Which changes on magnetic resonance mammography (breast MRI) are seen following radiation therapy?

Updated: Feb 25, 2019
  • Author: Preeti Gupta, MD, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Diffuse skin thickening, fibrosis leading to a smaller breast, and trabecular thickening are common findings after radiation. Fibrosis can have a spiculated masslike appearance but shows no or minimal enhancement.

In the first 12 months after radiation therapy, a diffuse increase in capillary permeability occurs. This change can cause marked parenchymal enhancement that later becomes patchy. In most women, this enhancement gradually declines after 18 months because of fibrosis. [73] As a result, after radiation, there is usually minimal background enhancement, less than the normal contralateral breast. Any enhancing lesion on this background is suggestive of a recurrent tumor. [74]

Some patients may need breast MRI soon after surgery and radiation therapy, if the presence of residual disease is strongly suspected. Although diffuse parenchymal enhancement is of little diagnostic value, the demonstration of typically malignant enhancement in a focal lesion should prompt repeat excision.

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