MRI-Guided Breast Biopsy

This information will prepare you to have a magnetic resonance imaging (MRI) core biopsy of your breast.

An MRI uses strong magnetic fields to produce pictures of the inside of your body. These pictures will be used to find the exact area for your biopsy. The sample of your tissue removed during your biopsy will be examined to help your doctor make a diagnosis.

If you have any of the devices listed below, call 646-227-2323. It may not be safe for you to have an MRI.

  • Pacemaker
  • Automatic implantable cardioverter-defibrillator (AICD)
  • Breast tissue expander
  • Aneurysm clip

If an MRI is not safe for you, your doctor will order a different test. If you have any other questions about your MRI, call your doctor’s office.

About Your Appointment

You will receive a phone call the day before your procedure to confirm your appointment time.  If you do not receive a call by noon, please call the site where you are scheduled to have your procedure. Those telephone numbers are listed below.

  • MSK Basking Ridge: 136 Mountain View Boulevard, Basking Ridge, NJ 908-542-3200
  • MSK Commack:  650 Commack Road, Commack, NY 631-623-4300
  • Evelyn H. Lauder Breast Center: 300 East 66th Street (at Second Avenue); elevator to 6th floor 646-888-5300
  • Memorial Hospital: 1275 York Avenue (between East 67th and East 68th Streets), “M” elevator to 2nd floor to CIGI 212-639-8200
  • MSK Westchester: 500 Westchester Avenue, West Harrison, NY 914-367-7036
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Before Your Procedure

  • If you have a medical implant or device, ask the doctor who put it in for the exact name and manufacturer. If you don’t have this information before your MRI, you may not be able to have it that day.
  • If it is hard for you to lie on your stomach for about 1 hour, or if you’re afraid of being in a narrow or small space, talk with your doctor ahead of time. He or she may prescribe medication to help you be more comfortable.


  • If you take medication to thin your blood, (called anticoagulants or blood thinners), such as to treat blood clots or to prevent a heart attack or stroke, ask the doctor who prescribed your medication what to do. Some examples are aspirin, warfarin (Coumadin®), dalteparin  (Fragmin®), heparin, tinzaparin (Innohep®), enoxaparin (Lovenox®), clopidogrel (Plavix®), cilostazol (Pletal®), prasugrel (Effient®), and ticlopidine (Ticlid®). The doctor who referred you for your procedure or your cardiologist should be involved in any decision to stop taking your anticoagulant. When you talk with him or her about your procedure, share the information below. If your doctor has any questions, he or she should call the location where you are having your procedure and ask for the Breast Imaging doctor. Those telephone numbers are listed above.


    • You should not take warfarin (Coumadin) 5 days before your biopsy.  A blood test called an INR may be performed if your previous value was greater than 4.  You may take subcutaneous heparin (shots) the night before to your procedure.  Ideally, aspirin, clopidogrel (Plavix) and nonsteroidal anti-inflammatory drugs (NSAIDs) should not be taken for 5 days before your biopsy procedure.  Your doctor will tell you when it’s safe to start taking anticoagulants again. It’s usually the same day after your procedure as long as there is no significant bleeding.
    • In certain circumstances, anticoagulants cannot be stopped safely. If this is the case because of medical conditions, or if your risk of developing a blood clot is too high, your radiologist will determine whether he or she can perform the biopsy.
  • If you take vitamin E, stop taking it 5 days before your procedure. Please review the information in Common Medications Containing Aspirin and Other Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) for examples of what not to take and what to take instead.


  • If your doctor told you that you would receive anesthesia (medication to make you sleepy) while you have your procedure, you must follow these additional instructions:
    • Arrange for a responsible adult to take you home
    • Leave all valuables, such as credit cards and jewelry, at home.
    • If you wear contact lenses, wear your glasses instead.

Instructions for eating and drinking before your procedure

12 ounces of water

  • Do not eat anything after midnight the night before your procedure. This includes hard candy and gum.
  • Between midnight and up until 2 hours before your scheduled arrival time, you may drink a total of 12 ounces of water (see figure).
  • Starting 2 hours before your scheduled arrival time, do not eat or drink anything. This includes water.

The Day of Your Procedure

Things to remember

  • Take only the medications your doctor told you to take the morning of your procedure. Take them with a few sips of water.
  • If you are not receiving anesthesia you may eat and drink before your MRI, but please eat lightly.
  • Refer to the printed reminder you received from your doctor’s office for the time and location of your MRI.
  • If you wear a medication patch on your skin, bring an extra one with you. We may ask you to remove the patch before your MRI. This is because metal in the patch may heat up during your MRI and cause burns. If you wear a fentanyl patch, you can leave it on during your MRI.
  • Contrast dye might be used during your MRI to make it easier to see the biopsy target. It will be given through an intravenous (IV) catheter placed in your hand or arm or through an implanted port or central line. If you have had a reaction to contrast dye in the past, call your doctor’s office. If you are going to get contrast dye, your doctor or nurse will discuss it with you first. If you are between the ages of 11 and 50, this discussion will include questions about any chance you might be pregnant.
  • You will change into a hospital gown before going into the scanning area. For safety reasons, you will place your clothing, credit and ATM cards, and any objects (such as your phone, jewelry, coins, and glasses), in a locker. This is because objects with even a small amount of metal can fly into the magnet, and the magnet can damage items such as mobile phones and credit cards.
  • You will be taken to the scanning room and helped onto the padded MRI table. You will lie facedown on your stomach with your hands above your head. Your breasts will fit into cushioned holes in the table, which contains coils that detect magnetic signals from the MRI machine. The MRI machine is a large, donut-shaped magnet. It makes a loud tapping noise while the scan is in progress. When you have been made as comfortable as possible on the MRI table, your technologist will slide it into the magnetic part of the machine. You will be able to speak with your technologist during the entire scan.
  • It is important to lie still and breathe normally during the scan. The scan itself does not hurt, but lying on the table for 45 to 60 minutes may be uncomfortable. If you think this will be a problem for you, tell your doctor before you come for the scan. The MRI images taken during the scan will help your doctor locate the biopsy target.
  • Once the biopsy target is located, a local anesthetic will be injected in the area where your doctor will be working. Your radiologist will insert a needle and remove breast tissue. This tissue will be sent to the Pathology Department to see if it contains cancer cells. A small marker may be left at the spot of your incision in order to help your doctor identify the biopsied area. You will not be able to feel this marker.
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After Your Procedure

  • When your biopsy is complete, your radiologist will place Steri-StripsTM (adhesive tape) over the incision, the scanning table will be moved away from the machine and you will be helped off the table. Your technologist or nurse will remove the IV.  After you get your belongings, an MRI technologist will escort you to the Breast Imaging Department where you will have your post-biopsy mammogram.  Your technologist will place a bandage over the Steri-Strips.
  • You will be given instructions on how to care for your biopsy incision.
  • Your radiologist will call with your biopsy results in 3 to 5 working days.
  • Your radiologist will send a report to your doctor. The results of your procedure will be used with other test results to plan your care.

Your radiologist will give you a card with his or her phone number to call if you have any questions. If you have questions after 5:00 pm, during the weekend, or on a holiday, please call 212-639-2000 and ask for the Radiology Body fellow on call.

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