The suggestion for standard scanning procedures of ultrasonographic examinations when surveying cervical lymph nodes in patients with oral squamous cell carcinoma

In our previous study, we elucidated that scans that included the thyroid gland should be performed when surveying the cervical lymph nodes for metastasis during ultrasonographic (US) examinations in patients with oral squamous cell carcinoma (SCC). However, no standard procedures have yet been established for US examinations to survey the cervical lymph nodes in patients with oral SCC. Therefore, we developed a standard US procedure and evaluated the legitimacy and drawbacks associated with it. For our US scan procedure to survey cervical lymph nodes in patients with oral SCC, five axial, two cross-sectional, and one coronal tomographic scan using a probe with a major axis of 10 cm and a minor axis of 2 cm were used for the lateral necks of Japanese patients. If the resulting images were thought to be insufficient by the examiner, then some additional and repeated US examinations were performed. In the present study, we analyzed the detection rates of cervical lymph nodes with a major axis over 8 mm using our US procedure for patients with oral SCC as a gold standard, using both magnetic resonance (MR) images and computed tomography (CT) images, which were obtained by both an expert and by a less-experienced examiner to examine how difficult the procedure was to follow and how accurate the results were. At the same time, the mean scanning hours spent by the expert and less-experienced examiner per patient was assessed when using our US procedure. In addition, the ink-smeared areas on the volunteer's neck as a result of our US procedure were analyzed. The detection rates of enlarged cervical lymph nodes using our US procedure were almost 95% for both the expert and the less-experienced examiner. In addition, the overlapped area of ink smeared on a standard volunteer's neck using our standard US procedure perfectly matched the lymph nodes in the cervical areas and thyroid glands. The time spent scanning the patients by the expert ranges from fifteen to twenty minutes, but the less-experienced examiner spent from twenty to twenty-five minutes per patient. Therefore, our US procedure for surveying the cervical lymph nodes, including thyroid glands, in patients with oral SCC can be recommended as a relatively good method, but inexperienced examiners should be prepared to spend additional time analyzing the scans.