高场磁共振下并行激发技术的相关研究
|
摘要
磁共振成像技术是一种非介入式探测技术,有着能够反映诸多结构功能等生理差异与变化的多重对比机制,在当今的临床诊断和医学研究中有着极其重要的意义。自磁共振成像技术应用以来,为满足人们对成像高分辨率、高信噪比的需求,扫描仪的主磁场场强不断提升,对应的射频脉冲载波频率也随之提高。其结果是短波长的射频场与负载的耦合效应增强,导致射频能量在空间上的不均匀传递、从而对空间内质子的不均匀激发。作为磁共振信号源的质子激发的不均匀性的直接后果是,成像结果不能准确反映其真实信息,从而无法提供用于临床诊断和研究的可靠参照。针对该问题,本文以实现高场下射频场的不均匀性补偿、从而快速高质量成像为目标,从激发脉冲序列设计、线圈阵列的结构设计和实际K空间轨迹测量这三个方面展开研究工作。
(1)关于激发脉冲序列设计
为实现高场下三维目标区域内质子的均匀快速激发,提出了一种基于并行激发技术的激发脉冲序列的优化设计方法。该方法通过优化K空间轨迹的设计来优化脉冲序列时长、激发效果以及临床安全性,并已经高场下的建模仿真验证了其有效性。
更具体的,该方法通过寻找优化的方式来限定K空间轨迹的分布范围、定义对K空间内的欠采样,来缩短脉冲序列时长；由于该方法所定义的K空间轨迹分布范围与激发目标特定相关,因此对于在该分布范围内采样的K空间轨迹、针对性的设计射频脉冲即能保证实现期望的激发效果；此外,该方法放开了对于三维K空间轨迹类型选择的限制,允许在设计中选择最优轨迹类型来减小激发所需射频脉冲的幅值与能量,从而提升了临床安全性。
(2)关于线圈阵列的结构设计
为在保证成像质量前提下充分发挥三维并行激发技术的加速作用,提出了一种用于并行激发技术第三维激发加速的线圈阵列的初步设计方法与评估方法。此前尚未有关于第三维扩展的线圈阵列的报道,是由本文首次提出的创新设计,因此在设计中借鉴了用于磁共振并行成像技术的线圈阵列的设计思路。经高场下的建模仿真验证了该设计方法与评估方法的有效性。启用此类线圈阵列作为发射线圈,结合以本文提出的用于三维空间选择性激励的序列设计方法,能够有效的缩短激发脉冲序列时长,从而提高成像时间分辨率
(3)关于实际K空间轨迹测量
为确保并行激发脉冲序列对目标区域质子的准确激发,研究了用于解决激发K空间轨迹形变问题的实际K空间轨迹测量方法。在永磁磁共振扫描仪上实验测试了经典的序列方式测量方法,结合理论与实验分析其优缺点,并通过将实际测得的K空间轨迹与理想轨迹进行成像重建的结果比较,验证了序列方式测量方法的有效性。
Magnetic resonance imaging (MRI), with its excellent soft tissue contrast, non-invasive character, is a promising medical imaging technique used in radiology to visualize internal structures and functions of the body in detail. However, the process of MRI formation introduces various artifacts that may corrupt a truly quantitative evaluation. One of major artifacts stems from the intra-slice intensity non-uniformity due to severe radio-frequency (RF) inhomogeneity in high field or ultra high field MRI, since the RF field propagating through the object has shorter wavelengths and greater attenuation, which induces unwanted intensity variations of the signal. This problem will be addressed throughout this thesis, by researching in transmit pulse sequence design, coil array design, and K-space trajectory measurement.
(1) Transmit pulse sequence design
Based on recently-developed parallel transmission techniques, an optimized3D tailored RF (TRF) pulse, designed with a novel3D adaptive trajectory, is proposed to improve and accelerate volume selective excitation. The feasibility of this method is confirmed by simulations of ultra-high field cases.
There are three key factors concerning a practical use of a transmit pulse sequence: excitation uniformity, pulse duration, and RF energy relating to clinical safety issues. The method optimally defines the k-space trajectory to improve all of the three key factors.
In detail, the method dedicatedly defines and limits the traversing area of the k-space trajectory, to find an appropriate way to subsample the k-space, so as to shorten the pulse duration. The dedicatedly defined traversing area is supposed to be mostly responsible for the excitation target, so that a promising uniform excitation can be achieved in the target region. Moreover, because the method allows designer to introduce various types of3D k-space trajectory, one can optimally choose one type to help reduce the peak RF pulse amplitude and the entire energy for the excitation, so as to improve RF safety margins in clinical applications.
(2) Coil array design
A brand new type of coil array geometry is proposed for3D parallel excitation. Such geometry is expected to be used to explore excitation acceleration in an extra dimension, compared to the conventional transmit coil array, so that to mitigate degradation in excitation accuracy at high acceleration factors. Similar type of coil array geometry specialized for parallel imaging is used as reference for those for parallel excitation. The performance of the proposed coil array geometry is demonstrated via simulation based comparison, showing its ability to adapt the3D parallel transmit pulse sequence, to further accelerate excitation pulse length, and to improve excitation accuracy. An evaluation method is also proposed to assess the parallel excitation performance of coil array geometries.
(3) K-space trajectory measurement
Actual K-space trajectory measurement techniques was studied and their performance are tested on a permanent magnet scanner, in accounting for the deviations from the theoretical k-space trajectory and achieving accurate excitation of target pattern. The feasibility of the techniques is confirmed by comparisons of image reconstruction results based on the expected and the measured trajectories.
