Objective  To investigate the correlation between the breast cancer MRI schedule of reinforcement and the shrinkage pattern of tumor after neo-adjuvant chemotherapy, and its clinical significance in the guidance of formulating operation plan.

  Methods  Dynamic contrast-enhanced MRI scan was performed before chemotherapy and before surgery after a whole-range N-Acety-L-Cysteine (NAC) treatment in 55 patients with loco-regionally advanced breast cancer who received the neo-adjuvant chemotherapy. MRI schedule of reinforcement and the shrinkage pattern of tumor after neo-adjuvant chemotherapy were obtained in the treatment, and the correlation between the two was analyzed.

  Results  Of the 55 patients, the unilateral breast mass was found in 54 and the bilateral lesion in 1. There were 56 neo-plastic foci in these patients. The mass-like enhanced image was seen in 24 of the total cases (43%), of which 23 presented with a centripetal shrinkage, 1 with an annular decline, (P < 0.01). Multifocal mass-like enhancement image was found in 13 of the total cases, (23%), of which 2 centripetal shrinkages were the singular mass, 11 remained a multifocal lesion after the tumor shrinkage (P < 0.01). The mass with peripheral non-tumor-like enhancement image was seen in 8 of the total cases (14%), of which 4 showed a centripetal shrinkage and another 4 a honeycombed multifocal decline (P>0.05). There were 11 of the total cases with non-tumor-like enhancement (20%), in which 4 assumed a centripetal shrinkage and 7 a honeycombed multifocal shrinkage (P < 0.01).

  Conclusion  The tumor shrinking pattern and its accurate radiological image evaluation are the keys to the selection of breast-conserving surgery and the control of local recurrence after treatment of NAC regimen. We can predict the shrinking pattern through the type of the lesion on baseline before NAC, which is important for the patients and surgeon to get a reasonable expectation in the subsequent treatments.