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Breast MRI

Frequently Asked Questions Regarding Breast MRI

What is breast MRI?

Breast MRI is a highly sensitive noninvasive test which examines the inside of the breast through hundreds of images. There is no compression or flattening of the breast during this exam and there is no radiation exposure.

Who is a candidate for breast MRI?

Most patients getting a breast MRI fall into three categories:

a. Patients with newly diagnosed breast cancer.

In patients with newly diagnosed breast cancer, breast MRI can be quite helpful in determining the exact tumor size and extent which can allow for much more accurate surgical planning. Sometimes there is an unsuspected second cancer or the tumor proves to be larger than originally thought in as many as 10% of the cases, which can drastically change the surgical approach and outcome.

b. Patients who have a diagnostic problem which cannot be answered with mammography and breast ultrasound.

An example of a diagnostic problem includes a breast lump that is suspicious on physical exam, but not detected by conventional imaging with mammography or ultrasound. Another common diagnostic problem is an ultrasound or mammographic finding for which the radiologist recommends further evaluation.

c. Patients who are suspected to have a breast implant rupture.

MRI is the most accurate test to determine the integrity of a breast implant.

How is the procedure done?

The patient lies face down on a special breast MRI table which allows her breasts to hang through an opening which will allow the MRI to provide very detailed images of each breast. A simple IV line is established beforehand to allow injection of a type of contrast which will help the radiologist determine whether there is an area in the breast which is suspicious for cancer. The patient must be able to lie still, and the exam takes approximately 30 minutes.

Why is an IV necessary?

The IV is needed to give a special type of MRI contrast called gadolinium. Breast cancers typically have a rich blood supply, so tumors “light up” on MRI. It is this contrast that makes MRI more sensitive in cancer detection than mammography. Allergies to this type of dye (which is different than “x-ray dye”) are extremely rare.

If the breast MRI is normal, am I cancer free?

If the exam is normal, then the chances of the patient having breast cancer are extremely low.

Is breast MRI a better test than mammography?

The two tests are both great exams, each with their own strengths. Most commonly, breast MRI is performed to answer a specific question raised from the patient’s mammogram. Breast MRI is a more sensitive test in detecting breast cancer than mammography. There are some cancers that can be seen with MRI that cannot be seen with mammography. This is especially true in patients who have dense breast tissue. Regardless of breast density, if a breast cancer is present, breast MRI can detect it greater than 95% of the time, while mammography can detect cancer approximately 80-90% of the time. If the patient has dense breast tissue, the rate of detection of cancer can go down to as low as 50% by mammogram alone. For this reason, breast MRI can be quite helpful in this sub-group of patients who have dense breast tissue on their mammograms and a change in their mammogram, a palpable lump or a biopsy-proven cancer.

If MRI is a more sensitive test than mammography, can I just have this test instead of a mammogram each year?

No. All breast MRI’s should be read in conjunction with the patient’s mammogram. Both mammography and MRI have different strengths. For example, mammography is better at detecting very tiny calcifications, which can be an early sign of breast cancer.