The sonographic appearance and significance of cervical metastatic nodes following radiotherapy for nasopharyngaeal carcinoma

Serial ultrasound (US) was performed on 36 patients with palpable malignant nodes in the neck who had radiotherapy for nasopharyngeal carcinoma (NPC). All patients had a preradiotherapy baseline US examination, and follow-up studies at least 8 weeks after radiotherapy (RT). After RT there was diminution in size and disappearance of some of the nodes. However, in the residual nodes, US criteria for malignant nodes were still present in many of the post RT nodes, i.e. 140/143 (97.9%) residual nodes had an absent hilus and all the nodes were poorly reflective, 122 (85.3%) nodes still had sharp borders, 53 (37.1%) had a short to long axis (S/L) ratio greater than 0.5 and 11 (7.7%) nodes were greater than 8 mm in size. These parameters therefore are not of value in determining the persistence or recurrence of disease in a previously abnormal node. Appreciation of this fact should prevent unnecessary fine needle aspiration of these nodes up to 3 months following radiotherapy.