Dynamic contrast-enhanced MRI in breast cancer treated with neoadjuvant chemotherapy: correlation with pathological response

Objective: To investigate the relationship of pathological response of breast cancer after neoadjuvant chemotherapy with the imaging findings in dynamic contrast-enhanced MRI. Methods: Forty- five patients with pathologically confirmed breast carcinoma who finished courses of neoadjuvant chemotherapy had breast MRI prior to operation. Dynamic contrast-enhanced MRI scans were performed on a 1.5 T scanner using 3D SPGR sequence before and repeated 6 times after administration of Gd-DTPA. Pathological response was assessed by a pathologist according to Miller and Payne five points classification blinded to breast MRI results. Grade 5 was defined as pCR (pathological complete response). Grade 4 and 5 were defined as major histopathological response (MHR). The type of time signal intensity curve (TIC) (three types), pattern of residual enhancement of each breast cancer were recorded and correlated with pathological findings. Fisher exact test was used for statistical analysis. Results: Grade 5 responses were achieved in seven patients; grade 4 in sixteen patients; grade 3 in sixteen patients and grade 1-2 in six patients. 70.0% (14/20) of type I time signal intensity curve correlated with MHR, while all 6 type III curves showed non-MHR response. The type of time signal intensity curve and pathological response grades had statistically significant correlation (P=0.001). 18 of the 23 cases with MHR exhibited residual enhancement,while the remaining 5 cases showed no enhancement. Of the 18 MHR cases with residual enhancement, 11 showed non-mass-like enhancement and 7 showed mass-like enhancement. The mass (non-mass) morphological pattern in dynamic contrast enhanced-MRI had statistically significant differences in pathological response (P=0.012). Conclusions Pathological response of breast carcinoma after neoadjuvant chemotherapy could be characterized using dynamic contrast-enhanced MRI by identifying patterns of residual contrast enhancement and kinetic curve. Favorable pathological responses correlated with Type I TIC, non-enhancement, and non-mass-like residual enhancement. (authors)