Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, Higashiogu, Arakawa-ku, Tokyo, Japan.
Magn Reson Imaging. 2013 Jul;31(6):939-46. doi: 10.1016/j.mri.2013.02.001. Epub 2013 Apr 18.
The purpose of this study was to develop a new technique for a powerful compact MR elastography (MRE) actuator based on a pneumatic ball-vibrator. This is a compact actuator that generates powerful centrifugal force vibrations via high speed revolutions of an internal ball using compressed air. This equipment is easy to handle due to its simple principles and structure. Vibration frequency and centrifugal force are freely adjustable via air pressure changes (air flow volume), and replacement of the internal ball. In order to achieve MRI compatibility, all parts were constructed from non-ferromagnetic materials. Vibration amplitudes (displacements) were measured optically by a laser displacement sensor. From a bench test of displacement, even though the vibration frequency increased, the amount of displacement did not decrease. An essential step in MRE is the generation of mechanical waves within tissue via an actuator, and MRE sequences are synchronized to several phase offsets of vibration. In this system, the phase offset was detected by a four-channel optical-fiber sensor, and it was used as an MRI trigger signal. In an agarose gel phantom experiment, this actuator was used to make an MR elastogram. This study shows that the use of a ball actuator for MRE is feasible.
本研究旨在开发一种基于气动球振子的新型强力紧凑型磁共振弹性成像（MRE）驱动器技术。这是一种紧凑型驱动器，通过内部球的高速旋转利用压缩空气产生强大的离心力振动。由于其简单的原理和结构，该设备易于操作。通过改变气压（气流体积）和更换内部球，可以自由调节振动频率和离心力。为了实现与 MRI 的兼容性，所有部件均由非铁磁材料制成。通过激光位移传感器进行光学测量来测量振动幅度（位移）。从位移的台架测试中可以看出，尽管振动频率增加，但位移量并没有减少。MRE 的一个基本步骤是通过驱动器在组织内产生机械波，并且 MRE 序列与振动的几个相位偏移同步。在该系统中，通过四通道光纤传感器检测相位偏移，并将其用作 MRI 触发信号。在琼脂糖凝胶仿体实验中，该驱动器用于制作 MRE 图像。本研究表明，使用球驱动器进行 MRE 是可行的。
