Background: When performing breast-conserving surgery (BCS), it is essential to achieve a complete resection of the tumor while preserving the cosmetic outcome. The aim of this study was to evaluate the accuracy of a MRI marking technique for planning of BCS.
Methods: A retrospective review was performed of 14 consecutive patients who underwent MRI in the supine position (supine MRI) using a MRI marking technique. The preoperative histopathological diagnosis was ductal carcinoma in situ in 11 and invasive ductal carcinoma in 3. All of the patients with invasive ductal carcinoma were treated with neoadjuvant chemotherapy. The pills of Breath Care used as MRI markers were placed in the Penrose drain with 2-cm intervals, and drains were put on the resection lines as determined by ultrasonography (US). The final resection lines were modified using information obtained by supine MRI. The rate of the margin-tumor distance (RMTD: longer margin-tumor distance/shorter margin-tumor distance) was calculated.
Results: Thirteen patients (93%) needed modification of the first resection line, whereas one patient (7%) needed no modification. Twelve patients (86%) had negative margins, but two patients (14%) had positive margins: one patient had a medial margin, while the other had a distal margin. One patient showed a pathologically complete response after chemotherapy; the RMTD was not evaluated. Among the 12 patients with medial and lateral negative margins, the medial and lateral margin-tumor distances ranged from 1.0 to 3.5 cm (average 2.1 cm), and the RMTD ranged from 1 to 3.0 (average 1.5).
Conclusion: Our MRI marking technique may be useful for evaluating the extent of the tumor as determined by the US examination in difficult cases.