MRI added to mammography identifies most ductal components of invasive breast cancer

Magnetic resonance imaging (MRI) is superior to mammography alone in diagnosing intraductal components of invasive breast cancer, allowing more accurate mapping before breast conservation surgery, said Simone Schrading, MD, Department of Radiology, University of Bonn, Germany.

Dr Schrading's study included 139 women (mean age, 54 y) who had invasive breast cancer with additional intraductal components. All women underwent bilateral mammography and high-resolution bilateral breast MRI.

The overall sensitivity for identifying intraductal components was 85% for MRI and 37% for mammography alone. Thirty-four percent of intraductal components were identified by both imaging modalities. In 3%, only mammography was positive (false negative with MRI) and in 51%, only MRI was positive (false negative with mammography). Twelve percent of intraductal components were not identified by either imaging test.

By combining mammography and MRI, 88% of intraductal components were identified.

The sensitivity of MRI was independent of breast density. In American College of Radiology (ACR) type 1 breast tissue (lowest density), the sensitivity of MRI was 83%. In ACR 2, ACR 3, and ACR 4 (highest density) breast tissue, the corresponding sensitivity rates of MRI were 88%, 79%, and 92%, respectively.

The histology of the cancer did not influence the detection rate of intraductal components with MRI: sensitivity was 85% in ductal tumors, 83% in lobular tumors, and 87% in ductal-lobular tumors.

Tumor grade also did not influence the sensitivity of MRI: sensitivity was 82% in non-high-grade invasive tumors and 86% in high-grade invasive tumors.

"There were no subgroups that did not profit from preoperative breast MRI for diagnosing intraductal components," said Dr Schrading.

Other subgroups examined were based on age, familial risk of breast cancer, and personal history of breast cancer.