Tumor recurrence versus fibrosis in the irradiated breast: differentiation with dynamic gadolinium-enhanced MR imaging.

To assess the value of magnetic resonance (MR) imaging of the breast in the differentiation of late postirradiation fibrosis from recurrent carcinoma, 35 women with a history of breast carcinoma treated conservatively with radiation therapy underwent MR imaging. Nine patients had recurrent tumors confirmed at biopsy and surgery. Twenty-six patients had a localized fibrotic mass confirmed at biopsy and/or during long-term clinical and radiologic follow-up. In all cases, a localized hypointense area was present on plain spin-echo T1-weighted images. In all recurrent tumors, dynamic gadolinium-enhanced T1-weighted images demonstrated early increased signal intensity of the lesion within 3 minutes after bolus injection. The signal intensity over time in localized fibrosis differed from that in tumor recurrence, with no substantial enhancement on post-contrast T1-weighted images. Short inversion time inversion recovery and spin-echo T2-weighted images were not useful in the differential diagnosis of recurrent tumor versus radiation fibrosis.