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[Preoperative dynamic contrast-enhanced MRI can reduce the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma].

Objective: To investigate the value of preoperative dynamic contrast-enhanced MRI in reducing the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma. Methods: Seventy-two patients with early non-mass breast carcinoma received ultrasonographic and mammographic examination and subsequently underwent dynamic contrast-enhanced MRI examination before breast conserving surgery. The control group consisted of 74 patients who had early non-mass breast carcinoma. They only received ultrasonographic and mammographic examination and didn't undergo contrast-enhanced MRI examination. The comparison of the rate of tumor-positive resection margins between two groups was performed. The MRI findings that had the significant influence on the rate of tumor-positive resection margins were analyzed using Logistic regression model. Results: In 28 patients (28/72, 38.9%), dynamic contrast-enhanced MRI could correct or supplement the ultrasonographic and mammographic findings and resulted in the reasonable change of surgical program. The preoperative MRI examination group (n=30) had lower rate of tumor-positive resection margins than control group for invasive ductal carcinoma (23.3% vs 40.0%, P=0.02), but there was no significant difference (21.4% vs 26.9%, P=0.10) between two groups for ductal carcinoma in situ (n=28). The preoperative MRI examination group (n=14) had lower rate of tumor-positive resection margins than control group for the other pathologic types of breast carcinoma (14.3% vs 38.9%, P=0.02). The statistical analysis on the basis of Logistic regression model showed that some main MRI findings, including change surrounding the tumor, distance between tumor and nipple and tumor size, had the significant influence on the rate of tumor-positive resection margins. Conclusion: Preoperative dynamic contrast-enhanced MRI significantly increased the accuracy of resection margins evaluation, and greatly reduced the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma.