Echography of metastatic nodes treated by radiotherapy

The purpose of this study was to evaluate whether the ultrasonographic appearances of nodal metastases in nasopharyngeal carcinoma (NPC) revert to normal after radiotherapy. Serial ultrasonography was performed in 18 patients with palpable nodal metastases in the neck who underwent radiotherapy for NPC. All patients had a pre-radiotherapy baseline and another study at least one year after radiotherapy. The largest node in each patient was evaluated for any change in the ultrasonographic features following radiotherapy. One year after radiotherapy nodes returned to normal size for their respective areas, the shape of the node and the echogenic hilus also reverted to normal. However, the nodes are more echogenic than nodes in normal subjects. This distinguishes these nodes from nodes not affected by radiotherapy. The histological basis for this observation is presumed to be the result of fibrosis. At first glance the post-radiotherapy nodes may resemble normal nodes, however subtle changes within the node and adjacent soft tissues can be recognized on ultrasonography. During long-term follow-up, the appearance of nodes at sites previously uninvolved or any change in the appearance of nodes should alert the sonologist to the possibility of recurrence.