Pulmonary hilar lymph node metastases from lung cancer: evaluation based on morphology at thin-section, incremental, dynamic CT.

Abstract

To evaluate the usefulness of a new computed tomographic (CT) criterion for diagnosing hilar lymph node metastases on the basis of the margin between hilar interstitium and lung parenchyma. The morphology of normal and metastatic hilar nodes was analyzed in seven inflated and fixed human lung specimens. Thin-section, incremental, dynamic CT was then performed preoperatively in 95 patients with lung cancer, and the margins of peribronchovascular hypoattenuated areas were evaluated in 22 of the patients with normal hila. CT-pathologic comparisons were performed at 179 locations where interstitium touched lung parenchyma. The comparison was based on a new CT criterion in which convex interstitial margins indicate nodal metastases. The margins of the interstitia with normal nodes were concave or straight at 94.8% (183 of 193) of the contact sites in the six normal specimens and at 97.3% (436 of 448) of the contact sites on CT scans, whereas the margins of the interstitia with abnormal nodes were convex at 94.7% (54 of 57) of the contact sites in the abnormal specimen. Sensitivity, specificity, and accuracy of three reviewers who used the new criterion were 87.3%, 88.3%, and 88.1%, respectively. The new CT criterion is useful for the diagnosis of hilar node metastases in lung cancer.