Magnetic resonance imaging in size assessment of invasive breast carcinoma with an extensive intraductal component

BACKGROUND: Breast-conserving treatment of invasive breast carcinoma with an extensive intraductal component (EIC) is associated with DCIS-involved surgical margins and therefore it has an increased recurrence rate. EIC is a non-palpable lesion of which the size is frequently underestimated on mammography. This study was undertaken to evaluate the accuracy of MRI in size assessment of breast cancer with EIC. METHODS: 23 patients were identified and the mammographic (n = 21) and MR (n = 23) images were re-reviewed by a senior radiologist. Size on MR images was compared with histopathological tumour extent. RESULTS: The correlation of radiological size with histopathological size was r = 0.20 in mammography (p = 0.39) compared to r = 0.65 in MRI (p < 0.01). Mammography underestimated histopathological tumour size in 62%. MR images over- or underestimated tumour size in 22% and 30% of the cases, respectively. In poorly differentiated EIC, MRI adequately estimated the extent more often compared to moderately differentiated EIC (60% versus 25%, respectively). CONCLUSION: Size assessment of MRI imaging was more accurate compared to mammography. This was predominantly true for poorly differentiated EIC.