Yang Hua, Cook Greg G, Paley Martyn N J
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, United Kingdom.
Magn Reson Med. 2003 Sep;50(3):633-7. doi: 10.1002/mrm.10573.
A new method of estimating alternating currents using ghost images created when the magnetic field from a fluctuating current modulates the phase of the magnetic resonance (MR) signal between successive phase-encode views is described. The method, known as ghost reconstructed alternating current estimation (GRACE), may be useful for directly mapping fields, and hence current impulses produced by neuronal firing events when synchronized periodic modulation can be induced. Images were acquired on a 1.5 T MR system with small oil capsule phantoms and a single wire with an applied alternating current, placed perpendicular to the main field direction. Computer simulations of these experiments yielded ghost images that agreed with experimental results. A simulated ghost image resulting from an evoked neuronal waveform is also discussed. Weak magnetic fields were detected from both sinusoidal and square wave modulations.
描述了一种利用波动电流产生的磁场在连续相位编码视图之间调制磁共振（MR）信号相位时所创建的重影图像来估计交流电的新方法。该方法称为重影重建交流电估计（GRACE），当能够诱导同步周期性调制时，它可能有助于直接绘制磁场，从而绘制由神经元放电事件产生的电流脉冲。在1.5T MR系统上，使用小油囊体模和一根通有交流电且垂直于主磁场方向放置的单根导线采集图像。对这些实验的计算机模拟产生了与实验结果相符的重影图像。还讨论了由诱发神经元波形产生的模拟重影图像。从正弦波和方波调制中均检测到了弱磁场。
