Development of the next generation MR Elastography actuator

本研究的目的是开发一种基于气动球振动器的强大紧凑型磁流变弹性成像（MRE）致动器的新技术。这是一种紧凑的执行器，通过使用压缩空气的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空气压力的变化（空气流量）和更换内部球自由调节。为了实现MRI兼容性，所有部件都由非铁磁性材料构成。振动幅值（位移）由激光位移传感器光学测量。从台架位移试验来看，即使振动频率增加，位移量也没有减少。MRE的一个重要步骤是通过驱动器在组织内产生机械波，MRE序列与振动的几个相位偏移同步。在该系统中，相位偏移由一个四通道光纤传感器检测，并作为MRI触发信号。在琼脂糖凝胶幻影实验中，使用该驱动器制作MR弹性图。研究结果表明，采用球型作动器进行MRE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.