Introduction: The accuracy of breast magnetic resonance imaging (MRI) for detection of ductal carcinoma in situ (DCIS) has prompted recommendations for its routine preoperative use, but its clinical benefit is debated. We reviewed our experience with MRI in DCIS patients to assess the utility of MRI for surgical planning. Methods: DCIS patients (2008-2010) were identified through a prospectively maintained database and grouped into MRI and no-MRI groups. The rates of additional biopsies, altered surgical management, and reoperation were compared. Additionally, DCIS size ascertained by mammography, MRI, and final pathology was compared. Results:: Of 352 DCIS patients, 217 received MRI and 135 did not. The type of initial operation and number of reoperations were similar between the two groups, but successful breast conservation was more frequent in the no-MRI group (p = 0.06). The additional biopsy rate was 38 % in the MRI group versus 7 % in the no-MRI group; ≥2 additional biopsies were performed in 18 % of the MRI group and 2 % of the no-MRI group (p < 0.0001). These yielded a cancer diagnosis in 26 % of MRI and 33 % of no-MRI patients (p = 0.73). MRI was not superior to mammogram in detecting size of DCIS lesions preoperatively; 52 % of mammograms were accurate (within 1 cm) compared with 41 % of MRIs. Conclusions: DCIS patients who undergo preoperative breast MRI are far more likely to undergo additional biopsies. Unless these can be demonstrated to lead to improved long-term outcomes, the utility of routine preoperative MRI in DCIS patients remains questionable.
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