Development of the next generation MR Elastography actuator

本研究的目的是开发一种基于气动球体振动器的强大的紧凑型磁共振弹性成像(MRE)驱动器的新技术。这是一种紧凑的致动器，利用压缩空气通过内部球的高速旋转产生强大的离心力振动。该设备原理简单，结构简单，操作方便。振动频率和离心力可通过改变空气压力(空气流量)和更换内球自由调节。为了实现磁共振成像的兼容性，所有部件都是由非铁磁材料构建的。振动幅度(位移)由激光位移传感器进行光学测量。从位移台架试验来看，虽然振动频率有所增加，但位移量并没有减少。磁共振磁共振成像的一个基本步骤是通过致动器在组织内产生机械波，磁共振成像序列与振动的几个相位偏移同步。该系统利用四通道光纤传感器检测相位偏移，并将其作为磁共振成像的触发信号。在琼脂糖凝胶模型实验中，这种致动器被用来制作磁共振弹性图。研究表明，在磁流变液中使用球驱动器是可行的。

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.