This article describes a method called Lorentz Force Electrical Impedance Tomography. The electrical conductivity of biological tissues can be measured through their sonication in a magnetic field: the vibration of the tissues inside the field induces an electrical current by Lorentz force. This current, detected by electrodes placed around the sample, is proportional to the ultrasonic pressure, to the strength of the magnetic field and to the electrical conductivity gradient along the acoustic axis. By focusing at different places inside the sample, a map of the electrical conductivity gradient can be established. In this study experiments were conducted on a gelatin phantom and on a beef sample, successively placed in a 300 mT magnetic field and sonicated with an ultrasonic transducer focused at 21 cm emitting 500 kHz bursts. Although all interfaces are not visible, in this exploratory study a good correlation is observed between the electrical conductivity image and the ultrasonic image. This method offers an alternative to detecting pathologies invisible to standard ultrasonography.
Applications of Lorentz force in medical acoustics: Lorentz force hydrophone, Lorentz Force Electrical Impedance Tomography, Imaging of shear waves induced by Lorentz force
Drive and measurement electrode patterns for electrode impedance tomography (EIT) imaging of neural activity in peripheral nerve
目的：建立周围神经神经活动EIT成像中几种驱动和测量模式的性能，其中涉及神经各向异性长度轴上的大阻抗变化。方法：使用周围神经的有限元（FE）四圆柱壳模型和32通道双环神经袖带比较了八种驱动和测量电极模式。FE模型的中心层包含代表神经活动的阻抗变化，在长度轴上为-0.3，在径向轴上为-8.8 x 10-4。电极图案中的四个产生垂直于各向异性轴延伸的纵向驱动电流。主要结果：横向电流模式比纵向模式产生更高的分辨率，但也更容易受到噪声和误差的影响，并且对中心样品位置的阻抗变化表现出更差的灵敏度。所考虑的四种纵向电流模式中的三种可以重建具有高达0.2 mV噪声和误差的束水平阻抗变化，其对应于归一化信号标准偏差的-5.5和+0.18 dB之间。在所有纵向电流模式中减小两个电极环之间的间距减小了样品的所有深度位置上的信号误差比。重要性：以各向异性长度轴上的大阻抗变化为目标的电极图案可以提供针对噪声和误差的改进的鲁棒性，这是朝向外周神经中的神经活动的实时EIT成像的关键步骤。
