MR imaging of the breast after surgery for breast cancer

Unenhanced scans, with any sequence, often give limited and unreliable information when trying to distinguish tumor recurrence from scarring. Dynamic scanning very soon after the intravenous injection of Gd-DTPA is the best available method of distinguishing between benign tissue and neoplastic recurrence after conservation treatment for breast cancer. 3-D T1-weighted gradient echo images appear to be the technique of choice, preferably with image subtraction. Rapid and pronounced tissue enhancement is strongly suggestive of tumor recurrence; however, scanning within 6 months of surgery and 9 months of radiation therapy may lead to false-positive results. Benign proliferative disease and recent fat necrosis may also mimic cancer on dynamic contrast enhanced MR images. The indications for MR imaging after tylectomy and radiotherapy are findings that are equivocal or suspicious of neoplastic recurrence on clinical examination, mammography, or ultrasound, often on a combination of these modalities. Typical clinical findings are a mass or induration at the site of surgery, a mass lesion with spiculated and irregular outline on mammography, or variable echogenicity on ultrasound. The development of these appearances on sequential examination is particularly suggestive of recurrence. When microcalcification is the only finding of a carcinoma on mammography after treatment for breast cancer, contrast enhancement is consistently present.