Ultrasonographic evaluation of metastatic cervical lymph nodes in head and neck cancers

Abstract

This study evaluates the use of ultrasonography (USG) to diagnose metastatic cervical lymph nodes. Three-hundred and one lymph nodes were removed from 58 patients with squamous cell carcinomas of the head and neck. None of the patients had received any preoperative treatments for cancer. The lymph nodes were then histopathologically examined: 139 metastatic lymph nodes and 162 non-metastatic nodes were found. USG was then used to evaluate the size, internal echo, and margin of each lymph node. Size was found to be the best criteria for distinguishing metastatic lymph nodes from non-metastatic lymph nodes in all cervical regions (78% accuracy). Superior internal jugular lymph nodes and submandibular lymph nodes larger than 7 mm and mid and inferior internal jugular lymph nodes larger than 6 mm were regarded as metastatic. Internal echoes were classified into five patterns: homogeneous hypoechoic, homogeneous hyperechoic, heterogeneous, eccentric hyperechoic, and centric hyperechoic. Homogeneous hyperechoic and heterogeneous patterns were characteristic of metastatic nodes, while eccentric hyperechoic patterns were characteristic of non-metastatic nodes. Homogeneous hypoechoic patterns were observed in both metastatic and non-metastatic nodes. Regular margins were found in 81% of the metastatic nodes. Of the 22 lymph nodes with irregular margins, however, 91% were metastatic. Evaluations using a combination of USG and clinical feature criteria were compared with evaluations using only thickness as a criterium. Although thickness is the single most important factor in diagnosing metastatic nodes, the combination of USG and clinical feature criteria improved the accuracy of diagnosis to 83%. Thus, diagnostic methods involving a combination of several criteria are more accurate than methods involving only a single criterium.