Feasibility of using ultrasound phased arrays for MRI monitored noninvasive surgery

The purpose of this paper was to evaluate the in vivo feasibility of using phased arrays for MRI guided ultrasound surgery. Two different array concepts were investigated: a spherically curved concentric ring array to move the focus along the central axis and a spherically curved 16 square element array to make the focus larger. Rabbit thigh muscles were exposed in vivo in a 1.5 T MRI scanner to evaluate the array performance. The results showed that both of the arrays performed as expected, and the focus could be moved and enlarged. In addition, adequate power could be delivered from the arrays to necrose in vivo muscle tissue in 10 s. This study was the first implementation of phased arrays for MRI guided ultrasound surgery. The results demonstrate that phased arrays have significant potential for noninvasive tissue coagulation.