title: Current-induced alternating reversed dual-echo-steady-state for joint estimation of tissue relaxation and electrical properties.
abstract: To develop a current-induced, alternating reversed dual-echo-steady-state-based magnetic resonance electrical impedance tomography for joint estimation of tissue relaxation and electrical properties.
  
  
  
  The proposed method reverses the readout gradient configuration of conventional, in which steady-state-free-precession (SSFP)-ECHO is produced earlier than SSFP-free-induction-decay (FID) while alternating current pulses are applied in between the two SSFPs to secure high sensitivity of SSFP-FID to injection current. Additionally, alternating reversed dual-echo-steady-state signals are modulated by employing variable flip angles over two orthogonal injections of current pulses. Ratiometric signal models are analytically constructed, from which T1, T2, and current-induced Bzare jointly estimated by solving a nonlinear inverse problem for conductivity reconstruction. Numerical simulations and experimental studies are performed to investigate the feasibility of the proposed method in estimating relaxation parameters and conductivity.
  
  
  
  The proposed method, if compared with conventional magnetic resonance electrical impedance tomography, enables rapid data acquisition and simultaneous estimation of T1, T2, and current-induced Bz, yielding a comparable level of signal-to-noise ratio in the parameter estimates while retaining a relative conductivity contrast.
  
  
  
  We successfully demonstrated the feasibility of the proposed method in jointly estimating tissue relaxation parameters as well as conductivity distributions. It can be a promising, rapid imaging strategy for quantitative conductivity estimation. Magn Reson Med 78:107-120, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Biomedical Imaging and Engineering Lab, Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
authors.forename: Hyunyeol
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
authors.affiliation: Biomedical Imaging and Engineering Lab, Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
authors.forename: Jaeseok
authors.initials: J
authors.lastname: Park
mesh_terms: D000465:Algorithms; D003217:Conductometry / Q000379:methods*; D017097:Electric Impedance; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D010992:Plethysmography, Impedance / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: alternating steady-state-free-precession; conductivity; dual-echo-steady-state; magnetic resonance imaging; relaxation