The lifetime risk of a woman developing breast cancer is 10-12%. Nearly all women are affected by this cancer,either personally or through a loved one. The good news: breast cancer has become a treatable, and often curable, disease due to early and more thorough detection of breast cancer and better treatment strategies. Breast Magnetic Resonance Imaging (MRI) offers a unique way of detecting breast cancer and sometimes finds cancers that mammography (x-rays) and ultrasound (sound waves) can miss. MRI uses magnetic fields and radio frequency pulses to create a picture of the breast based on the innate properties of breast tissue. It also utilizes a contrast “dye” that shows the blood flow within the breast; in general, breast cancers and precancers collect more of the dye than healthy breast tissue, allowing us to detect them. Thus, MRI, unlike mammography and ultrasound, allows breast imagers to see not only the morphology (anatomy) of the breast but also the physiology (real time function) of the breast and tumors.
When should breast MRI be performed?
1. Presurgical planning – Women with a new diagnosis of breast cancer have a 4% chance of having another simultaneous cancer in the opposite breast that is invisible on mammogram. Additionally, women with a new cancer can sometimes have a larger tumor or more tumors in the same breast that were not originally detected. Breast MRI can also show diseased lymph nodes in places not imaged by mammography or ultrasound. By having an MRI before surgery, additional disease can often be treated with a single surgery.
2. High risk screening – Women with a 20-25% or greater life time risk of developing breast cancer are considered ” high risk.” This includes women with a strong family history of cancer, those with gene mutations (BRCA1/2 are the most well known), those with a history of chest radiation between ages of 10- 30 (often for child hood lymphoma ), and some women with a history of biopsies showing atypical cells. Because MRI is very sensitive for identifying breast cancer, high risk women can benefit from regular breast MRI screening.
3. Problem solving – Women with suspected breast implant rupture, lumps, or pain not explained by mammography or ultrasound can benefit from breast MRI.
What can a patient expect?
A dedicated breast MRI machine will have a table with holes in it; a woman lies face down on the table and her breast hang down into the holes. The table then moves her into a doughnut shaped machine (the magnet}. She will hear a series of clicks and humming; she will have earplugs and a communication buzzer in her hand in case she want to talk to the technologist (who will sit in an adjacent room with a window). After a few series of images, contrast dye will be run into an IV in her arm – this might feel cool in the arm and often makes her feel a little flushed (which is normal). The entire scan usually takes about 45 minutes.
What are the risks of breast MRI? Who should not have an MRI?
Very rarely, a woman can have an adverse reaction to the dye administered. Women that are claustrophobic can be uncomfortable in an MRI scanner; a nxiolytic medication can help. Women with some pacemakers, metal in their eyes, and some ear surgeries should not have an MRI. Women with kidney failure or pregnant should not be given contrast dye.
Who should perform and read my MRI?
An experienced radiologist should interpret the MRI and perform a biopsy, if needed. The MRI machine and center should be accredited by the American College of Radiology (ACR) or lntersocietal Commission for the Accreditation of Magnetic Resonance Laboratories (ICAMRL), dedicated to breast imaging, and able to per form MRI-guided biopsies, in case a biopsy is warranted.
By Helena Summers, MD, Staff Radiologist, Triad Radiology Associates