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

Abstract

Purpose: 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).

Materials and methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Breast cancer; Breast-conserving surgery; Preoperative MRI; Resection margins.

Fig. 1.

Graph shows the receiver operating characteristic curve for the multivariate model.

Fig. 2.

45-year-old woman with breast cancer and positive surgical margins. Sagittal T1-weighted fat-suppressed postcontrast (A and B) and sagittal subtraction maximum intensity projection (C) MR images of left breast show 3 cm clumped nonmass enhancement containing the signal void artifact from a biopsy clip (arrows) and multifocal disease (arrowheads) in the upper outer quadrant. Invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS) were diagnosed in the biopsy specimen. Patient underwent MR-guided needle localization. Surgical margins were focally positive for IDC and DCIS. Pathology revealed three foci of IDC.

Fig. 3.

58-year-old woman with breast cancer and negative surgical margins. Sagittal T1-weighted fat-suppressed postcontrast (A), sagittal postcontrast subtraction (B), and sagittal subtraction maximum intensity projection (C) MR images of left breast show 1.5 cm irregular enhancing mass (arrows) in the lower outer quadrant. There is no evidence of multifocal disease. Absence of ductal carcinoma in situ was noted in the biopsy specimen. Pathology revealed unifocal invasive ductal carcinoma with negative surgical margins.