Performance analysis of a dedicated breast MR-HIFU system during ablation of breast tumors in patients

correction method was used to correct on-line for respiration-induced magnetic field fluctuations.[2] The performance of the correction method was assessed in absence of HIFU heating. The temporal standard deviation (SD) in temperature maps calculated before and after applying the correction method and the number of dynamics needed before switching to the intervention phase were used as a measure of performance. The targeting accuracy and precision of the system was assessed using MR thermometry data. For each sonication the trajectory of the center of mass of the heating pattern in the focal area over time was calculated. The standard deviation of the distribution of the distances between the center of mass in time and the mean center of mass was defined as precision. The distance between the mean center of mass and the planned treatment position was defined as accuracy.