Lee Hyunyeol, Sohn Chul-Ho, Park Jaeseok
Biomedical Imaging and Engineering Lab, Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea.
Magn Reson Med. 2017 Jul;78(1):107-120. doi: 10.1002/mrm.26350. Epub 2016 Aug 4.
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 T , T , and current-induced B are 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 T , T , and current-induced B , 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.
开发一种基于电流感应、交替反转双回波稳态的磁共振电阻抗断层成像技术，用于联合估计组织弛豫和电学特性。
所提出的方法反转了传统的读出梯度配置，其中稳态自由进动（SSFP）回波比稳态自由感应衰减（FID）更早产生，同时在两个SSFP之间施加交流脉冲以确保SSFP-FID对注入电流具有高灵敏度。此外，通过在两个正交的电流脉冲注入中采用可变翻转角来调制交替反转双回波稳态信号。解析构建比例信号模型，通过求解用于电导率重建的非线性逆问题来联合估计T1、T2和电流感应的B0。进行了数值模拟和实验研究，以研究所提出方法在估计弛豫参数和电导率方面的可行性。
与传统的磁共振电阻抗断层成像相比，所提出的方法能够快速采集数据并同时估计T1、T2和电流感应的B0，在参数估计中产生相当水平的信噪比，同时保持相对电导率对比度。
我们成功证明了所提出方法在联合估计组织弛豫参数以及电导率分布方面的可行性。它可以成为一种有前途的、用于定量电导率估计的快速成像策略。《磁共振医学》78:107 - 120, 2017。© 2016国际磁共振医学学会。
