Role of Preoperative Localization with Ultrasound in Thyroid Carcinoma Neck Lymphadenectomy

  Objective  To explore the role of preoperative localization of lymph nodes with ultrasound in thyroid carcinoma neck lymphadenectomy.

  Methods  Altogether 38 patients (89 located lymph nodes) who underwent thyroid carcinoma neck lymphadenectomy and preoperative localization of lymph nodes with ultrasound in the period from January 2012 to May 2015 in Peking Union Medical College Hospital were enrolled in this study. The location and the ultrasonic features of metastatic lymph nodes were retrospectively analyzed, the value of the ultrasonic features in diagnosis of metastatic lymph nodes was also evaluated.

  Results  The short-axis diameter of the 89 lymph nodes located with ultrasound was (0.59±0.25)cm. Twenty-three lymph nodes (25.9%) were located in level Ⅱ, 25 (28.1%) in level Ⅲ, 17 (19.1%) in level Ⅳ, 5 (5.6%) in level Ⅴ, and 19 (21.3%) in level Ⅵ. Surgery pathological findings confirmed that 80 of the 89 located lymph nodes were lymph nodes, of which 60 were metastatic and 20 were non-metastatic (8 inflammatory and 12 normal). No lymph node was found in the corresponding levels of 6 located lymph nodes. Two of the located lymph nodes were diagnosed as fibrous and nervous tissues and one as thymus tissue. There was significant difference in disordered blood flow between metastatic lymph nodes and non-metastatic lymph nodes (46.67% vs. 5.00%, P=0.001). The sensitivity and specificity of disordered blood flow in diagnosing metastatic lymph nodes were 46.67% and 95.00%, respectively. There was no significant difference in short-axis diameter (≥ 1 cm), short-to-long axis (S/L) ratio(≥ 0.5), unclear corticomedullary differentiation, thickened cortex, anechoic, strong echoic, and hyperechoic areas in cortex, peripheral blood flow or abundant blood flow between metastatic and non-metastatic lymph nodes.

  Conclusions  The lymph nodes located with preoperative ultrasound are usually too small to be palpated by surgeons. Preoperative localization with ultrasound of lymph nodes could guide the scope of operation and targeted dissection of metastatic lymph nodes. The disordered blood flow is specific in diagnosing metastatic lymph nodes, which could play an important role in preoperative localization of lymph nodes when combined with other ultrasonic features.