Performance evaluation of a prototype pneumatic driver for MR elastography by MR elastography

Magnetic resonance elastography (MRE) is an MR imaging technique which can be used to visualize acoustic strain wave propagation in tissues and quantify their stiffness when they are subjected to external mechanical excitation. Generation of acoustic mechanical waves within tissue via a coupled, MR compatible mechanical driver with stable phase and amplitude is crucial in these experiments. Among the several methods to generate the mechanical waves, pneumatic driver is popular because of its low cost and good MR compatibility. However, it is not easy to evaluate the pneumatic driver´s performance when different passive drivers and tubes of various dimensions are used. This paper describes the evaluation of a prototype pneumatic driver without load using ultrasound, and compared the results under load using the phase images from MRE experiment. Our experiment showed that the frequency and amplitude of the mechanical wave used should be carefully adjusted for different applications.