These imaging tests are usually already completed as part of the diagnostic workup (prior to pathological diagnosis). However, mammography is limited by breast density. In a prospective study of 111 consecutive women with newly diagnosed breast cancer, sensitivity of 2-D mammography for malignancy decreased from 100% in breasts that are almost entirely fatty to 45% in extremely dense breasts [22]. In addition, 2-D mammography was more sensitive than US in detecting DCIS and less sensitive at detecting ILC. DBT shows higher overall sensitivity, compared with 2-D mammography, with similar specificity. Overall sensitivity for DBT was 88.2% compared with 78.3% for 2-D mammography [23]. DBT also has a higher sensitivity for detecting multifocal, multicentric, and contralateral breast cancer [24,25]. The improved diagnostic performance of DBT over 2-D mammography was limited to women with nondense breasts in 1 study [24], but not others [25]. Due to patient positioning constraints, 2-D mammography and DBT have limited value for evaluating the axilla. In a single-institution retrospective study of 3,944 patients with breast cancer, mammography improved the sensitivity over US alone for distinguishing N0 to N1 from N2 and N3, but at a lower specificity [35]. After the ACOSOG Z0011 trial supported the omission of axillary lymph node dissection in women with <3 positive sentinel lymph nodes undergoing breast-conserving surgery and radiation therapy, some providers may request that radiologists not image the axilla in the setting of clinically node-negative disease [36]. Although axillary US is not recommended for every patient [37], axillary abnormality visible on mammography is still considered an appropriate indication for sonographic axillary evaluation. Also, when neoadjuvant chemotherapy is planned, the NCCN recommends consideration of axillary US, with marker placement if a biopsy is performed, in addition to mammography [126].
Imaging of Invasive Breast Cancer. These imaging tests are usually already completed as part of the diagnostic workup (prior to pathological diagnosis). However, mammography is limited by breast density. In a prospective study of 111 consecutive women with newly diagnosed breast cancer, sensitivity of 2-D mammography for malignancy decreased from 100% in breasts that are almost entirely fatty to 45% in extremely dense breasts [22]. In addition, 2-D mammography was more sensitive than US in detecting DCIS and less sensitive at detecting ILC. DBT shows higher overall sensitivity, compared with 2-D mammography, with similar specificity. Overall sensitivity for DBT was 88.2% compared with 78.3% for 2-D mammography [23]. DBT also has a higher sensitivity for detecting multifocal, multicentric, and contralateral breast cancer [24,25]. The improved diagnostic performance of DBT over 2-D mammography was limited to women with nondense breasts in 1 study [24], but not others [25]. Due to patient positioning constraints, 2-D mammography and DBT have limited value for evaluating the axilla. In a single-institution retrospective study of 3,944 patients with breast cancer, mammography improved the sensitivity over US alone for distinguishing N0 to N1 from N2 and N3, but at a lower specificity [35]. After the ACOSOG Z0011 trial supported the omission of axillary lymph node dissection in women with <3 positive sentinel lymph nodes undergoing breast-conserving surgery and radiation therapy, some providers may request that radiologists not image the axilla in the setting of clinically node-negative disease [36]. Although axillary US is not recommended for every patient [37], axillary abnormality visible on mammography is still considered an appropriate indication for sonographic axillary evaluation. Also, when neoadjuvant chemotherapy is planned, the NCCN recommends consideration of axillary US, with marker placement if a biopsy is performed, in addition to mammography [126].