1. Screening of high risk patients
In patients who have tested positive for mutations of the BRCA 1 and 2 genes, MRI has been shown to detect cancers before mammography, ultrasound or clinical examination could detect the malignancy. The greater incidence of high grade invasive malignancies in this high risk group does provide the rationale for using MRI as a screening modality in this small group of women.  Women who do not have identified mutations but who have family histories do suggest mutations according to the Hereditary Cancer Program should also be considered appropriate for MRI screening.  Currently this is done at annual intervals with mammography done annually 6 months apart from the MRI.

2.  Evaluation of occult breast cancer
In patients with a hidden primary cancer presenting with auxiliary lymphadenopathy or Paget's disease, MRI has been shown to identify the primary cancer in many patients, thus allowing for conservative surgery rather than mastectomy.

3. Evaluation of local extent of breast cancer
MRI can be useful in pre-operative assessment of local disease extent when this is unclear either by physical examination, mammography or ultrasound. 

4. Positive margins – post segmental resection
MRI can be useful in determining the extent of residual disease when margins are positive and the mammogram is not helpful.

5. Post surgical scar vs. recurrent tumor
In cases where mammography and ultrasound are inconclusive in patient suspected of recurrent disease, MRI can be helpful.  Breast tissue can show enhancement for up to 18 months following radiation therapy, however.  In many of these situations a biopsy will be necessary to rule out disease and may be a preferable diagnostic test.

6. Problem mammogram
MRI can be useful in a small number of patients when there is an equivocal mammographic finding, i.e. a possible architectural distortion, or mass seen only in one view, in whom there is no ultrasound or clinical correlate.  Many of these patients have heterogeneously dense breasts. 

7. Response to chemotherapy
MRI has been used to monitor treatment response to nedoadjuvant chemotherapy in patients with locally advanced cancer. 

8. Evaluation of implants
MRI has been shown to be more reliable than CT, ultrasound or mammography for assessment of rupture/integrity/complications of breast implants. The FDA guidelines for silicone gel implants require women to have breast MRI to evaluate for leakage in 3 years and then every 2 years thereafter.