Department of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Biomedical and Health Science, Konkuk University, 322 Danwol-dong, Chungju, Chungbuk 380-701, Korea.
Behav Res Methods. 2011 Sep;43(3):897-901. doi: 10.3758/s13428-011-0082-z.
The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and power supply were located in a shielded case, which was made of copper and aluminum. The motion signal was modulated to an optic signal using pulse width modulation, and the modulated optic signal was transmitted outside the MR shield room using a high-intensity light-emitting diode and an optic cable. The motion signal was recorded on a PC by demodulating the transmitted optic signal into an electric signal. Various kinematic variables, such as angle, acceleration, velocity, and jerk, can be measured or calculated by using the motion measurement system developed here. This system also enables motion tracking by extracting the position information from the motion signals. It was verified that MR images and motion signals could reliably be measured simultaneously.
本研究旨在开发一种具有磁共振（MR）兼容性和安全性的简单运动测量系统。这里提出的运动测量系统可以测量 5 自由度运动信号，而不会使 MR 图像恶化，并且对强且均匀的主磁场、时变的时间梯度磁场（随时间快速变化）、收发射频（RF）线圈以及在 MR 数据采集期间的 RF 脉冲没有影响。三轴加速度计和两轴陀螺仪用于测量 5 自由度运动信号，并用魔术贴将传感器模块固定在手指或手腕上。为了将 MR 成像系统和运动测量系统之间的干扰最小化，在 MR 屏蔽室内使用非磁性材料制造所有电路组件。为了消除 RF 脉冲的影响，放大器、调制电路和电源位于屏蔽盒中，该屏蔽盒由铜和铝制成。运动信号通过脉宽调制调制为光信号，并使用高强度发光二极管和光纤将调制后的光信号传输到 MR 屏蔽室外。通过将传输的光信号解调为电信号，运动信号可以在 PC 上记录。通过使用这里开发的运动测量系统，可以测量或计算各种运动变量，如角度、加速度、速度和冲击。该系统还可以通过从运动信号中提取位置信息来实现运动跟踪。验证了可以可靠地同时测量 MR 图像和运动信号。
