Results: According to the obtained results, metastatic involvement of cervical lymph nodes was diagnosed in 36.6% of patients (38 people). Of these, 30.7% of patients (32 people) were real positive. The results of ultrasound before surgery were shown as false positive in 9.5% of patients (6 people). Lymphatic metastasis was not seen in 58.4% of patients (60 people) before surgery, which was consistent with the pathology result after surgery (true negative). The positive predictive value of examining metastatic lymph nodes by ultrasound was estimated at 84.2% and the negative predictive value at 92.3%. The diagnostic accuracy of ultrasound was 89%, the sensitivity rate was 86%, and the specificity rate was 90% with the area under the curve AUC=0.884 and P<0.001. Ultrasound accuracy is not affected by tumor size, Hashimoto's thyroiditis and metastasis location (P<0.05). In patients with Hashimoto's thyroiditis, the tumor size increases significantly more than 10 mm.
Conclusion: Ultrasound alone has an acceptable diagnostic accuracy in detecting metastatic lymph nodes caused by papillary thyroid cancer. However, the incidence of false negative error increases as the tumor size decreases.
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