OBJECTIVETo assess the value of dynamic contrast-enhanced MRI (DMRI) in predicting early response to neoadjuvant chemotherapy (NAC) in patients with locally advanced breast cancer (LABC) and to assess the accuracy of MRI in evaluation of residual disease after NAC.

METHODSForty-three women with LABC (44 lesions, all were invasive ductal carcinoma) underwent DMRI before, after the first and final cycles of NAC. For each patient, the tumor volume, early enhancement ratio (E1), maximum enhancement ratio (Emax), and maximum enhancement time (Tmax), dynamic signal intensity-time curve were obtained during treatment. The residual tumor volumes obtained by DMRI were compared with pathological findings to assess the accuracy of DMRI.

RESULTSAfter the first cycle of NAC, the mean volume of responders decreased insignificantly (P = 0.055), but after NAC, mean volume of residual tumor decreased significantly (P = 0.000). Morphological changes: 29 cases showed a concentric shrinkage pattern while 7 cases showed a dendritic shrinkage pattern. Significant differences were found in E1, Emax and Tmax between responders and non-responders (P < 0.05). After the first cycle of NAC, E1, Emax and Tmax of responders changed significantly (P < 0.001), while there was no significant change in non-responders (P > 0.05). After NAC, the dynamic signal intensity-time types were changed in responders, and tended to be significantly flattening, while no significant change was found in non-responders. The residual tumor volume correlation coefficient between MRI and pathology measurements was very high (r = 0.866, P < 0.01).

CONCLUSIONDMRI is useful to evaluate the early response to NAC in LABC. The presence and volume of residual tumor in LABC patients treated with NAC can be accurately evaluated by DMRI.