Patterns of internal echoes in lymph nodes in the diagnosis of lung cancer metastasis.

In 1989-90, all 37 lung cancer patients scheduled for surgery underwent transesophageal endoscopic ultrasonography (EUS) for pre-operative detection of hilar and mediastinal lymph node metastases. An electronic ultrasonic fiberscope with a linear array (EPB-503-FS, Machida-Toshiba) was used. Of 380 nodes surgically removed and that could have been detected by EUS, the detection rates for histologically metastatic and non-metastatic nodes were 65% (33 of 51) and 44% (144 of 329), respectively (p less than 0.01). Metastatic nodes were detected readily in every lymph node site, especially subaortic and subcarinal. Non-metastatic nodes were detected at low rates, especially in the superior mediastinum, paratracheal, and tracheobronchial locations. For greater long or short axes of the detected nodes, or for rounder nodes, the metastasis rate was higher. Detected nodes were classified into six types by their internal echo patterns; three were rarely metastatic (called "negative") and the other three were often metastatic (called "positive"). Of the "negative" nodes histologically proved to be metastatic, metastasis was often diffuse. The "positive" nodes found to be metastatic tended to have one of two patterns of internal echoes when invasion was diffuse and a third pattern when it was localized. In an examination of the diagnostic usefulness of EUS, we made more correct diagnoses from the internal echo pattern than by reference to either the long or short axis alone. The short axes, node shape, and internal echoes were examined by Hayashi's second method of quantification. The sensitivity, specificity, and accuracy of the diagnoses were 85%, 84%, and 84%, respectively, superior to those by computed tomography done of the same patients.