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What Is MRI-Assisted Breast Biopsy?

A breast lump or abnormality in the breast is often detected by physical examination, mammography or other imaging studies. However, it is not always possible to tell from these imaging tests whether a growth is benign or cancerous.

To determine this, a breast biopsy is performed to remove some cells—surgically or through a less invasive procedure involving a hollow needle—from a suspicious area in the breast and examine them under a microscope. Image-guided needle biopsy is not designed to remove the entire abnormality, just a small portion for testing.

An image-guided biopsy is performed when the abnormal area in the breast is too small to be felt, making it difficult to locate by hand. In an MRI-assisted breast biopsy, a high-powered magnet is used to help guide the radiologist’s instruments to the site of the abnormal growth.

What Are Some Common Uses of the Procedure?

An MRI-assisted breast biopsy is performed when other imaging shows a breast abnormality such as:

  • A suspicious solid mass
  • A distortion in the structure of the breast tissue
  • An area of abnormal tissue change
  • A palpable mass not seen on mammogram or ultrasound

MRI-assisted breast biopsy is also performed when the patient or physician strongly prefers a non-surgical method of assessing a breast abnormality.

How Should I Prepare?

You may be asked to:

  • Remove some or all of your clothes and wear a gown during the exam.
  • Remove jewelry, dentures, eyeglasses and any metal objects or clothing that might interfere with the magnet.
  • Inform the physician if there is any possibility that you are pregnant.
  • Not wear deodorant, powder, lotion or perfume under your arms or on your breasts on the day of the exam.
  • Report to your doctor all medications that you are taking, including herbal supplements, and if you have any allergies, especially to anesthesia. Your physician will advise you to stop taking aspirin or blood thinners three days before your procedure.
  • Inform your doctor about recent illnesses or other medical conditions.

You may want to have a relative or friend accompany you and drive you home afterward. This is recommended if you will have to be sedated.

What Can I Expect?

Prior to the biopsy, the nurse will meet with you to complete an assessment, explain the procedure and provide paperwork as needed. A nurse or technologist will start an IV in your hand, wrist or forearm. The radiologist will then meet with you to answer any questions you might have and have you sign consent forms for the procedure.

This procedure is performed using MRI guidance with you lying on your stomach with your head slightly elevated on a special table. The technologist will help you get into a position that is the most comfortable for you. The table has openings to accommodate your breasts. Your breasts will be positioned between a plate and a grid with light compression. You may use earplugs or headphones and listen to music during the scan to drown out the loud sound from the magnet.

After the breast is scanned and the area of concern located, the radiologist will then clean the area with an antiseptic and inject local anesthetic into your breast. The radiologist will make a small cut in the skin, insert the biopsy needle and take small samples of the tissue from the area of concern. The radiologist will then place a small clip (tissue marker) in the breast to mark the place where the tissue was removed. The clip is safe and cannot be felt in the breast. It will not move. It does not affect MRI and will not set off alarms at the airport.

After the clip is placed, the nurse will compress the breast for approximately 10 minutes to stop any bleeding in the breast. The nurse will then place small steristrips (like tape) over the incision. No stitches are needed. A light compression post-procedure mammogram will be taken to ensure the clip location and visualization of the biopsy site. The samples are then sent to the lab to be examined.

The nurse will review the discharge instructions with you before you leave. A copy of the discharge instructions will be provided for you to take home and refer to. Download our Breast Biopsy Pre- and Post-Procedure Instructions to learn more about what you can expect with this procedure. 

What Are the Benefits and Risks?


  • The procedure is less invasive than surgical biopsy, leaves little or no scarring and can be performed in less than an hour.
  • It’s an excellent way to evaluate masses that are not visible on ultrasound.
  • It’s a simple procedure that may be performed in an outpatient imaging center.
  • Generally, the procedure is not painful and the results are as accurate as when a tissue sample is removed surgically.
  • No breast defect remains, and unlike with surgery, MRI-assisted breast biopsy does not distort the breast tissue and make it difficult to read future mammograms.
  • Recovery time is brief, and patients can soon resume their usual activities.


  • Because the vacuum-assisted device removes slightly larger pieces of tissue than other types of needles, there is a risk of bleeding and forming a hematoma, or a collection of blood at the biopsy site. The risk, however, appears to be less than 1% of patients.
  • An occasional patient has significant discomfort, which can be readily controlled by non-prescription pain medication.
  • Any procedure where the skin is penetrated carries a risk of infection.

Who Interprets the Results and How Do I Get Them?

A pathologist examines the removed specimen and makes a final diagnosis. Our board-certified radiologists will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

If you would like to schedule an appointment, please call 678-312-3444.