(1)关于激发脉冲序列设计
为实现高场下三维目标区域内质子的均匀快速激发,提出了一种基于并行激发技术的激发脉冲序列的优化设计方法。该方法通过优化K空间轨迹的设计来优化脉冲序列时长、激发效果以及临床安全性,并已经高场下的建模仿真验证了其有效性。
更具体的,该方法通过寻找优化的方式来限定K空间轨迹的分布范围、定义对K空间内的欠采样,来缩短脉冲序列时长；由于该方法所定义的K空间轨迹分布范围与激发目标特定相关,因此对于在该分布范围内采样的K空间轨迹、针对性的设计射频脉冲即能保证实现期望的激发效果；此外,该方法放开了对于三维K空间轨迹类型选择的限制,允许在设计中选择最优轨迹类型来减小激发所需射频脉冲的幅值与能量,从而提升了临床安全性。
(2)关于线圈阵列的结构设计
为在保证成像质量前提下充分发挥三维并行激发技术的加速作用,提出了一种用于并行激发技术第三维激发加速的线圈阵列的初步设计方法与评估方法。此前尚未有关于第三维扩展的线圈阵列的报道,是由本文首次提出的创新设计,因此在设计中借鉴了用于磁共振并行成像技术的线圈阵列的设计思路。经高场下的建模仿真验证了该设计方法与评估方法的有效性。启用此类线圈阵列作为发射线圈,结合以本文提出的用于三维空间选择性激励的序列设计方法,能够有效的缩短激发脉冲序列时长,从而提高成像时间分辨率
(3)关于实际K空间轨迹测量
为确保并行激发脉冲序列对目标区域质子的准确激发,研究了用于解决激发K空间轨迹形变问题的实际K空间轨迹测量方法。在永磁磁共振扫描仪上实验测试了经典的序列方式测量方法,结合理论与实验分析其优缺点,并通过将实际测得的K空间轨迹与理想轨迹进行成像重建的结果比较,验证了序列方式测量方法的有效性。
Magnetic resonance imaging (MRI), with its excellent soft tissue contrast, non-invasive character, is a promising medical imaging technique used in radiology to visualize internal structures and functions of the body in detail. However, the process of MRI formation introduces various artifacts that may corrupt a truly quantitative evaluation. One of major artifacts stems from the intra-slice intensity non-uniformity due to severe radio-frequency (RF) inhomogeneity in high field or ultra high field MRI, since the RF field propagating through the object has shorter wavelengths and greater attenuation, which induces unwanted intensity variations of the signal. This problem will be addressed throughout this thesis, by researching in transmit pulse sequence design, coil array design, and K-space trajectory measurement.
(1) Transmit pulse sequence design
Based on recently-developed parallel transmission techniques, an optimized3D tailored RF (TRF) pulse, designed with a novel3D adaptive trajectory, is proposed to improve and accelerate volume selective excitation. The feasibility of this method is confirmed by simulations of ultra-high field cases.
There are three key factors concerning a practical use of a transmit pulse sequence: excitation uniformity, pulse duration, and RF energy relating to clinical safety issues. The method optimally defines the k-space trajectory to improve all of the three key factors.
In detail, the method dedicatedly defines and limits the traversing area of the k-space trajectory, to find an appropriate way to subsample the k-space, so as to shorten the pulse duration. The dedicatedly defined traversing area is supposed to be mostly responsible for the excitation target, so that a promising uniform excitation can be achieved in the target region. Moreover, because the method allows designer to introduce various types of3D k-space trajectory, one can optimally choose one type to help reduce the peak RF pulse amplitude and the entire energy for the excitation, so as to improve RF safety margins in clinical applications.
(2) Coil array design
A brand new type of coil array geometry is proposed for3D parallel excitation. Such geometry is expected to be used to explore excitation acceleration in an extra dimension, compared to the conventional transmit coil array, so that to mitigate degradation in excitation accuracy at high acceleration factors. Similar type of coil array geometry specialized for parallel imaging is used as reference for those for parallel excitation. The performance of the proposed coil array geometry is demonstrated via simulation based comparison, showing its ability to adapt the3D parallel transmit pulse sequence, to further accelerate excitation pulse length, and to improve excitation accuracy. An evaluation method is also proposed to assess the parallel excitation performance of coil array geometries.
(3) K-space trajectory measurement
Actual K-space trajectory measurement techniques was studied and their performance are tested on a permanent magnet scanner, in accounting for the deviations from the theoretical k-space trajectory and achieving accurate excitation of target pattern. The feasibility of the techniques is confirmed by comparisons of image reconstruction results based on the expected and the measured trajectories.
引文
[1]U. Katscher, et al., "Transmit SENSE," Magnetic Resonance in Medicine, vol.49, pp. 144-150,2003.
[2]Y. Zhu, "Parallel excitation with an array of transmit coils," Magnetic Resonance in Medicine, vol.51, pp.775-784,2004.
[3]W. Grissom, et al., "Spatial domain method for the design of RF pulses in multicoil parallel excitation," Magnetic Resonance in Medicine, vol.56, pp.620-629,2006.
[4]K. Setsompop, et al., "Parallel RF transmission with eight channels at 3 Tesla," Magnetic Resonance in Medicine, vol.56, pp.1163-1171,2006.
[5]D. Xu, et al., "A noniterative method to design large-tip-angle multidimensional spatially-selective radio frequency pulses for parallel transmission," Magnetic Resonance in Medicine, vol.58, pp.326-334,2007.
[6]W. A. Grissom, et al., "Additive angle method for fast large-tip-angle RF pulse design in parallel excitation," Magnetic Resonance in Medicine, vol.59, pp.779-787,2008.
[7]D. Xu, et al., "Designing multichannel, multidimensional, arbitrary flip angle RF pulses using an optimal control approach," Magnetic Resonance in Medicine, vol.59, pp.547-560,2008.
[8]W. A. Grissom, et al., "Fast Large-Tip-Angle Multidimensional and Parallel RF Pulse Design in MRI," Medical Imaging, IEEE Transactions on, vol.28, pp.1548-1559, 2009.
[9]J. L. Ulloa, et al., "Exploring 3D RF shimming for slice selective imaging," in Proceedings of the 13th Annual Meeting of ISMRM, Miami Beach, FL, USA,2005, p. 21.
[10]Z. Zhang, et al., "Reduction of transmitter B1 inhomogeneity with transmit SENSE slice-select pulses," Magnetic Resonance in Medicine, vol.57, pp.842-847,2007.
[11]K. Setsompop, et al., "Slice-selective RF pulses for in vivo B1+ inhomogeneity mitigation at 7 tesla using parallel RF excitation with a 16-element coil," Magnetic Resonance in Medicine, vol.60, pp.1422-1432,2008.
[12]A. C. Zelinski, et al., "Sparsity-Enforced Slice-Selective MRI RF Excitation Pulse Design," Medical Imaging, IEEE Transactions on, vol.27, pp.1213-1229,2008.
[13]C.-Y. Yip, et al., "Joint design of trajectory and RF pulses for parallel excitation," Magnetic Resonance in Medicine, vol.58, pp.598-604,2007.
[14]C. Ma, et al., "Joint design of spoke trajectories and RF pulses for parallel excitation," Magnetic Resonance in Medicine, pp. n/a-n/a,2010.
[15]C. y. Yip, et al., "Advanced three-dimensional tailored RF pulse for signal recovery in T2*-weighted functional magnetic resonance imaging," Magnetic Resonance in Medicine, vol.56, pp.1050-1059,2006.
