Abstract
We report the imaging procedures used in our department and diagnostic criteria of ultrasonography for detecting cervical lymph node metastasis from oral cancer. Our diagnostic criteria for B-mode US are: (1) lymph nodes with definite internal echoes are considered metastatic; (2) lymph nodes with hilar echoes are considered benign; (3) lymph nodes with long/short-axis ratios of ≥3.5 are considered benign. B-mode US is 66% sensitive and 98% positive predictor value in detecting metastasis. Our diagnostic criteria for Doppler US findings are: (1) lymph nodes with scattered blood flow signals in their parenchyma are considered metastatic; (2) lymph nodes with blood flow signals along their periphery are considered metastatic; and (3) lymph nodes with hilar signals branching radially from the hilus are considered benign. Overall sensitivity for combined B-mode with Doppler US was 84.1% which was significantly better than that for B-mode US alone. However, diagnostic accuracy depends on lymph node size. We therefore consider that vascularity within metastatic lymph nodes changes according to lymph node size and increases with angiogenesis during early-stage metastasis, which can be shown on Doppler US images. Increased blood flow in the parenchyma was a characteristic of Doppler US findings in small lymph nodes during early-stage metastasis. As the size of metastatic lymph nodes increased, blood flow signals became more scattered.
Follow-up US at four-week intervals is recommended at least during the first posttherapeutic year.
Doppler images on the invasion front of the tongue cancer are predictors of the pathological grade of malignancy and cervical lymph node metastasis.
