MR imaging of ductal carcinoma in situ.

PURPOSE: To investigate the ability of magnetic resonance (MR) imaging to depict ductal carcinoma in situ (DCIS). MATERIALS AND METHODS: Between January 1992 and April 1996, 330 women underwent MR imaging before excisional biopsy. Of these, 101 women had carcinoma, 19 of whom had DCIS. The MR imaging findings in the 19 women were reviewed. RESULTS: Thirteen of 19 patients had pure DCIS. The mean lesion diameter was 10 mm (range, 2-22 mm). MR imaging enabled identification of DCIS in 10 (77%) of the 13 cases as ductal enhancement (n = 6), regional enhancement (n = 3), or a peripherally enhancing mass (n = 1). The three lesions not identified had a mean diameter of 3.7 mm. Six of 19 patients had both DCIS and an invasive cancer. In four of these patients, DCIS was identified only at MR imaging (mean diameter, 3 mm). In two of six patients, DCIS was not identified at MR imaging. CONCLUSION: MR imaging can depict mammographically visible and occult foci of DCIS. Some small foci of DCIS detected at mammography and histologic examination, however, may be occult at MR imaging.