[16]G. T. Luk-Pat, et al., "High-resolution three-dimensional in vivo imaging of atherosclerotic plaque," Magnetic Resonance in Medicine, vol.42, pp.762-771,1999.
[17]G. Yang, et al., "Locally focused 3D coronary imaging using volume-selective RF excitation," Magnetic Resonance in Medicine, vol.41, pp.171-178,1999.
[18]L. A. Crowe, et al., "Volume-selective 3D turbo spin echo imaging for vascular wall imaging and distensibility measurement," Journal of Magnetic Resonance Imaging, vol.17, pp.572-580,2003.
[19]M. Stuber, et al., "Selective three-dimensional visualization of the coronary arterial lumen using arterial spin tagging," Magnetic Resonance in Medicine, vol.47, pp. 322-329,2002.
[20]D. C. Alsop and J. A. Detre, "Multisection cerebral blood flow MR imaging with continuous arterial spin labeling," Radiology, vol.208, pp.410-416, August 1,1998 1998.
[21]J. P. Mugler, et al., "Optimized Single-Slab Three-dimensional Spin-Echo MR Imaging of the Brain," Radiology, vol.216, pp.891-899,2000.
[22]P. J. W. Pouwels, et al., "Human Gray Matter:Feasibility of Single-Slab 3D Double Inversion-Recovery High-Spatial-Resolution MR Imaging," Radiology, vol.241, pp. 873-879,2006.
[23]B. Moraal, et al., "Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis," European Radiology, vol.18, pp.2311-2320,2008.
[24]K.-N. K. N. Darji, G. Patel, H-P. Fautz, J. Bernarding, O. Speck, "Evaluating further benefits of B1+ homogenity when more transmit chnnels are used," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p.324.
[25]J. W. P. N. I. Avdievich, H. P. Hetherington, "Improved longitudinal coverage for human brain at 7T:A 16 Element Transceiver Array," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p.328.
[26]N. I. A. H. P. Hetherington, and J. W. Pan, "Multiplexed RF Transmission for Transceiver Arrays at 7T," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p. 163.
[27]P. Mansfield and B. Chapman, "Active magnetic screening of coils for static and time-dependent magnetic field generation in NMR imaging," Journal of Physics E: Scientific Instruments, vol.19, p.540,1986.
[28]H. M. Gach, et al., "A programmable pre-emphasis system," Magnetic Resonance in Medicine, vol.40, pp.427-431,1998.
[29]R. E. Wysong, et al., "A novel eddy current compensation scheme for pulsed gradient systems," Magnetic Resonance in Medicine, vol.31, pp.572-575,1994.
[30]F. Calamante, et al., "Correction for eddy current induced Bo shifts in diffusion-weighted echo-planar imaging," Magnetic Resonance in Medicine, vol.41, pp.95-102,1999.
[31]N. G. Papadakis, et al., "Gradient preemphasis calibration in diffusion-weighted echo-planar imaging," Magnetic Resonance in Medicine, vol.44, pp.616-624,2000.
[32]A. L. Alexander, et al., "Elimination of eddy current artifacts in diffusion-weighted echo-planar images:The use of bipolar gradients," Magnetic Resonance in Medicine, vol.38, pp.1016-1021,1997.
[33]X. J. Zhou, et al., "Artifacts induced by concomitant magnetic field in fast spin-echo imaging," Magnetic Resonance in Medicine, vol.40, pp.582-591,1998.
[34]C. B. Ahn and Z. H. Cho, "Analysis of eddy currents in nuclear magnetic resonance imaging," Magnetic Resonance in Medicine, vol.17, pp.149-163,1991.
[35]T. G. Reese, et al., "Reduction of eddy-current-induced distortion in diffusion MRI using a twice-refocused spin echo," Magnetic Resonance in Medicine, vol.49, pp. 177-182,2003.
[36]D. M. Spielman and J. M. Pauly, "Spiral imaging on a small-bore system at 4.7t," Magnetic Resonance in Medicine, vol.34, pp.580-585,1995.
[37]T. Onodera, et al., "A method of measuring field-gradient modulation shapes. Application to high-speed NMR spectroscopic imaging," Journal of Physics E: Scientific Instruments, vol.20, p.416,1987.
[38]G. F. Mason, et al., "A Method to measure arbitrary k-space trajectories for rapid MR imaging," Magnetic Resonance in Medicine, vol.38, pp.492-496,1997.
[39]Y. Zhang, et al., "A novel k-space trajectory measurement technique," Magnetic Resonance in Medicine, vol.39, pp.999-1004,1998.
[40]J. H. Duyn, et al., "Simple Correction Method fork-Space Trajectory Deviations in MRI," Journal of Magnetic Resonance, vol.132, pp.150-153,1998.
[41]B. C. Pruessmann KP, De Zanche N, "Magnetic field monitoring during MRI acquisition improves image reconstruction," presented at the Proc 13th Annual Meeting ISMRM, Miami Beach,2005.
[42]B. C. De Zanche N, Massner JA, Pruessmann KP, "Advances in NMR probe technology for magnetic field monitoring," presented at the Proc 14th Annual Meeting ISMRM, Seattle,2006.
[43]C. Barmet, et al., "Spatiotemporal magnetic field monitoring for MR," Magnetic-Resonance in Medicine, vol.60, pp.187-197,2008.
[44]P. Sipila, et al., "Robust, susceptibility-matched NMR probes for compensation of magnetic field imperfections in magnetic resonance imaging (MRI)," Sensors and Actuators A:Physical, vol.145-146, pp.139-146,2008.
[45]K. K. Bernstein MA, Zhou ZJ, Handbook of MRI pulse sequences. Boston:Academic Press,2004.
[46]J. Pauly, et al., "A k-space analysis of small-tip-angle excitation," Journal of Magnetic Resonance (1969), vol.81, pp.43-56,1989.
[47]S. Saekho, et al., "Fast-kz three-dimensional tailored radiofrequency pulse for reduced B1 inhomogeneity," Magnetic Resonance in Medicine, vol.55, pp.719-724, 2006.
[48]J. M. Pauly, et al., "A three-dimensional spin-echo or inversion pulse," Magnetic Resonance in Medicine, vol.29, pp.2-6,1993.
[49]J. Pauly, et al., "Parameter relations for the Shinnar-Le Roux selective excitation pulse design algorithm [NMR imaging]," Medical Imaging, IEEE Transactions on, vol.10, pp.53-65,1991.
