The ablation of liver tumors by a non-real-time controlled, ultrasoundguided, focused ultrasound has been reported recently.The integration of focused ultrasound and magnetic resonance imaging has resulted in a new method of non-invasive surgery.By using this integrated delivery system, the surgeon can correctly localize tumors, optimally deliver acoustic energy, monitor energy deposition in real-time, and accurately control the deposited thermal dose within the entire volume of the tumor.It has been claimed that this novel technology represents a potential revolution not only in liver surgery but also in many other surgical fields.However, to allow safe and effective treatment of the liver with MRgFUS, one has to overcome the problem of respiratory movement of the liver during energy delivery.Otherwise, energy is not delivered to a focused region, and the MR system is unable to provide quality thermal imaging.