Indications for MRI of breast diseases: 1. Diagnosis of breast cancer When the nature of the lesion cannot be determined by mammography or ultrasound imaging, MRI can be considered for further examination. 2.Staging of breast cancer Because of the high sensitivity of MRI to invasive breast cancer, it helps to detect multiple lesions and multicentric lesions that cannot be detected by other imaging examinations, and helps to show and evaluate the invasion of the pectoralis fascia, pectoralis major, anterior serratus and intercostal muscles by the cancer. MRI with breast enhancement is recommended before surgical planning, especially when breast preservation treatment is considered. For patients diagnosed with breast cancer who are undergoing neoadjuvant chemotherapy, MRI before, during and at the end of chemotherapy can help to evaluate the responsiveness of the lesion and to determine the extent of residual lesion after chemotherapy. 4.Patients with metastatic lymph nodes in the axilla but unknown primary lesion For patients with metastatic lymph nodes in the axilla, but the primary lesion is not clearly identified by clinical examination, radiography and ultrasound, MRI can help to detect hidden cancer foci in the breast and determine the location and extent for further treatment. Negative MRI results can help to exclude the primary foci in the breast and avoid unnecessary total mastectomy. 5.Monitoring of recurrence after breast-conserving surgery For patients whose breast-conserving surgery (including histoplasty) cannot be determined by clinical examination, mammography or ultrasonography whether there is recurrence, MRI helps to identify tumor recurrence and postoperative scarring. 6.Follow-up after mammaplasty For those who have difficulty in mammographic evaluation after breast implantation, MRI can help in the diagnosis of breast cancer and evaluation of the integrity of the implanted prosthesis. 7.Screening for high-risk groups Recent clinical trials have shown that MRI can detect clinical, mammography and ultrasound negative breast cancer in high-risk groups prone to breast cancer. 8.NMR-guided puncture biopsy Contraindications to MRI for breast disease 1.Women during pregnancy. Pacemakers, surgical metal clips and other ferromagnetic materials in the body, as well as other people who are not allowed to approach strong magnetic fields. 3.Patients suffering from claustrophobia. 4.Patients with a history of allergy to any gadolinium chelate. Optimal time of examination: Since the enhancement of normal breast tissue is most significant during the secretory phase of the menstrual cycle, the MRI examination of the breast should be scheduled for 7-14 days of the menstrual cycle.