SUNDAY, 11/28/99 ~ EVENING EDITION
Multimodality algorithm evaluates postoperative breast cancer

By Brenda Tilke


Changes in breast tissue following lumpectomy or biopsy can mimic malignancy, creating challenges in postoperative breast imaging. Radiologists must learn to recognize which changes are associated with recovery from procedures and which changes are in fact early signs of new or recurrent cancer.

A team of radiologists at the University of Wisconsin in Madison reviewed some of the most common postoperative changes in breast tissue, presenting their findings in a scientific exhibit Sunday at the RSNA meeting. They developed an algorithm to evaluate the postoperative breast using ultrasound, CT, and MRI as complementary imaging modalities for difficult cases.



On the exhibit floor, a representative for PlanMed demonstrates mammography compression using a foam football.

Among the changes that can be seen in the breast after a procedure are soft-tissue defects and fluid collections, especially after lumpectomy. The fluid collection usually decreases over time and tends to disappear completely, although it may still be seen on mammograms for up to five years.

Often scarring replaces the initial changes, generally within six to 18 months.

Radiation therapy also can cause changes in the breast tissue, with the most common being calcifications that are associated with fat necrosis. Sutures also can calcify. According to the Wisconsin team, as many as half of irradiated breasts may show such calcifications between two and five years after treatment. Scars and fat necrosis can show intense shadowing on sonograms and may seem to appear as a malignancy. If these findings appear on only one projection, then a contrast-enhanced MR scan can be useful.

MRI performed early after surgery, however, may result in falsely positive enhancement due to inflammatory changes during healing.

Cysts often develop after breast procedures. A complex cystic mass with no blood flow is part of the normal postoperative course, according to the team led by Dr. Pamela A. Propeck. If the mass is solid or shows blood flow, then tissue sampling is warranted.