Comparison of thyroid ultrasound results in the diagnosis of metastatic nodules from papillary thyroid cancer with postoperative pathology specimens

The aim of the present study is to determine the accuracy of ultrasound imaging in the diagnosis of metastatic lymph nodes compared to postoperative pathology samples of patients with papillary thyroid cancer.

This study was carried out using a descriptive and analytical epidemiological method on 103 known patients with papillary thyroid cancer who referred to Imam and Golestan hospitals in Ahvaz for neck ultrasound from September 2021 to August 2022. A total of 103 patients (including 94 women (91.3%) and 9 men (8.7%)) with papillary thyroid cancer with an average age of (39.8±11.9) were included in the study. The average tumor size in these patients was estimated to be (16.8±10mm). The ultrasound results of these patients before surgery were compared with the pathology results of these patients after surgery.

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.

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.