What is MRI of the breast?
Magnetic Resonance Imaging, or MRI, uses a magnetic field, radio waves, and a computer to create three-dimensional images of the breast. MRI of the breast is one of the most sensitive imaging tools available for detecting new or recurrent breast cancer.
What is the role of breast mri?
Breast MRI is very useful in evaluating the extent of cancer within the breast in a patient with a new diagnosis of breast cancer. It helps identify additional occult breast cancers in the involved breast in 15% to 30% of patients and also helps identify occult cancer in the opposite breast in up to 3% to 7% of patients. This means that later recurrences can be reduced and your surgeon can recommend the best surgical procedure for you with the added information provided by a breast MRI. A negative breast MRI is approximately 90% sensitive for excluding breast cancer.
Breast cancer is not a single entity but rather a heterogeneous group of numerous disease subtypes. Invasive breast cancer comprises the largest subgroup approximately 70% while ductal carcinoma in situ (DCIS) comprises 20%. MRI is currently the most sensitive imaging modality to identify most invasive breast cancers with published sensitivities ranging between 89% and 100%. The sensitivity for diagnosing noninvasive breast cancer called Ductal Carcinoma in Situ (DCIS) is somewhat lower but remarkably up to 40% of DCIS is diagnosed only with breast MRI.
The specificity of a breast MRI is improved when the information from the breast MRI exam is combined with information from a patient’s mammogram and ultrasound studies. It is for this reason a patient will receive a full mammographic and sonographic workup prior to a breast MRI exam. It is also possible a patient will be asked to return for additional mammographic and sonographic evaluation after the breast MRI exam even though a patient has had a complete workup prior to the MRI exam. This is because a directed mammogram or ultrasound study looking at a particular region can reveal more information than an exam looking at the entire breast.
Clinical Indications for breast mri
- Evaluate extent of disease in newly diagnosed breast cancer patients
- Response to chemotherapy for extensive breast cancers
- Postoperative evaluation for close or positive margins
- Evaluation of scar versus recurrent breast cancer
- Detection of occult primary tumors when presenting finding is an abnormal lymph node(s)
- High risk patients: American Cancer Society recommendations
For problem mammograms or equivocal clinical findings in select patients. This includes the diagnosis of lobular invasive cancer which is frequently difficult to diagnose.
Patients testing positive for the BRCA gene:
- First degree relative of BRCA gene mutation carrier
- Lifetime risk of 20 – 25% or greater including strong family history of breast or ovarian cancer
- Radiation to chest between ages 10 to 30 such as Hodgkins disease
- Rare syndromes associated with breast cancer
Breast Implant rupture
How is the procedure performed?
The breast MRI exam is performed in a large magnet which is like a very large tube. The patient lies on his or her stomach. The breasts hang into a cushioned opening on the table. The table moves freely into and out of the magnet. A contrast injection may be used. The contrast is administered through an intravenous catheter, which will be placed in a patient’s arm or hand by a technologist prior to the exam. The contrast agent, gadolinium, is generally very safe with very few side effects, but is not recommended for individuals with kidney failure.
Patients will be asked to lie very still while the machine acquires the images. It is extremely important not to move during the exam because motion during the exam causes image blurring and limits accurate interpretation of the exam. It is not uncommon to feel anxious about a breast MRI exam or feel uncomfortable because of the tight space of the magnet (claustrophobia). Short-acting anti-anxiety medication can be administered as a tablet prior to the exam. Anyone receiving anti-anxiety medication will need to have a friend or family member drive them home after the exam. Imaging is done in sequences, each lasting between one and fifteen minutes. When images are being acquired a tapping or thumping sound is heard. Head phones and music are offered to help dampen the noise. The imaging session lasts 30-45 minutes.