Simultaneous use of linear and nonlinear gradients for B1 + inhomogeneity correction
buir.contributor.author | Atalar, Ergin | |
dc.citation.epage | 15 | en_US |
dc.citation.issueNumber | 9 | en_US |
dc.citation.spage | 1 | en_US |
dc.citation.volumeNumber | 30 | en_US |
dc.contributor.author | Ertan, K. | en_US |
dc.contributor.author | Atalar, Ergin | en_US |
dc.date.accessioned | 2018-04-12T10:38:44Z | |
dc.date.available | 2018-04-12T10:38:44Z | |
dc.date.issued | 2017 | en_US |
dc.department | National Magnetic Resonance Research Center (UMRAM) | en_US |
dc.department | Department of Electrical and Electronics Engineering | en_US |
dc.description.abstract | The simultaneous use of linear spatial encoding magnetic fields (L-SEMs) and nonlinear spatial encoding magnetic fields (N-SEMs) in B1 + inhomogeneity problems is formulated and demonstrated with both simulations and experiments. Independent excitation k-space variables for N-SEMs are formulated for the simultaneous use of L-SEMs and N-SEMs by assuming a small tip angle. The formulation shows that, when N-SEMs are considered as an independent excitation k-space variable, numerous different k-space trajectories and frequency weightings differing in dimension, length, and energy can be designed for a given target transverse magnetization distribution. The advantage of simultaneous use of L-SEMs and N-SEMs is demonstrated by B1 + inhomogeneity correction with spoke excitation. To fully utilize the independent k-space formulations, global optimizations are performed for 1D, 2D RF power limited, and 2D RF power unlimited simulations and experiments. Three different cases are compared: L-SEMs alone, N-SEMs alone, and both used simultaneously. In all cases, the simultaneous use of L-SEMs and N-SEMs leads to a decreased standard deviation in the ROI compared with using only L-SEMs or N-SEMs. The simultaneous use of L-SEMs and N-SEMs results in better B1 + inhomogeneity correction than using only L-SEMs or N-SEMs due to the increased number of degrees of freedom. | en_US |
dc.description.provenance | Made available in DSpace on 2018-04-12T10:38:44Z (GMT). No. of bitstreams: 1 bilkent-research-paper.pdf: 179475 bytes, checksum: ea0bedeb05ac9ccfb983c327e155f0c2 (MD5) Previous issue date: 2017 | en |
dc.embargo.release | 2019-08-15 | en_US |
dc.identifier.doi | 10.1002/nbm.3742 | en_US |
dc.identifier.issn | 0952-3480 | |
dc.identifier.uri | http://hdl.handle.net/11693/36403 | |
dc.language.iso | English | en_US |
dc.publisher | John Wiley and Sons Ltd | en_US |
dc.relation.isversionof | http://dx.doi.org/10.1002/nbm.3742 | en_US |
dc.source.title | NMR in Biomedicine | en_US |
dc.subject | B1 + inhomogeneity | en_US |
dc.subject | Excitation k-space | en_US |
dc.subject | Nonlinear gradients | en_US |
dc.subject | Simultaneous use of linear and nonlinear gradients | en_US |
dc.subject | Small tip angle | en_US |
dc.subject | Spoke excitation | en_US |
dc.title | Simultaneous use of linear and nonlinear gradients for B1 + inhomogeneity correction | en_US |
dc.type | Article | en_US |