When is this exam indicated?
- Screening of women with genetic risk or high family history risk for breast cancer.
Breast MRI has proven to be the reference examination in case of genetic mutation, BRCA1/2, and in cases of high risk due to the family or personal history of the woman. The monitoring of such women includes breast MRI on a yearly basis, alternating at 6 months with mammography over 35/40 years or ultrasound for younger women.
- In case of metastases of unknown origin, a search for primary tumor at probable breast site, with clinical examination of the breast, mammography and ultrasound are negative.
In case of metastases of mammary origin, in the absence of obvious breast cancer on examination, mammography and ultrasound, MRI can identify 50% of breast tumors not visible otherwise.
- Local staging of malignant tumors already diagnosed with traditional techniques.
Numerous studies have shown that this examination is better in defining the size of the tumor; it can identify, better than mammography and ultrasound, the presence of other tumors existing alongside. When the tumor is large, MRI is the only examination that allows to define it exactly, allowing to assess whether there is infiltration of the muscles of the chest wall. The use of this examination, however, does not always bring a real benefit: for this reason this indication should always be agreed with the surgeon and the oncologist.
- Monitoring the response of the breast tumor to neoadjuvant chemotherapy.
In particular tumors chemotherapy is performed prior to surgery. In these cases the MRI has proved to be particularly accurate in defining the response to therapy, therefore, sometimes in agreement with the oncologist, it is used to monitor the treatment response.
- Examination of breasts with implants.
In case of suspicion of complications to the prosthetic implant (thickening fibrotic capsule, hematoma) or in case of rupture of the prosthesis itself, the MRI has proved to be particularly useful.
- Discrepancy between mammography images, ultrasound images and clinical examination (Problem solving).
MRI might be recommended in this case. When at an examination there is suspicion of cancer, not confirmed by other tests, the use of MRI may be justified to resolve the doubt. It is important to emphasize that in any case MRI does not replace needle core aspiration or needle core biopsy.
How is it performed?
The examination lasts on average about ten minutes, but can last up to half an hour in case of breast implant evaluation. For the success of the examination it is essential that the woman remains absolutely still. In fact, numerous images are necessary that, once acquired, must be overlapped with each other for computer processing. The examination does not involve any pain. MRI always involves the simultaneous study of both breasts, in their entire volume.
Since it complements the traditional examinations, it is essential that the woman goes for the examination with all the breast documentation in her possession, in particular mammography and ultrasound.
Paramagnetic contrast agent, a medicine that is injected into a vein in the arm during the exam, is required to evaluate the breast. Without the use of contrast medium, lesions cannot be distinguished from normal breast tissue. This contrast medium is very different from that used for CT scans and usually does not cause any problems.
The examination, if not urgent, should be performed between the 5th and 15th day of menstruation or after suspension of hormone replacement therapy. A 3-hour fastening is required before the procedure. In the days preceding the examination, within 1 month, a blood sample should be taken to assess creatinine levels.
This test cannot be performed in case of:
- presence of a pacemaker;
- presence of ferrous metal prosthesis;