Objective:To analyze the diagnostic performance of contrast-enhanced ultrasound (CEUS) in the diagnosis of papillary thyroid carcinoma (PTC) and related parameters in the diagnosis of cervical lymph node metastasis.Methods:The clinical data of 130 patients who underwent ultrasonography in Ningbo Hospital of Traditional Chinese Medicine from Jan. 2019 to Jan. 2022 were retrospectively analyzed. All patients received contrast-enhanced ultrasonography and postoperative pathological examination. According to the pathological diagnosis of benign and malignant tumors, they were divided into PTC group and benign nodule group. In the PTC group, there were 46 males and 40 females, aging 51.79±5.01 years old, ranging from 32 to 63 years old; In the nodule group, there were 25 males and 19 females, aging 52.05±4.89 years old, ranging from 33 to 64 years old. According to the presence or absence of cervical LNM, they were divided into a metastasis group of 31 cases, 17 males and 14 females; age (51.69±6.14 years), ranging from 36 to 63 years; 55 cases in the non-transfer group, 29 males and 26 females, aging (51.75±6.18) years, ranging from 36 to 62 years. Comparative analysis of different nodule properties, presence or absence of LNM, different lesion diameters in imaging manifestations and time-intensity curve (time-intensity curve, TIC) parameters differences, measurement data between groups were conducted by independent sample t test, count data between groups were compared by χ2. The receiver operating characteristic curve (receiver operating characteristic, ROC) was drawn to evaluate the diagnostic performance of TIC parameters for cervical LNM. Results:The proportion of PTC nodules with low enhancement, irregular enhancement, heterogeneous enhancement, unclear lesion boundary, and perfusion defect (72.09%, 87.21%, 88.64%, 69.77%, 70.93%) was significantly higher than that of benign nodules (38.64%, 11.36%) %, 27.27%, 77.27%, 27.27%) ( χ2=13.67, 70.75, 49.69, 25.92, 18.24, P<0.05) ; PTC nodule peak intensity (peak intensity, PI), TIC area under the curve (area under curve, AUC) was significantly lower than that of benign nodules (14.86±2.11dB vs 23.94±3.51dB, 985.14±105.31dB·s vs 1621.14±182.61dB·s) ; time to peak (TTP) was significantly higher than that of benign nodules ( 44.82±5.01s vs 36.95±4.18s) ( t=18.39, 21.36, 8.94, P<0.05) ; there was no significant difference in mean transit time (MTT) ( P>0.05) ; AUC was significantly higher than that of the non-metastatic group (16.86±2.09) dB vs (13.73±1.42) dB, (1163.54±131.41) dB·s vs (884.59±93.25) dB·s ( t=8.25, 11.46, P<0.05) ; The PI and AUC of PTC patients with lesion diameter ≤1.5 cm were significantly lower than those of patients with lesion diameter > 1.5 cm (11.56±1.94) dB vs (15.93±2.46) dB, (876.97±100.21) dB·s vs (1020.09±125.41) dB·s ( t=8.39, 5.34, P< 0.05), there was no significant difference in terms of TTP or MTT ( P>0.05) ; the AUC of PI in the diagnosis of cervical lymph node metastasis in PTC patients was 0.888 (95% CI: 0.807-0.969), the sensitivity was 90.91%, and the specificity was 77.42%; The AUC for the diagnosis of cervical lymph node metastasis in PTC patients was 0.972 (95% CI: 0.943-1.000), with a sensitivity of 87.10% and a specificity of 96.36%. Conclusion:The CEUS manifestations of PTC nodules are mostly irregular and heterogeneous low-enhancement, and the TIC-related parameters of PTC nodules and benign nodules are significantly different, and TIC-related parameters have good diagnostic efficiency for patients with cervical lymph node metastasis.