Preoperative breast MRI features associated with positive or close margins in breast-conserving surgery

To determine preoperative magnetic resonance imaging (MRI) features associated with positive or close margins in patients with breast cancer who underwent breast-conserving surgery (BCS).

A retrospective review identified 249 patients with invasive ductal carcinoma (IDC) who underwent preoperative MRI and BCS as a primary procedure between 2008 and 2010. The MR images were reviewed for descriptions of findings with no new interpretations made. Margins were defined as positive (tumor touching the inked specimen margin), close (<2 mm tumor-free margin), or negative (≥2 mm tumor-free margin). Multivariate logistic regression analysis was performed to evaluate imaging and clinical factors predictive of positive or close margins.

Of the 249 patients, 83 (33.3%) had positive or close margins and 166 (66.7%) had negative margins on the initial BCS specimen. Multivariate analysis showed that multifocal disease (odds ratio, 4.8; 95% CI, 1.9-12.2; p =  0.001), nonmass enhancement lesion (odds ratio, 3.0; 95% CI, 1.5-6.2, p =  0.003), greater background parenchymal enhancement (odds ratio, 2.5; 95% CI, 1.1-5.6; p =  0.023), larger lesion size (odds ratio, 1.3; 95% CI, 1.0-1.7, p =  0.032), and presence of ductal carcinoma in situ on needle biopsy (odds ratio, 2.4; 95% CI, 1.3-4.6; p = 0.008) were independent predictors of positive or close margins.

Multifocal disease, nonmass enhancement lesion, or greater background parenchymal enhancement on preoperative breast MRI were significantly associated with positive or close margins. Identifying these MRI features before surgery can be helpful to reduce the reoperation rate in BCS.