MR Imaging-guided Focused Ultrasound Surgery of Breast Cancer: Correlation of Dynamic Contrast-enhanced MRI with Histopathologic Findings

Purpose. To assess the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters to monitor residual tumor following non-invasive MRI-guided focused ultrasound surgery (MRIgFUS) of breast tumors. Methods. DCE-MRI data were acquired before and after the MRIgFUS treatment of small breast tumors (d<3.5 cm) for 17 patients. The lesion was surgically resected and the presence of residual tumor was determined by histopathological analysis. The percentage of residual tumor was correlated with three DCE-MRI parameters measured at the maximally enhancing site of each tumor: increase in signal intensity (ISI), maximum difference function (MDF) and positive enhancement integral (PEI). Results. A good correlation was found between the ISI (r= 0.897), MDF (r= 0.789) and PEI (r= 0.859) parameters and the percentage of residual viable tumor determined by histopathology. A receiver operator characteristic curve analysis yielded a cutoff value for ISI at 20% with a sensitivity of 77% and a specificity of 100%. Conclusion. These results suggest that parameters from DCE-MRI data could provide a reliable non-invasive method for assessing residual tumor following MRIgFUS treatment of breast tumors.