[50]V. A. Stenger, et al., "Three-dimensional tailored RF pulses for the reduction of susceptibility artifacts in T*2-weighted functional MRI," Magnetic Resonance in Medicine, vol.44, pp.525-531,2000.
[51]S. Saekho, et al., "Small tip angle three-dimensional tailored radiofrequency slab-select pulse for reduced B1 inhomogeneity at 3 T," Magnetic Resonance in Medicine, vol.53, pp.479-484,2005.
[52]P. C. Hansen, "Regularization Tools-a Matlab package for analysis and solution of discrete ill-posed problems," Dept. of Mathematical Modeling, Technical University of Denmark 1998.
[53]D. Xu, et al., "Variable slew-rate spiral design:Theory and application to peak B1 amplitude reduction in 2D RF pulse design," Magnetic Resonance in Medicine, vol. 58, pp.835-842,2007.
[54]S. Conolly, et al., "Variable-rate selective excitation," Journal of Magnetic Resonance (1969), vol.78, pp.440-458,1988.
[55]L. Daeho, et al., "Time-optimal design for multidimensional and parallel transmit variable-rate selective excitation," Magnetic Resonance in Medicine, vol.61, pp. 1471-1479,2009.
[56]F. Liu and S. Crozier, "Electromagnetic fields inside a lossy, multilayered spherical head phantom excited by MRI coils:models and methods," Physics in Medicine and Biology, vol.49, p.1835,2004.
[57]A. Takahashi and T. Peters, "Compensation of multi-dimensional selective excitation pulses using measured k-space trajectories," Magnetic Resonance in Medicine, vol. 34, pp.446-456,1995.
[58]M. T. Alley, et al., "Gradient characterization using a Fourier-transform technique," Magnetic Resonance in Medicine, vol.39, pp.581-587,1998.
[59]X. Wu, et al., "Parallel excitation in the human brain at 9.4 T counteracting k-space errors with RF pulse design," Magnetic Resonance in Medicine, vol.63, pp.524-529, 2010.
[60]D. K. Sodickson and W. J. Manning, "Simultaneous acquisition of spatial harmonics (SMASH):Fast imaging with radiofrequency coil arrays," Magnetic Resonance in Medicine, vol.38, pp.591-603,1997.
[61]K. P. Pruessmann, et al., "SENSE:Sensitivity encoding for fast MRI," Magnetic Resonance in Medicine, vol.42, pp.952-962,1999.
[62]M. A. Griswold, et al., "Generalized autocalibrating partially parallel acquisitions (GRAPPA)," Magnetic Resonance in Medicine, vol.47, pp.1202-1210,2002.
[63]F. Wiesinger, et al., "Parallel imaging performance as a function of field strength—An experimental investigation using electrodynamic scaling," Magnetic Resonance in Medicine, vol.52, pp.953-964,2004.
[64]J. A. de Zwart, et al., "Design of a SENSE-optimized high-sensitivity MRI receive coil for brain imaging," Magnetic Resonance in Medicine, vol.47, pp.1218-1227, 2002.
[65]M. Weiger, et al., "Specific coil design for SENSE:A six-element cardiac array," Magnetic Resonance in Medicine, vol.45, pp.495-504,2001.
[66]D. K. Sodickson, "Tailored SMASH image reconstructions for robust in vivo parallel MR imaging," Magnetic Resonance in Medicine, vol.44, pp.243-251,2000.
[67]K. M. P. H. Chan, B. Anderson, "Diagonal-Arranged Quadrature Coil Arrays for 3D SENSE Imaging," in Proc 11th Annual Meeting ISMRM, Kyoto,2004.
[68]J. S. Nolwenn Caillet, Leo Tam, Gigi Galiana, R. Todd Constable, "The Twisted coil: A New Strip Array Coil Topology for 3D SENSE," in Proc 20th Annual Meeting ISMRM, Melbourne,2012, p.3355.
[69]G. Chen, et al., "An optimization method for designing SENSE imaging RF coil arrays," Journal of Magnetic Resonance, vol.186, pp.273-281,2007.
[70]J. D. Willig-Onwuachi, et al., "Designer RF field profiles for parallel imaging applications," Concepts in Magnetic Resonance Part B:Magnetic Resonance Engineering, vol.27B, pp.75-85,2005.
[71]M. Weiger, et al., "2D sense for faster 3D MRI," Magnetic Resonance Materials in Physics, Biology and Medicine, vol.14, pp.10-19,2002.
[72]M. Buehrer, et al., "Coil setup optimization for 2D-SENSE whole-heart coronary imaging," Magnetic Resonance in Medicine, vol.55, pp.460-464,2006.
[73]L. T. Muftuler, et al., "An inverse method to design RF coil arrays optimized for SENSE imaging," Physics in Medicine and Biology, vol.51, p.6457,2006.
[74]G. C. Wiggins, et al., "96-Channel receive-only head coil for 3 Tesla:Design optimization and evaluation," Magnetic Resonance in Medicine, vol.62, pp.754-762, 2009.
[75]T. Niendorf and D. Sodickson, "Highly accelerated cardiovascular MR imaging using many channel technology:concepts and clinical applications," European Radiology, vol.18, pp.87-102,2008.
[76]C. J. Hardy, et al., "128-channel body MRI with a flexible high-density receiver-coil array," Journal of Magnetic Resonance Imaging, vol.28, pp.1219-1225,2008.
[77]G. C. Wiggins, et al., "32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry," Magnetic Resonance in Medicine, vol.56, pp. 216-223,2006.
[78]C. J. Hardy, et al., "32-element receiver-coil array for cardiac imaging," Magnetic Resonance in Medicine, vol.55, pp.1142-1149,2006.
[79]M. P. McDougall and S. M. Wright, "64-channel array coil for single echo acquisition magnetic resonance imaging," Magnetic Resonance in Medicine, vol.54, pp.386-392, 2005.
[80]Y. Zhu, et al., "Highly parallel volumetric imaging with a 32-element RF coil array," Magnetic Resonance in Medicine, vol.52, pp.869-877,2004.
[81]N. D. Z. F. Wiesinger, K. P. Pruessmann, "Approaching Ultimate SNR with Finite Coil Arrays," in Proc 13th Annual Meeting ISMRM, Miami Beach,2005, p.672.
[82]M. A. Dieringer, et al., "Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T," Journal of Magnetic Resonance Imaging, vol.33, pp.736-741,2011.
