脉冲序列
磁场
核磁共振
磁共振成像
信号(编程语言)
领域(数学)
电流(流体)
电流密度
旋转(数学)
编码(内存)
物理
脉搏(音乐)
计算物理学
计算机科学
电压
数学
人工智能
医学
量子力学
纯数学
放射科
程序设计语言
热力学
作者
Panu T. Vesanen,Jaakko O. Nieminen,Koos C. J. Zevenhoven,Yi‐Cheng Hsu,Risto J. Ilmoniemi
标识
DOI:10.1016/j.mri.2014.01.012
摘要
Electric current density can be measured noninvasively with magnetic resonance imaging (MRI). Determining all three components of the current density, however, requires physical rotation of the sample or current injection from several directions when done with conventional methods. However, the emerging technology of ultra-low-field (ULF) MRI, in which the signal encoding and acquisition is conducted at a microtesla-range magnetic field, offers new possibilities. The low applied magnetic fields can even be switched off completely within the pulse sequence, increasing the flexibility of the available sequences. In this article, we present a ULF-MRI sequence designed for obtaining all three components of a current-density pattern without the need of sample rotations. The sequence consists of three steps: prepolarization of the sample, signal encoding in the current-density-associated magnetic field without applying any MRI fields, and spatial encoding in a microtesla-range field using any standard ULF-MRI sequence. The performance of the method is evaluated by numerical simulations. The method may find applications, e.g., in noninvasive conductivity imaging of tissue.
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