Real-time monitoring of transcranial focused ultrasound in vivo

Transcranial focused ultrasound (tFUS) is being investigated in a variety of medical applications. Both thermal and mechanical bioeffects of tFUS are of interest, but localization of the tFUS therapeutic beam remains a major concern in the presence of beam distortion through the skull. We have developed a system for monitoring and delivery of tFUS using dual-mode ultrasound array (DMUA) transducers. The system is capable of delivering therapeutic tFUS in pulsed mode with imaging pulses interleaved at frame rates up to 500 fps utilizing the same array elements. In this way, the DMUA provides inherent registration between the imaging and therapy system thus providing feedback from the target region as well as tissue structures in the path of the beam. The beamformed DMUA echo data was used to image the thermal and mechanical tissue response to the tFUS beam with high spatial specificity. In vivo data from small-animal experiments have shown a temperature sensitivity of 0.2°C with high spatial specificity. S...