[83]A. Kumar, et al., "Noise figure limits for circular loop MR coils," Magnetic Resonance in Medicine, vol.61, pp.1201-1209,2009.
[84]R. A. Lemdiasov, et al., "A numerical postprocessing procedure for analyzing radio frequency MRI coils," Concepts in Magnetic Resonance Part A, vol.38A, pp. 133-147,2011.
[85]N. Avdievich, "Transceiver-Phased Arrays for Human Brain Studies at 7 T," Applied Magnetic Resonance, vol.41, pp.483-506,2011.
[86]A. Graβ1, et al., "Design, evaluation and application of an eight channel transmit/receive coil array for cardiac MRI at 7.0 T," European Journal of Radiology, in press.
[87]C. J. Snyder, et al., "Comparison between eight- and sixteen-channel TEM transceive arrays for body imaging at 7 T," Magnetic Resonance in Medicine, vol.67, pp. 954-964,2012.
[88]X. Zhang, et al., "Higher-order harmonic transmission-line RF coil design for MR applications," Magnetic Resonance in Medicine, vol.53, pp.1234-1239,2005.
[89]G. Adriany, et al., "A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 Tesla," Magnetic Resonance in Medicine, vol.59, pp.590-597,2008.
[90]N. I. Avdievich and H. P. Hetherington, "High-field head radiofrequency volume coils using transverse electromagnetic (TEM) and phased array technologies," NMR in Biomedicine, vol.22, pp.960-974,2009.
[91]N.I. Avdievich, et al., "High-field actively detuneable transverse electromagnetic (TEM) coil with low-bias voltage for high-power RF transmission," Magnetic Resonance in Medicine, vol.57, pp.1190-1195,2007.
[92]A. Kumar and P. A. Bottomley, "Optimizing the intrinsic signal-to-noise ratio of MRI strip detectors," Magnetic Resonance in Medicine, vol.56, pp.157-166,2006.
[93]S. Orzada, et al., "Design and comparison of two eight-channel transmit/receive radiofrequency arrays for in vivo rodent imaging on a 7 T human whole-body MRI system," Medical Physics, vol.37, pp.2225-2232,2010.
[94]J. R. Hadley, et al., "Relative RF coil performance in carotid imaging," Magnetic Resonance Imaging, vol.23, pp.629-639,2005.
[95]S. M. Wright and L. L. Wald, "Theory and application of array coils in MR spectroscopy," NMR in Biomedicine, vol.10, pp.394-410,1997.
[96]P. A. Bottomley, et al., "What is the optimum phased array coil design for cardiac and torso magnetic resonance?," Magnetic Resonance in Medicine, vol.37, pp.591-599, 1997.
[97]P. Spincemaille, et al., "Optimal coil array design:the two-coil case," Magnetic Resonance Imaging, vol.25, pp.671-677,2007.
[98]P. Jehenson, et al., "Analytical method for the compensation of eddy-current effects induced by pulsed magnetic field gradients in NMR systems," Journal of Magnetic Resonance (1969), vol.90, pp.264-278,1990.
[99]N. G. Papadakis, et al., "A general method for measurement of the time integral of variant magnetic field gradients:Application to 2D spiral imaging," Magnetic Resonance Imaging, vol.15, pp.567-578,1997.
[100]M. Beaumont, et al., "Improved k-space trajectory measurement with signal shifting," Magnetic Resonance in Medicine, vol.58, pp.200-205,2007.
[101]M. A. Morich, et al., "Exact temporal eddy current compensation in magnetic resonance imaging systems," Medical Imaging, IEEE Transactions on, vol.7, pp. 247-254,1988.
[102]Q. Liu, et al., "Quantitative characterization of the eddy current fields in a 40-cm bore superconducting magnet," Magnetic Resonance in Medicine, vol.31, pp.73-76,1994.
[103]H. Tan and C. H. Meyer, "Estimation of k-space trajectories in spiral MRI," Magnetic Resonance in Medicine, vol.61, pp.1396-1404,2009.
[104]D. C. Peters, et al., "Centering the projection reconstruction trajectory:Reducing gradient delay errors," Magnetic Resonance in Medicine, vol.50, pp.1-6,2003.
[105]N. P. Davies and P. Jezzard, "Calibration of gradient propagation delays for accurate two-dimensional radiofrequency pulses," Magnetic Resonance in Medicine, vol.53, pp.231-236,2005.
[106]I. C. Atkinson, et al., "Characterization and correction of system delays and eddy currents for MR imaging with ultrashort echo-time and time-varying gradients," Magnetic Resonance in Medicine, vol.62, pp.532-537,2009.
[107]R. K. Robison, et al., "Fast, simple gradient delay estimation for spiral MRI," Magnetic Resonance in Medicine, vol.63, pp.1683-1690,2010.
[108]T. F. R. Speier P, "Robust radial imaging with predetermined isotropic gradient delay correction," presented at the Proc 14th Annual Meeting ISMRM, Seattle,2006.
[109]P. Latta, et al., "Simple phase method for measurement of magnetic field gradient waveforms," Magnetic Resonance Imaging, vol.25, pp.1272-1276,2007.
[2]Y. Zhu, "Parallel excitation with an array of transmit coils," Magnetic Resonance in Medicine, vol.51, pp.775-784,2004.
[3]W. Grissom, et al., "Spatial domain method for the design of RF pulses in multicoil parallel excitation," Magnetic Resonance in Medicine, vol.56, pp.620-629,2006.
[4]K. Setsompop, et al., "Parallel RF transmission with eight channels at 3 Tesla," Magnetic Resonance in Medicine, vol.56, pp.1163-1171,2006.
[5]D. Xu, et al., "A noniterative method to design large-tip-angle multidimensional spatially-selective radio frequency pulses for parallel transmission," Magnetic Resonance in Medicine, vol.58, pp.326-334,2007.
[6]W. A. Grissom, et al., "Additive angle method for fast large-tip-angle RF pulse design in parallel excitation," Magnetic Resonance in Medicine, vol.59, pp.779-787,2008.
[7]D. Xu, et al., "Designing multichannel, multidimensional, arbitrary flip angle RF pulses using an optimal control approach," Magnetic Resonance in Medicine, vol.59, pp.547-560,2008.
[8]W. A. Grissom, et al., "Fast Large-Tip-Angle Multidimensional and Parallel RF Pulse Design in MRI," Medical Imaging, IEEE Transactions on, vol.28, pp.1548-1559, 2009.
