Albert Jang1,2,3, Naoharu Kobayashi1, Steen Moeller1, J Thomas Vaughan1,2, Jianyi Zhang2,3, Michael Garwood4. 1. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minnesota, USA. 2. Department of Electrical and Computer Engineering, University of Minnesota, Minnesota, USA. 3. Department of Medicine, Cardiovascular Division, University of Minnesota, Minnesota, USA. 4. Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minnesota, USA. gar@cmrr.umn.edu.
Abstract
PURPOSE: To introduce a method of designing two-dimensional (2D) frequency-modulated pulses that produce phase coherence in a spatiotemporal manner. Uniquely, this class of pulses provides the ability to compensate for field inhomogeneity using a spatiotemporally dependent trajectory of maximum coherence in a single-shot. THEORY AND METHODS: A pulse design method based on a k-space description is developed. Bloch simulations and phantom experiments are used to demonstrate sequential spatiotemporal phase coherence and compensation for B1+ and B0 inhomogeneity. RESULTS: In the presence of modulated gradients, the 2D frequency-modulated pulses were shown to excite a cylinder in a selective manner. With a surface coil transmitter, compensation of the effect of B1+ inhomogeneity was experimentally verified, in agreement with simulation results. In addition, simulations were used to demonstrate partial compensation for B0 inhomogeneity. CONCLUSION: The 2D frequency-modulated pulses are a new class of pulses that generate phase coherence sequentially along a spatial trajectory determined by gradient- and frequency-modulated functions. By exploiting their spatiotemporal nature, 2D frequency-modulated pulses can compensate for spatial variation of the radiofrequency field in a single-shot excitation. Preliminary results shown suggest extensions might also be used to compensate for static field inhomogeneity. Magn Reson Med 76:1364-1374, 2016.
PURPOSE: To introduce a method of designing two-dimensional (2D) frequency-modulated pulses that produce phase coherence in a spatiotemporal manner. Uniquely, this class of pulses provides the ability to compensate for field inhomogeneity using a spatiotemporally dependent trajectory of maximum coherence in a single-shot. THEORY AND METHODS: A pulse design method based on a k-space description is developed. Bloch simulations and phantom experiments are used to demonstrate sequential spatiotemporal phase coherence and compensation for B1+ and B0 inhomogeneity. RESULTS: In the presence of modulated gradients, the 2D frequency-modulated pulses were shown to excite a cylinder in a selective manner. With a surface coil transmitter, compensation of the effect of B1+ inhomogeneity was experimentally verified, in agreement with simulation results. In addition, simulations were used to demonstrate partial compensation for B0 inhomogeneity. CONCLUSION: The 2D frequency-modulated pulses are a new class of pulses that generate phase coherence sequentially along a spatial trajectory determined by gradient- and frequency-modulated functions. By exploiting their spatiotemporal nature, 2D frequency-modulated pulses can compensate for spatial variation of the radiofrequency field in a single-shot excitation. Preliminary results shown suggest extensions might also be used to compensate for static field inhomogeneity. Magn Reson Med 76:1364-1374, 2016.
Authors: William Grissom; Chun-yu Yip; Zhenghui Zhang; V Andrew Stenger; Jeffrey A Fessler; Douglas C Noll Journal: Magn Reson Med Date: 2006-09 Impact factor: 4.668
Authors: Ryan Chamberlain; Jang-Yeon Park; Curt Corum; Essa Yacoub; Kamil Ugurbil; Clifford R Jack; Michael Garwood Journal: Magn Reson Med Date: 2007-10 Impact factor: 4.668
Authors: Angela L S Snyder; Curtis A Corum; Steen Moeller; Nathaniel J Powell; Michael Garwood Journal: Magn Reson Med Date: 2013-08-01 Impact factor: 4.668
Authors: Xiaoxuan He; M Arcan Ertürk; Andrea Grant; Xiaoping Wu; Russell L Lagore; Lance DelaBarre; Yiğitcan Eryaman; Gregor Adriany; Eddie J Auerbach; Pierre-François Van de Moortele; Kâmil Uğurbil; Gregory J Metzger Journal: Magn Reson Med Date: 2019-12-17 Impact factor: 4.668
Authors: Alex Gutierrez; Michael Mullen; Di Xiao; Albert Jang; Taylor Froelich; Michael Garwood; Jarvis Haupt Journal: IEEE Trans Med Imaging Date: 2021-08-31 Impact factor: 11.037