A Fully Electronically Steerable Therapeutic Ultrasound Phased Array With MR-Guidance

Recently, MRI-guided focused ultrasound (FUS) has shown great promise in treating various conditions non-invasively. Objective: The focus of this article is to introduce an MRI-guided FUS device, which can provide full electronic steering range without mechanical movement and with low near-field heating. A pilot study was conducted in order to investigate the feasibility, and safety of the device in a large animal model and a pilot clinical trial. Methods: A flat, fully steerable FUS phased array with 4096 elements was designed and manufactured to be compatible with an MR scanner. Pre-clinical experiments were carried out for testing the accuracy of the focus at different steering angles as well as evaluating the ablation efficiency using MR thermometry. Eleven patients with uterine fibroids were treated in the pilot clinical trial. Results: Pre-clinical results showed successful ablation at various steering angles with reasonable targeting accuracy and no off-target heating. During the pilot clinical study, effective fibroid ablation was achieved with significant symptom reduction observed over time. In general, the treatment results showed the system to be effective in ablating deep tissue volumes. The device was successful at efficiently ablating large volumes with minimal near-field heating and eliminating the need for mechanical translation. Conclusions: Being capable of providing high acoustic power, full electronic steering range in 3D for large volume ablations, this device can provide a safe and efficient treatment option as an outpatient procedure for uterine fibroids and other pelvic and abdominal tumors.