[9]J. L. Ulloa, et al., "Exploring 3D RF shimming for slice selective imaging," in Proceedings of the 13th Annual Meeting of ISMRM, Miami Beach, FL, USA,2005, p. 21.
[10]Z. Zhang, et al., "Reduction of transmitter B1 inhomogeneity with transmit SENSE slice-select pulses," Magnetic Resonance in Medicine, vol.57, pp.842-847,2007.
[11]K. Setsompop, et al., "Slice-selective RF pulses for in vivo B1+ inhomogeneity mitigation at 7 tesla using parallel RF excitation with a 16-element coil," Magnetic Resonance in Medicine, vol.60, pp.1422-1432,2008.
[12]A. C. Zelinski, et al., "Sparsity-Enforced Slice-Selective MRI RF Excitation Pulse Design," Medical Imaging, IEEE Transactions on, vol.27, pp.1213-1229,2008.
[13]C.-Y. Yip, et al., "Joint design of trajectory and RF pulses for parallel excitation," Magnetic Resonance in Medicine, vol.58, pp.598-604,2007.
[14]C. Ma, et al., "Joint design of spoke trajectories and RF pulses for parallel excitation," Magnetic Resonance in Medicine, pp. n/a-n/a,2010.
[15]C. y. Yip, et al., "Advanced three-dimensional tailored RF pulse for signal recovery in T2*-weighted functional magnetic resonance imaging," Magnetic Resonance in Medicine, vol.56, pp.1050-1059,2006.
[16]G. T. Luk-Pat, et al., "High-resolution three-dimensional in vivo imaging of atherosclerotic plaque," Magnetic Resonance in Medicine, vol.42, pp.762-771,1999.
[17]G. Yang, et al., "Locally focused 3D coronary imaging using volume-selective RF excitation," Magnetic Resonance in Medicine, vol.41, pp.171-178,1999.
[18]L. A. Crowe, et al., "Volume-selective 3D turbo spin echo imaging for vascular wall imaging and distensibility measurement," Journal of Magnetic Resonance Imaging, vol.17, pp.572-580,2003.
[19]M. Stuber, et al., "Selective three-dimensional visualization of the coronary arterial lumen using arterial spin tagging," Magnetic Resonance in Medicine, vol.47, pp. 322-329,2002.
[20]D. C. Alsop and J. A. Detre, "Multisection cerebral blood flow MR imaging with continuous arterial spin labeling," Radiology, vol.208, pp.410-416, August 1,1998 1998.
[21]J. P. Mugler, et al., "Optimized Single-Slab Three-dimensional Spin-Echo MR Imaging of the Brain," Radiology, vol.216, pp.891-899,2000.
[22]P. J. W. Pouwels, et al., "Human Gray Matter:Feasibility of Single-Slab 3D Double Inversion-Recovery High-Spatial-Resolution MR Imaging," Radiology, vol.241, pp. 873-879,2006.
[23]B. Moraal, et al., "Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis," European Radiology, vol.18, pp.2311-2320,2008.
[24]K.-N. K. N. Darji, G. Patel, H-P. Fautz, J. Bernarding, O. Speck, "Evaluating further benefits of B1+ homogenity when more transmit chnnels are used," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p.324.
[25]J. W. P. N. I. Avdievich, H. P. Hetherington, "Improved longitudinal coverage for human brain at 7T:A 16 Element Transceiver Array," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p.328.
[26]N. I. A. H. P. Hetherington, and J. W. Pan, "Multiplexed RF Transmission for Transceiver Arrays at 7T," in Proc 19th Annual Meeting ISMRM, Montreal,2011, p. 163.
[27]P. Mansfield and B. Chapman, "Active magnetic screening of coils for static and time-dependent magnetic field generation in NMR imaging," Journal of Physics E: Scientific Instruments, vol.19, p.540,1986.
[28]H. M. Gach, et al., "A programmable pre-emphasis system," Magnetic Resonance in Medicine, vol.40, pp.427-431,1998.
[29]R. E. Wysong, et al., "A novel eddy current compensation scheme for pulsed gradient systems," Magnetic Resonance in Medicine, vol.31, pp.572-575,1994.
[30]F. Calamante, et al., "Correction for eddy current induced Bo shifts in diffusion-weighted echo-planar imaging," Magnetic Resonance in Medicine, vol.41, pp.95-102,1999.
[31]N. G. Papadakis, et al., "Gradient preemphasis calibration in diffusion-weighted echo-planar imaging," Magnetic Resonance in Medicine, vol.44, pp.616-624,2000.
[32]A. L. Alexander, et al., "Elimination of eddy current artifacts in diffusion-weighted echo-planar images:The use of bipolar gradients," Magnetic Resonance in Medicine, vol.38, pp.1016-1021,1997.
[33]X. J. Zhou, et al., "Artifacts induced by concomitant magnetic field in fast spin-echo imaging," Magnetic Resonance in Medicine, vol.40, pp.582-591,1998.
[34]C. B. Ahn and Z. H. Cho, "Analysis of eddy currents in nuclear magnetic resonance imaging," Magnetic Resonance in Medicine, vol.17, pp.149-163,1991.
[35]T. G. Reese, et al., "Reduction of eddy-current-induced distortion in diffusion MRI using a twice-refocused spin echo," Magnetic Resonance in Medicine, vol.49, pp. 177-182,2003.
[36]D. M. Spielman and J. M. Pauly, "Spiral imaging on a small-bore system at 4.7t," Magnetic Resonance in Medicine, vol.34, pp.580-585,1995.
[37]T. Onodera, et al., "A method of measuring field-gradient modulation shapes. Application to high-speed NMR spectroscopic imaging," Journal of Physics E: Scientific Instruments, vol.20, p.416,1987.
[38]G. F. Mason, et al., "A Method to measure arbitrary k-space trajectories for rapid MR imaging," Magnetic Resonance in Medicine, vol.38, pp.492-496,1997.
[39]Y. Zhang, et al., "A novel k-space trajectory measurement technique," Magnetic Resonance in Medicine, vol.39, pp.999-1004,1998.
[40]J. H. Duyn, et al., "Simple Correction Method fork-Space Trajectory Deviations in MRI," Journal of Magnetic Resonance, vol.132, pp.150-153,1998.
[41]B. C. Pruessmann KP, De Zanche N, "Magnetic field monitoring during MRI acquisition improves image reconstruction," presented at the Proc 13th Annual Meeting ISMRM, Miami Beach,2005.
