Abstract
Objective
To understand the changes in the sonographic findings of the lymph nodes before preoperative radiotherapy and after preoperative radiotherapy. In addition, we also evaluated the contribution of irradiation for prediction cervical lymph node metastasis.
Materials and Methods
We performed US examinations on 166 cervical lymph nodes (64 metastatic and 102reactive nodes) before and after radiotherapy. We also evaluated the pattern of vascularity and found it to be divided into 3 categories; a hilar pattern, a peripheral pattern and a no-signal pattern. Both previous report and our previous study supported the theory that either the displaced hilar flow or the absence of local perfusion indicates a malignant nature of lymph nodes and therefore, w e evaluated any abnormalities in a hilar pattern.
Results
Irradiation of the neck (22.5Gy or 30Gy) caused an increase of blood inflow into the lymph nodes and better visualization of the peripheral vessels. The incidence of a no-signal pattern decreased from 27% before irradiation to 7% after irradiation. Preoperative irradiation improved the detection of an abnormal hilar flow in the metastatic nodes and the incidence increased from 45% to 74%. If an abnormal blood flow (a no-signal pattern, a peripheral pattern and an abnormal hilar pattern) was a criterion for metastasis, the discriminative power was increased with sensitivity from 72% to 86%, specificity from 64% to 89%.
Conclusion
After irradiation, the reduction of percentage of reactive nodes of no-signal pattern and the better detection of an abnormal hilar flow in metastatic nodes improved the discriminative power.
