Detection of internal mammary lymph node enlargement: comparison of CT scans and conventional roentgenograms

Sixty-two patients with breast cancer had thoracic computed tomography (CT) scans and conventional chest radiographic (CXR) examinations separated by an average of 29 days. CT served as the gold standard showing 13 cases with enlarged internal mammary nodes 0.4 to 7 cm in diameter. Original CXR interpretations were available. Additionally, these films were reinterpreted, without knowledge of the CT results, with special attention to the retrosternal region on the lateral film including the use of a bright light and comparison to prior lateral views. Original CXR interpretations detected only one (7 cm) enlarged node. Sensitivity was 8% and specificity 100%. Reinterpretation of the CXRs, without knowledge of the CT results, with special attention to the retrosternal region yielded five true positive and seven false positive determinations for a sensitivity of 38% and specificity of 86%. No enlarged node under 2.5 cm in diameter was detected on CXR. Sensitivity of CXR can be considerably improved by careful evaluation of the retrosternal space, but at the cost of considerable increase in false positive examinations. CT is necessary to achieve reasonable sensitivity and specificity in the detection of internal mammary lymphadenopathy.