A convertible pneumatic actuator for brain and phantom elastography

0, using a toggle switch. The arbitrary function generator (Tektronix AFG3022B), triggered from the MRE pulse sequence was used to generate the desired acoustic waveforms. The system is capable to operate in a frequency range of 25 -150Hz. Three different MRE actuator configurations are available: Head actuator - thermally molded tray, which could be slit into the head coil, serves as the base for the head actuator (see Fig. 2B). Velcro® strips are used to attach the drivers to the tray. The drivers are placed in a “V” shape around the back of the head. Foam-padding installed between them provides additional support for the head. A small exchangeable towel covers the bottles and foam pad during the exam for hygienic reasons. Probe actuator – the drivers are placed in homemade brackets and attached to the coil instead of head restrainers (see Fig. 2C). The T-bar placed between the drivers is secured with Velcro® strips. The height of the actuator contact plate is adjustable, using a screw. Various contact plates can be used with the actuator according the phantom’s size and shape. Bed type actuator – when a large contact area with the source of oscillations is desirable or when the sample is enclosed in a container, the configuration can be changed to a so called bed-type actuator [4]. The holder, equipped with four rollers, is positioned into the bottom part of the head coil. The sample cart is placed on the