Mattei Eugenio, Censi Federica, Triventi Michele, Napolitano Antonio, Genovese Elisabetta, Cannatà Vittorio, Calcagnini Giovanni
Department of Technology and Health, Italian National Institute of Health, Viale Regina Elena 299, 00161, Rome, Italy,
MAGMA. 2015 Jun;28(3):291-303. doi: 10.1007/s10334-014-0463-2. Epub 2014 Oct 11.
The gradient fields generated during magnetic resonance imaging (MRI) procedures have the potential to induce electrical current on implanted endocardial leads. Whether this current can result in undesired cardiac stimulation is unknown.
This paper provides a detailed description of how to construct an optically coupled sensor for the measurement of gradient-field-induced currents into endocardial leads. The system is based on a microcontroller that works as analog-to-digital converter and sends the current signal acquired from the lead to an optical high-speed, light-emitting diode transmitter. A plastic fiber guides the light outside the MRI chamber to a photodiode receiver and then to an acquisition board connected to a PC laptop.
The performance of the system has been characterized in terms of power consumption (8 mA on average), sampling frequency (20.5 kHz), measurement range (-12.8 to 10.3 mA) and resolution (22.6 µA). Results inside a 3 T MRI scanner are also presented.
The detailed description of the current sensor could permit more standardized study of MRI gradient current induction in pacemaker systems. Results show the potential of gradient currents to affect the pacemaker capability of triggering a heartbeat, by modifying the overall energy delivered by the stimulator.
磁共振成像（MRI）过程中产生的梯度场有可能在植入的心内膜导线上感应出电流。这种电流是否会导致不期望的心脏刺激尚不清楚。
本文详细描述了如何构建一个光耦合传感器，用于测量进入心内膜导线的梯度场感应电流。该系统基于一个微控制器，该微控制器用作模数转换器，并将从导线获取的电流信号发送到一个高速光发射二极管发射器。一根塑料光纤将MRI腔室外的光引导至光电二极管接收器，然后再到连接到笔记本电脑的采集板。
该系统的性能已根据功耗（平均8 mA）、采样频率（20.5 kHz）、测量范围（-12.8至10.3 mA）和分辨率（22.6 μA）进行了表征。还展示了在3 T MRI扫描仪内的结果。
对电流传感器的详细描述可以使起搏器系统中MRI梯度电流感应的研究更加标准化。结果表明，梯度电流有可能通过改变刺激器传递的总能量来影响起搏器触发心跳的能力。