[42]B. C. De Zanche N, Massner JA, Pruessmann KP, "Advances in NMR probe technology for magnetic field monitoring," presented at the Proc 14th Annual Meeting ISMRM, Seattle,2006.
[43]C. Barmet, et al., "Spatiotemporal magnetic field monitoring for MR," Magnetic-Resonance in Medicine, vol.60, pp.187-197,2008.
[44]P. Sipila, et al., "Robust, susceptibility-matched NMR probes for compensation of magnetic field imperfections in magnetic resonance imaging (MRI)," Sensors and Actuators A:Physical, vol.145-146, pp.139-146,2008.
[45]K. K. Bernstein MA, Zhou ZJ, Handbook of MRI pulse sequences. Boston:Academic Press,2004.
[46]J. Pauly, et al., "A k-space analysis of small-tip-angle excitation," Journal of Magnetic Resonance (1969), vol.81, pp.43-56,1989.
[47]S. Saekho, et al., "Fast-kz three-dimensional tailored radiofrequency pulse for reduced B1 inhomogeneity," Magnetic Resonance in Medicine, vol.55, pp.719-724, 2006.
[48]J. M. Pauly, et al., "A three-dimensional spin-echo or inversion pulse," Magnetic Resonance in Medicine, vol.29, pp.2-6,1993.
[49]J. Pauly, et al., "Parameter relations for the Shinnar-Le Roux selective excitation pulse design algorithm [NMR imaging]," Medical Imaging, IEEE Transactions on, vol.10, pp.53-65,1991.
[50]V. A. Stenger, et al., "Three-dimensional tailored RF pulses for the reduction of susceptibility artifacts in T*2-weighted functional MRI," Magnetic Resonance in Medicine, vol.44, pp.525-531,2000.
[51]S. Saekho, et al., "Small tip angle three-dimensional tailored radiofrequency slab-select pulse for reduced B1 inhomogeneity at 3 T," Magnetic Resonance in Medicine, vol.53, pp.479-484,2005.
[52]P. C. Hansen, "Regularization Tools-a Matlab package for analysis and solution of discrete ill-posed problems," Dept. of Mathematical Modeling, Technical University of Denmark 1998.
[53]D. Xu, et al., "Variable slew-rate spiral design:Theory and application to peak B1 amplitude reduction in 2D RF pulse design," Magnetic Resonance in Medicine, vol. 58, pp.835-842,2007.
[54]S. Conolly, et al., "Variable-rate selective excitation," Journal of Magnetic Resonance (1969), vol.78, pp.440-458,1988.
[55]L. Daeho, et al., "Time-optimal design for multidimensional and parallel transmit variable-rate selective excitation," Magnetic Resonance in Medicine, vol.61, pp. 1471-1479,2009.
[56]F. Liu and S. Crozier, "Electromagnetic fields inside a lossy, multilayered spherical head phantom excited by MRI coils:models and methods," Physics in Medicine and Biology, vol.49, p.1835,2004.
[57]A. Takahashi and T. Peters, "Compensation of multi-dimensional selective excitation pulses using measured k-space trajectories," Magnetic Resonance in Medicine, vol. 34, pp.446-456,1995.
[58]M. T. Alley, et al., "Gradient characterization using a Fourier-transform technique," Magnetic Resonance in Medicine, vol.39, pp.581-587,1998.
[59]X. Wu, et al., "Parallel excitation in the human brain at 9.4 T counteracting k-space errors with RF pulse design," Magnetic Resonance in Medicine, vol.63, pp.524-529, 2010.
[60]D. K. Sodickson and W. J. Manning, "Simultaneous acquisition of spatial harmonics (SMASH):Fast imaging with radiofrequency coil arrays," Magnetic Resonance in Medicine, vol.38, pp.591-603,1997.
[61]K. P. Pruessmann, et al., "SENSE:Sensitivity encoding for fast MRI," Magnetic Resonance in Medicine, vol.42, pp.952-962,1999.
[62]M. A. Griswold, et al., "Generalized autocalibrating partially parallel acquisitions (GRAPPA)," Magnetic Resonance in Medicine, vol.47, pp.1202-1210,2002.
[63]F. Wiesinger, et al., "Parallel imaging performance as a function of field strength—An experimental investigation using electrodynamic scaling," Magnetic Resonance in Medicine, vol.52, pp.953-964,2004.
[64]J. A. de Zwart, et al., "Design of a SENSE-optimized high-sensitivity MRI receive coil for brain imaging," Magnetic Resonance in Medicine, vol.47, pp.1218-1227, 2002.
[65]M. Weiger, et al., "Specific coil design for SENSE:A six-element cardiac array," Magnetic Resonance in Medicine, vol.45, pp.495-504,2001.
[66]D. K. Sodickson, "Tailored SMASH image reconstructions for robust in vivo parallel MR imaging," Magnetic Resonance in Medicine, vol.44, pp.243-251,2000.
[67]K. M. P. H. Chan, B. Anderson, "Diagonal-Arranged Quadrature Coil Arrays for 3D SENSE Imaging," in Proc 11th Annual Meeting ISMRM, Kyoto,2004.
[68]J. S. Nolwenn Caillet, Leo Tam, Gigi Galiana, R. Todd Constable, "The Twisted coil: A New Strip Array Coil Topology for 3D SENSE," in Proc 20th Annual Meeting ISMRM, Melbourne,2012, p.3355.
[69]G. Chen, et al., "An optimization method for designing SENSE imaging RF coil arrays," Journal of Magnetic Resonance, vol.186, pp.273-281,2007.
[70]J. D. Willig-Onwuachi, et al., "Designer RF field profiles for parallel imaging applications," Concepts in Magnetic Resonance Part B:Magnetic Resonance Engineering, vol.27B, pp.75-85,2005.
[71]M. Weiger, et al., "2D sense for faster 3D MRI," Magnetic Resonance Materials in Physics, Biology and Medicine, vol.14, pp.10-19,2002.
[72]M. Buehrer, et al., "Coil setup optimization for 2D-SENSE whole-heart coronary imaging," Magnetic Resonance in Medicine, vol.55, pp.460-464,2006.
[73]L. T. Muftuler, et al., "An inverse method to design RF coil arrays optimized for SENSE imaging," Physics in Medicine and Biology, vol.51, p.6457,2006.
[74]G. C. Wiggins, et al., "96-Channel receive-only head coil for 3 Tesla:Design optimization and evaluation," Magnetic Resonance in Medicine, vol.62, pp.754-762, 2009.
