Surgical specimen ultrasound: is it able to predict the status of resection margins after breast-conserving surgery?

PURPOSE: To evaluate the accuracy of surgical specimen ultrasound in the assessment of the status of resection margins after breast-conserving surgery. METHODS AND MATERIALS: Sonographic examination of 46 surgical specimens of US-detectable malignant tumors was performed. Distance of the lesion from the specimen margins in four radial directions was measured and compared with distances measured on pathologic examination. Positive pathologic margins were defined when invasive or intraductal carcinoma was found within 2 mm of the specimen margin. Sensitivity, specificity, positive(PPV) and negative predictive values(NPV) of US in predicting surgical margins were calculated, considering both a 10-mm and a 4-mm sonographic threshold. RESULTS: Of 184 margins(4 per lesion), pathology demonstrated 28 positive and 156 negative margins. Considering the 10-mm cut-off, US identified 32 positive and 152 negative margins, showing the following sensitivity, specificity, PPV and NPV: 28.5%, 84.6%, 25% and 86.8%, respectively. Considering the 4-mm cut-off, US identified 7 positive and 177 negative margins, with a sensitivity of 7.1%, a specificity of 96.8%, a PPV of 28.2% and a NPV of 85.3%. False-negative results were more frequent in case of invasive lobular carcinoma (20%) and presence of intraductal component (60%). CONCLUSION: Sonography demonstrated a poor performance in the evaluation of the status of resection margins in breast specimens; however, because of the high NPV -both with 10-mm and 4-mm thresholds- it might be helpful in confirming complete excision of a US-detected neoplasm and in ruling out the presence of macroscopic invasive ductal carcinoma at surgical margins.