BREAST CANCER SCREENING – Practical applications of breast MRI
-Jennifer Kam Ray, M.D.
Breast MRI is a highly sensitive, but not very specific modality for the evaluation and treatment of breast disease. Historically, it was used exclusively in academic centers but has now become more readily available for routine clinical use. MRI has the ability
to image in three dimensions and provides good physiologic and morphologic information. MRI provides unique
information that helps women and their surgeons make better treatment decisions.
MRI should not be used to distinguish a benign from a malignant process or to preclude biopsy of a clinically suspicious lesion. In
carefully selected cases, MRI may be helpful in clarifying equivocal or suspicious mammographic findings. Detailed mammographic
evaluation and ultrasound must be performed first. In high-risk patients, MRI has been shown to be a useful adjunctive screening tool. “High-risk” is defined by one of the following, according to most insurance carriers:
- Confirmed presence of BRCA1 or BRCA2 mutation
- First degree blood relative with BRCA1 or BRCA2 mutation and are untested
- Have a lifetime risk of breast cancer of 20-25 percent or more using standard risk assessment models (BRCAPRO, Claus model, Gail model, or Tyrer-Cuzick)
- Carry or have a first-degree relative who carries a genetic mutation in the TP53 or PTEN genes (Li-Fraumeni syndrome and Cowden and Bannayan-Riley-Ruvalcaba syndromes)
- Received radiation treatment to the chest between ages 10 and 30 years, such as for Hodgkin’s disease
Nearly all patients who have biopsy proven breast carcinoma will benefit from a “planning MRI” prior to surgery. Feedback from surgeons suggests that an MRI prior to surgery helps reduce the number of positive or inadequate margins on difficult tumors such as ductal carcinoma in situ (DCIS) and lobular cancers. Lobular cancer is frequently multifocal and multicentric and often bilateral. The extent of disease can be accurately assessed in most cases, and surgical planning can be optimized for the patient.
MRI can be useful in detecting occult cancers. About 0.3% of patients present with malignant axillary lymph nodes but have normal mammograms and physical examinations. In the past, the standard treatment of these patients has been mastectomy. MRI often detects multifocal, multicentric, or bilateral cancers. The exam itself takes approximately 45 minutes. The patient is in a prone position in a dedicated breast coil and is required to receive intravenous gadolinium. If claustrophobia is an issue, sedation is available. MRI can also be used to evaluate the integrity of breast implants. For this examination, contrast is unnecessary. Suspected intra and extracapsular implant rupture are approved indications for breast MRI.