Computed tomography and ultrasonography of metastatic cervical lymph nodesin oral squamous cell carcinoma

Objectives: To define criteria for CT and US in differentiating cervical ly mph node metastases in oral squamous cell carcinoma (SCC). Materials and methods: CT and/or US of 230 metastatic lymph nodes and 228 b enign lymph nodes in 147 patients with oral SCC were retrospectively evalua ted. The CT and US findings of each lymph node were compared with the histo pathological findings. A metastasis was defined on Ci as a lymph node with rim or heterogeneous enhancement, or measuring 10 mm or more in the short a xis. regardless of enhancement pattern, and on US as having definite intern al echoes. regardless of size, or without definite internal or hilar echoes , but measuring 10 mm or more in the short axis. A lymph node with hilar ec hoes or a ratio of the long to short axis (L/S ratio, of 3.5 or more was co nsidered benign. A lymph node failing to conform to any of these categories was termed questionable. Results: The positive predictive value (PPV) for CT was 90.8% and the negat ive predictive value (NPV) was 70.4%. However, 65.7% of all lymph nodes cou ld not be classified as either metastastic or benign. PPV for US was 96.5% and NPV was 88.1%. 25.5% of all lymph nodes could not be classified as eith er metastatic or benign. Conclusions: Despite limitations in detecting metastses, by including a thi rd category 'questionable' our criteria appear clinically more useful than other current methods based on two groups only.