Ultrasonographic demonstration of retropharyngeal lymph nodes: preliminary report.

The aim of this study was to describe the results of ultrasonography of upper retropharyngeal lymph node (RPN) metastasis in patients with pharyngeal carcinomas. A total of 10 patients with metastatic RPN were examined using percutaneous ultrasound (US) with 3.5-MHz probes. Primary cancer sites were the nasopharynx in two patients, the oropharynx in three and the hypopharynx in five. Metastatic RPNs lay in the level of occipital bone in five patients, C1 in nine, and C2 in five. US images were compared with previously obtained computerized tomography (CT) images based on size and depth. In all of the 10 patients, metastatic RPNs were ultrasonographically demonstrated as hypoechoic masses. Nodal sizes ranged from 1.5 cm to 3.5 cm both in CT and in US. Depths of the RPN centers were from 3.5 cm to 7.0 cm in CT, and from 3.5 cm to 6.5 cm in US. Differences of sizes and depths between CT and US were from -0.5 cm to 0.5 cm and from 0.0 cm to 1.0 cm, respectively. RPNs that are 1.5 cm or more in size can be demonstrated with percutaneous US using CT guidance. This technique should be utilized for the purpose of monitoring in a radiation therapy setting.