Concomitant gradient terms in phase contrast MR: Analysis and correction Export

@article{PC Concomitant, abstract = {Whenever a linear gradient is activated, concomitant magnetic fields with non-linear spatial dependence result. This is a consequence of Maxwell's equations, i.e., within the imaging volume the magnetic field must have zero divergence, and has negligible curl. The concomitant, or Maxwell field has been described in the MRI literature for over 10 years. In this paper, we theoretically and experimentally show the existence of two additional lowest-order terms in the concomitant field, which we call cross-terms. The concomitant gradient cross-terms only arise when the longitudinal gradient Gz is simultaneously active with a transverse gradient (Gx or Gy). The effect of all of the concomitant gradient terms on phase contrast imaging is examined in detail. Several methods for reducing or eliminating phase errors arising from the concomitant magnetic field are described. The feasibility of a joint pulse sequence-reconstruction method, which requires no increase in minimum TE, is demonstrated. Since the lowest-order terms of the concomitant field are proportional to G2/B0, the importance of concomitant gradient terms is expected to increase given the current interest in systems with stronger gradients and/or weaker main magnetic fields.}, address = {GE Medical Systems, Waukesha, Wisconsin, Stanford University School of Medicine, Stanford, California; Department of Radiology, Lucas MRS Imaging Center, Stanford University School of Medicine, Stanford, California}, author = {Bernstein, Mat A. and Zhou, Xiaohong J. and Polzin, Jason A. and King, Kevin F. and Ganin, Alexander and Pelc, Norbert J. and Glover, Gary H.}, citeulike-article-id = {3345507}, citeulike-linkout-0 = {http://dx.doi.org/10.1002/mrm.1910390218}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/112214075/ABSTRACT}, doi = {10.1002/mrm.1910390218}, journal = {Magnetic Resonance in Medicine}, keywords = {2005, concomitant-fields, electrodynamics, mrm, phasecontrast, stanford}, number = {2}, pages = {300--308}, posted-at = {2008-09-27 20:24:13}, priority = {4}, title = {Concomitant gradient terms in phase contrast MR: Analysis and correction}, url = {http://dx.doi.org/10.1002/mrm.1910390218}, volume = {39}, year = {1998} }

TY - JOUR ID - PC Concomitant L3 - citeulike-article-id:3345507 N2 - Whenever a linear gradient is activated, concomitant magnetic fields with non-linear spatial dependence result. This is a consequence of Maxwell's equations, i.e., within the imaging volume the magnetic field must have zero divergence, and has negligible curl. The concomitant, or Maxwell field has been described in the MRI literature for over 10 years. In this paper, we theoretically and experimentally show the existence of two additional lowest-order terms in the concomitant field, which we call cross-terms. The concomitant gradient cross-terms only arise when the longitudinal gradient Gz is simultaneously active with a transverse gradient (Gx or Gy). The effect of all of the concomitant gradient terms on phase contrast imaging is examined in detail. Several methods for reducing or eliminating phase errors arising from the concomitant magnetic field are described. The feasibility of a joint pulse sequence-reconstruction method, which requires no increase in minimum TE, is demonstrated. Since the lowest-order terms of the concomitant field are proportional to G2/B0, the importance of concomitant gradient terms is expected to increase given the current interest in systems with stronger gradients and/or weaker main magnetic fields. IS - 2 JF - Magnetic Resonance in Medicine AD - GE Medical Systems, Waukesha, Wisconsin, Stanford University School of Medicine, Stanford, California; Department of Radiology, Lucas MRS Imaging Center, Stanford University School of Medicine, Stanford, California EP - 308 TI - Concomitant gradient terms in phase contrast MR: Analysis and correction VL - 39 SP - 300 KW - 2005 KW - concomitant-fields KW - electrodynamics KW - mrm KW - phasecontrast KW - stanford AU - Bernstein, Mat AU - Zhou, Xiaohong AU - Polzin, Jason AU - King, Kevin AU - Ganin, Alexander AU - Pelc, Norbert AU - Glover, Gary PY - 1998/// UR - http://dx.doi.org/10.1002/mrm.1910390218 ER -