Purpose: To model and predict the dynamics of conductive nonmagnetic objects moved within the MRI room under the influence of Lenz effect. High frequency motions, like vibrations induced by gradient eddy currents are not taken into account. Methods: The dynamics are described by an ordinary differential equation and the Lenz effect approximated under the assumption of negligible skin effect. This allows to separate the Lenz effect dependency on the object position and velocity, leading to a simple numerical procedure for objects of any shape. Results: The proposed model and numerical procedure were validated with experimental data recording the rotation of an aluminium plate falling inside a 1.5 T MRI scanner. The model was also applied for studying the translation of an aluminium plate pushed with constant force towards the MRI bore through the fringe field. Conclusion: The collected results showed that it is possible to obtain accurate predictions of motion in the presence of Lenz effect by neglecting the skin effect while determining the motional eddy currents induced in the metallic object.

翻译：目的：对导电非磁性物体在MRI室内受楞次效应影响下的运动动力学进行建模与预测。本文不考虑梯度涡流引起的高频运动（如振动）。方法：通过常微分方程描述动力学过程，并在忽略趋肤效应的假设下近似计算楞次效应。该方法可将楞次效应分解为对物体位置和速度的依赖关系，从而为任意形状物体提供简单的数值计算流程。结果：所提出的模型与数值方法通过记录铝板在1.5 T MRI扫描仪内下落旋转过程的实验数据进行了验证。该模型还应用于研究铝板在恒定推力作用下穿过边缘场向MRI孔道平移的运动。结论：实验结果表明，在确定金属物体中感生运动涡流时，通过忽略趋肤效应可获得楞次效应作用下运动的精确预测。