Preliminary clinical experiences of a motorized manipulator for magnetic resonance image–guided microwave coagulation therapy of liver tumors

BackgroundIn magnetic resonance (MR) image–guided microwave thermocoagulation of liver tumors, the choice of the optimal puncture route is an important and time-consuming process. To assist this process, we have developed a motorized MR-compatible manipulator.MethodsThe manipulator consists of a passive end effecter with 2 degrees-of-freedom (DOF) rotation and active base stages with 3 ultrasonic motors. It automatically chases the preset target point with synergetic remote-center-of-motion (RCM) control. A mechanical torque limiter and an electrical shutdown switch were added for patient safety.ResultsThe manipulator was used for this procedure in 15 cases and successfully utilized to treat liver tumors in various locations. Thoracoscopic assistance was combined with the manipulator in 6 cases. No complications were experienced.ConclusionsThe manipulator was found to be very effective for assisting MR-guided microwave coagulation of liver tumors.