Effectiveness of contrast-enhanced ultrasound quantitative analysis in the diagnosis of cervical lymph node metastasis in patients with papillary thyroid carcinoma

Objective To explore the effectiveness of contrast-enhanced ultrasound (CEUS) quantitative analysis in the diagnosis of cervical lymph node metastasis in patients with papillary thyroid cancer (PTC). Methods A retrospective analysis was made on 90 patients with PTC who underwent surgical treatment in our hospital from January 2017 to January 2018. The patients were divided into metastasis group (40 cases) and non-metastasis group (50 cases) according to whether cervical lymph node metastasis occurred after operation. The size of cancer nodules, CEUS characteristics (perfusion intensity, uniform intensity, perfusion defect and perfusion mode), CEUS quantitative parameters [rise time (RT), Peak intensity (PI), mean transit time (MTT), area under curve (AUC), peak halving time (TPH), wash in slope (WIS) and time to peak (TTP)] were compared between the two groups. The ROC curve was used to analyze the diagnostic value of CEUS related indicators for different cut-off values. Results Seventy-six percent of 100 cancer nodules showed low enhancement, 89.00% showed non-uniform perfusion intensity, and the size of cancer nodules in metastatic group was significantly higher than that in non-metastatic group (P=0.002). PI, AUC and WIS in the marginal area of cancer nodules in the two groups were significantly higher than those in central area (all P<0.05), while PI, AUC in the marginal area in the metastatic group were significantly higher than those in the non-metastatic group (all P<0.001). The ROC curve showed that the edge AUC, edge PI and AUC of nodule size were 0.866, 0.869 and 0.720, respectively. The diagnostic efficiency of the edge AUC and PI for cervical lymph node metastasis was higher than that of the size of the cancer nodule (P=0.026, 0.018). Youden index indicated that the accuracy, sensitivity and negative predictive value of edge AUC and edge PI were significantly higher than those of nodule size at the best cut-off point (P_AUC = 0.042, 0.001, 0.019, P_PI= 0.018, 0.003, 0.022). Conclusion In the diagnosis of cervical lymph node metastasis in patients with PTC, the CEUS quantitative parameters PI and AUC in the margin of cancer nodules have high accuracy and sensitivity, which have important clinical significance.