title: A simple 5-DoF MR-compatible motion signal measurement system.
abstract: 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.
authors.affiliation: 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.
authors.forename: Soon-Cheol
authors.initials: SC
authors.lastname: Chung
authors.forename: Hyung-Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Jae-Woong
authors.initials: JW
authors.lastname: Yang
authors.forename: Su-Jeong
authors.initials: SJ
authors.lastname: Lee
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Choi
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Kim
authors.forename: Hong-Won
authors.initials: HW
authors.lastname: Yeon
authors.forename: Jang-Yeon
authors.initials: JY
authors.lastname: Park
authors.forename: Jeong-Han
authors.initials: JH
authors.lastname: Yi
authors.forename: Gye-Rae
authors.initials: GR
authors.lastname: Tack
mesh_terms: D003625:Data Collection / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009038:Motion; D009068:Movement