The purpose of this study is to further use DCE-MRI and ivim-dwi to predict the chemotherapy sensitivity of liver metastasis of breast cancer at an early stage, and to predict the treatment response of tumor at an early stage by using the changes of their functional parameters, and to compare the efficacy and advantages of IVIM functional parameters and DCE-MRI parameters in predicting the efficacy.To explore the efficacy of "perfusion" and "diffusion" parameters of magnetic resonance imaging as "biomarkers" for early prediction of chemotherapy response and prognosis of breast cancer patients with liver metastasis. And to provide guidance for optimizing the clinical treatment scheme of breast cancer patients with liver metastasis.

At the same time, this study will use the method of artificial intelligence to deeply mine the images, and further find out the indicators for early prediction of the therapeutic effect of liver metastasis of breast cancer.

The first MR examination was arranged within 7 days before treatment (baseline). The MRI scanning sequence included conventional T1, T2 weighted imaging, T1+dynamic contrast enhanced imaging, and IVIM-DWI imaging.The second and third MR examinations were arranged within 7 days after the first chemotherapy and the second chemotherapy. The examination steps and parameters were the same as those of the first examination.

Inclusion Criteria:

1. The primary lesion was pathologically confirmed to be breast cancer, and the patients diagnosed by two imaging methods or pathologically confirmed to be liver metastasis of breast cancer had at least one liver metastasis with the longest diameter ≥ 10mm;
2. No second primary malignant tumor;
3. ECOG score, 0-2 ;
4. The organ function is normal and can tolerate chemotherapy and other anti-tumor treatments;
5. The patient plans to receive systemic chemotherapy or systemic anti-tumor treatment, and the whole process of cooperative treatment. The patient has good compliance with the planned treatment and follow-up, can understand the research process of this study and sign a written informed consent；
6. Contraception during the study period and within 6 months after treatment, non lactation period.

Exclusion Criteria:

1. For patients contraindicated to MR examination, such as built-in metal instruments and allergy to contrast agents;
2. The patient had diffuse liver metastasis or the number of liver metastatic tumors was more than 5;
3. Patients who cannot complete 2 cycles of chemotherapy or systemic anti-tumor treatment;
4. Unable to cooperate with follow-up；
5. Patients who are not suitable for the study according to the investigator.

Patients with liver metastasis from breast cancer requiring at least 2 cycles of systemic chemotherapy

Decide whether to share individual participant data after clinical research reaches a certain stage