A breast Magnetic Resonance Imaging (MRI) scan uses powerful magnets and radio waves to create detailed, cross-sectional pictures of the breast tissue. This technology is often used alongside mammography and ultrasound, not as a replacement. A primary use for breast MRI is screening individuals at high lifetime risk for breast cancer, such as those with a strong family history or a genetic mutation. It is also used to determine the extent of cancer after diagnosis, evaluate silicone breast implants for leaks, and clarify ambiguous findings from other imaging tests.
Preparing for the Scan
Preparation begins with strategic scheduling, especially for premenopausal women, to minimize the chance of a false-positive result. The scan should ideally be timed between day seven and day fourteen of the menstrual cycle, counting from the first day of the period. This specific window is chosen because hormonal fluctuations outside this time can cause normal breast tissue to enhance with contrast, complicating image interpretation. Patients who are postmenopausal or have irregular cycles can schedule the exam at any time.
Wear comfortable, loose clothing to the appointment, as you will change into a gown. Before entering the scanning room, all metal objects must be removed, including jewelry, hairpins, watches, and clothing with metallic fasteners. Patients must also disclose their medical history, particularly if they have a pacemaker, cochlear implant, metallic surgical clips, or shrapnel, as these items can interfere with the magnetic field or be unsafe.
A recent blood test to check kidney function is often required before the procedure. This testing is necessary because the contrast agent used during the MRI is processed and eliminated by the kidneys. Impaired kidney function poses a risk when administering the contrast agent. While you can usually eat and drink normally before the exam, follow any specific instructions regarding diet or temporary cessation of hormone replacement therapy.
The Examination Process
Once in the scanning room, you will lie face down on a padded examination table. This specialized table has cushioned openings that allow the breasts to hang freely into dedicated breast coils. The prone position separates the breast tissue from the chest wall, maximizing tissue visibility and ensuring consistent imaging.
After positioning, the table slides into the large, cylindrical MRI machine. Maintaining absolute stillness throughout the scan is necessary to prevent motion artifacts that could blur the images and require re-scanning. The MRI machine produces loud, repetitive tapping and thumping sounds as the magnetic field changes, so you will be provided with earplugs or headphones.
The total time spent inside the machine is typically between 30 and 60 minutes. During the procedure, an intravenous (IV) line is placed in your arm to administer a contrast dye, usually containing Gadolinium. This contrast agent enhances the visibility of abnormal tissue, as cancerous cells tend to absorb the dye more quickly than healthy tissue. You may feel a cool sensation or a temporary metallic taste in your mouth as the contrast is injected. A technologist monitors you from an adjacent room and communicates via an intercom system.
After the MRI: Results and Next Steps
Immediately after the images are completed, the IV line is removed, and you are free to get dressed. Since the contrast agent was injected, you will be advised to drink extra fluids over the next 24 hours to help flush the Gadolinium from your system. There are no restrictions on your activity level after the scan, and you can resume your normal routine, including driving.
The detailed images are reviewed by a specialized radiologist, who interprets the findings and generates a formal report. This report is then sent to the physician who ordered the test. Most patients receive their results from the referring physician within 24 to 48 hours, though the timeline can vary by facility.
The radiologist uses a standardized reporting system, often the Breast Imaging Reporting and Data System (BI-RADS), to categorize the findings. If an abnormality is identified, the next steps could involve a short-interval follow-up MRI, a targeted ultrasound, or a biopsy to definitively determine the nature of the finding. A finding requiring further investigation does not automatically mean cancer, as the MRI is sensitive and can detect many non-cancerous changes.