ( 1 H/ 19 F/ 31 P) RF resonators were proposed for the ultrahigh field 9.4T applications. We also reported on the design and construction, and a field-circuit co-simulation was used to obtain the S-parameters, B 1 + field and specific absorption rate (SAR) distributions to evaluate and compare their performance. And the characteristics and advantages of the proposed two different configurations of triple-nuclear RF resonators in the applications of 1 H/ 19 F/ 31 P at ultrahigh magnetic field were investigated.

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