[75]T. Niendorf and D. Sodickson, "Highly accelerated cardiovascular MR imaging using many channel technology:concepts and clinical applications," European Radiology, vol.18, pp.87-102,2008.
[76]C. J. Hardy, et al., "128-channel body MRI with a flexible high-density receiver-coil array," Journal of Magnetic Resonance Imaging, vol.28, pp.1219-1225,2008.
[77]G. C. Wiggins, et al., "32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry," Magnetic Resonance in Medicine, vol.56, pp. 216-223,2006.
[78]C. J. Hardy, et al., "32-element receiver-coil array for cardiac imaging," Magnetic Resonance in Medicine, vol.55, pp.1142-1149,2006.
[79]M. P. McDougall and S. M. Wright, "64-channel array coil for single echo acquisition magnetic resonance imaging," Magnetic Resonance in Medicine, vol.54, pp.386-392, 2005.
[80]Y. Zhu, et al., "Highly parallel volumetric imaging with a 32-element RF coil array," Magnetic Resonance in Medicine, vol.52, pp.869-877,2004.
[81]N. D. Z. F. Wiesinger, K. P. Pruessmann, "Approaching Ultimate SNR with Finite Coil Arrays," in Proc 13th Annual Meeting ISMRM, Miami Beach,2005, p.672.
[82]M. A. Dieringer, et al., "Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T," Journal of Magnetic Resonance Imaging, vol.33, pp.736-741,2011.
[83]A. Kumar, et al., "Noise figure limits for circular loop MR coils," Magnetic Resonance in Medicine, vol.61, pp.1201-1209,2009.
[84]R. A. Lemdiasov, et al., "A numerical postprocessing procedure for analyzing radio frequency MRI coils," Concepts in Magnetic Resonance Part A, vol.38A, pp. 133-147,2011.
[85]N. Avdievich, "Transceiver-Phased Arrays for Human Brain Studies at 7 T," Applied Magnetic Resonance, vol.41, pp.483-506,2011.
[86]A. Graβ1, et al., "Design, evaluation and application of an eight channel transmit/receive coil array for cardiac MRI at 7.0 T," European Journal of Radiology, in press.
[87]C. J. Snyder, et al., "Comparison between eight- and sixteen-channel TEM transceive arrays for body imaging at 7 T," Magnetic Resonance in Medicine, vol.67, pp. 954-964,2012.
[88]X. Zhang, et al., "Higher-order harmonic transmission-line RF coil design for MR applications," Magnetic Resonance in Medicine, vol.53, pp.1234-1239,2005.
[89]G. Adriany, et al., "A geometrically adjustable 16-channel transmit/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 Tesla," Magnetic Resonance in Medicine, vol.59, pp.590-597,2008.
[90]N. I. Avdievich and H. P. Hetherington, "High-field head radiofrequency volume coils using transverse electromagnetic (TEM) and phased array technologies," NMR in Biomedicine, vol.22, pp.960-974,2009.
[91]N.I. Avdievich, et al., "High-field actively detuneable transverse electromagnetic (TEM) coil with low-bias voltage for high-power RF transmission," Magnetic Resonance in Medicine, vol.57, pp.1190-1195,2007.
[92]A. Kumar and P. A. Bottomley, "Optimizing the intrinsic signal-to-noise ratio of MRI strip detectors," Magnetic Resonance in Medicine, vol.56, pp.157-166,2006.
[93]S. Orzada, et al., "Design and comparison of two eight-channel transmit/receive radiofrequency arrays for in vivo rodent imaging on a 7 T human whole-body MRI system," Medical Physics, vol.37, pp.2225-2232,2010.
[94]J. R. Hadley, et al., "Relative RF coil performance in carotid imaging," Magnetic Resonance Imaging, vol.23, pp.629-639,2005.
[95]S. M. Wright and L. L. Wald, "Theory and application of array coils in MR spectroscopy," NMR in Biomedicine, vol.10, pp.394-410,1997.
[96]P. A. Bottomley, et al., "What is the optimum phased array coil design for cardiac and torso magnetic resonance?," Magnetic Resonance in Medicine, vol.37, pp.591-599, 1997.
[97]P. Spincemaille, et al., "Optimal coil array design:the two-coil case," Magnetic Resonance Imaging, vol.25, pp.671-677,2007.
[98]P. Jehenson, et al., "Analytical method for the compensation of eddy-current effects induced by pulsed magnetic field gradients in NMR systems," Journal of Magnetic Resonance (1969), vol.90, pp.264-278,1990.
[99]N. G. Papadakis, et al., "A general method for measurement of the time integral of variant magnetic field gradients:Application to 2D spiral imaging," Magnetic Resonance Imaging, vol.15, pp.567-578,1997.
[100]M. Beaumont, et al., "Improved k-space trajectory measurement with signal shifting," Magnetic Resonance in Medicine, vol.58, pp.200-205,2007.
[101]M. A. Morich, et al., "Exact temporal eddy current compensation in magnetic resonance imaging systems," Medical Imaging, IEEE Transactions on, vol.7, pp. 247-254,1988.
[102]Q. Liu, et al., "Quantitative characterization of the eddy current fields in a 40-cm bore superconducting magnet," Magnetic Resonance in Medicine, vol.31, pp.73-76,1994.
[103]H. Tan and C. H. Meyer, "Estimation of k-space trajectories in spiral MRI," Magnetic Resonance in Medicine, vol.61, pp.1396-1404,2009.
[104]D. C. Peters, et al., "Centering the projection reconstruction trajectory:Reducing gradient delay errors," Magnetic Resonance in Medicine, vol.50, pp.1-6,2003.
[105]N. P. Davies and P. Jezzard, "Calibration of gradient propagation delays for accurate two-dimensional radiofrequency pulses," Magnetic Resonance in Medicine, vol.53, pp.231-236,2005.
[106]I. C. Atkinson, et al., "Characterization and correction of system delays and eddy currents for MR imaging with ultrashort echo-time and time-varying gradients," Magnetic Resonance in Medicine, vol.62, pp.532-537,2009.
[107]R. K. Robison, et al., "Fast, simple gradient delay estimation for spiral MRI," Magnetic Resonance in Medicine, vol.63, pp.1683-1690,2010.
[108]T. F. R. Speier P, "Robust radial imaging with predetermined isotropic gradient delay correction," presented at the Proc 14th Annual Meeting ISMRM, Seattle,2006.
[109]P. Latta, et al., "Simple phase method for measurement of magnetic field gradient waveforms," Magnetic Resonance Imaging, vol.25, pp.1272-1276,2007.