Dynamic MRI of breast hardness following radiation treatment

To evaluate functional microvascular characteristics of breast induration several years after radiation treatment using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) techniques.

Fifteen women with moderate or marked breast induration after surgery and radiotherapy for breast cancer (2-15 years) were examined. Images of the irradiated breast (boost and nonboost sites) on short tau inversion recovery (STIR) and DCE-MRI sequences were subjectively evaluated for edema and the presence of enhancement and compared to the contralateral normal breast. Quantitative enhancement parameters-percent enhancing pixels, transfer constant (K(trans)), rate constant (k(ep)), leakage space (v(e)), and maximum contrast medium accumulation (MCMA)-were also compared.

No tumor recurrence was seen. Fat necrosis was seen in 2/15 cases. Increased parenchymal edema at the electron boost site was seen in 12/14 patients. Greater enhancement in the irradiated breast was seen in 11/14 evaluable patients. Kinetic parameter estimates including K(trans) were similar except for percent enhancing pixels, which was greater in the irradiated breast at both boost and nonboost sites (P = 0.03 and 0.04, respectively). v(e) and MCMA estimates were greater in breasts with marked induration compared to moderate grades (P = 0.002 and 0.01, respectively).

Parenchymal edema may be an important contributor to palpable induration several years after breast radiotherapy. Increased fluid content may be related to increased numbers of perfused microvessels and/or impaired lymphatic drainage.