| Objective(s):1.To investigate the high-frequency ultrasound features of metastatic lymph nodes in the lateral cervical regions of patients with PTC.2.To help identify benign lymph nodes and metastatic lymph nodes in the lateral cervical regions of patients with PTC by high-frequency Contrast-enhanced ultrasound and quantitative analysis of Contrast-enhanced ultrasound.Methods:Inclusive criteria:①Thyroidectomy and lateral cervical lymph node dissection were performed.The operation data were detailed and PTC was confirmed by postoperative pathology.②Pre-operative high-frequency ultrasound and CEUS imaging data were complete.Exclusion criteria:①The thyroid was normal,and the malignant lymph nodes was from primary disease of lymph nodes or other parts of the body except thyroid metastasis to the neck.②Patients with previous history of cervical radiofrequency or microwave ablation.1.Gray-scale ultrasound:the high-frequency probe was adjusted to 8～12MHz.According to AJCC’s cervical lymph node partition method,the lateral cervical lymph nodes were scanned from the submandibular space along the internal jugular vein to supraclavicle in order to pay attention to the important anatomical marks of the lateral cervical lymph nodes.The length diameter ratio of lymph nodes,absent echogenic hilus or not,nodal echogenicity,mass hyperecho,microcalcification and cystic degeneration were recorded and compared between the two groups.2.Color Doppler:adopt low-speed flow condition mode,appropriately adjust the color blood flow gain to avoid noise,and adjust the scale to 3～9 cm/s.According to Adler classification,the blood flow was divided into 0～3 grades.According to the blood flow distribution,it was divided into no blood flow,central distribution,peripheral distribution and mixed distribution.Adler grade and blood flow type of the two groups were recorded and compared.3.Contrast-enhanced ultrasound:high-frequency ultrasound showed suspicious lymph nodes in longitudinal plane,adjusted to Color Doppler conditions,select the section with the vascularity.Set the ultrasound machines to contrast mode and adjust the corresponding parameters.Confected SonoVue microbubble contrast agent.Two point four milliliter of contrast agent was injected through the median cubital vein,and the tube was flushed with 5 ml normal saline within 3s.After the bolus injection,the timer was turned on,and the dynamic image about 2 minutes was observed and stored.The perfusion pattern,perfusion uniformity and perfusion defect were recorded and compared between the two groups.4.Quantitative analysis of Contrast-enhanced ultrasound:Siemens Helx S3000 built-in quantitative analysis software was used for analysis.The areas of interest of the same size_were selected in the central area and peripheral area of the target lymph nodes.The corresponding TIC was obtained,and the quantitative parameters were recorded include PI,TTP,AUC and MTT.The corresponding parameters of central and peripheral area were compared between the two groups.The trend of TIC was compared between the two groups.Results:The clinical data of 39 patients with lateral cervical lymph node metastasis from PTC admitted to Department of thyroid and breast surgery,the Second Affiliated Hospital of Kunming Medical University from November 2018 to December 2020 were collected.Pre-operative ultrasonographic data of 64 lymph nodes were obtained.Post-operative pathology confirmed that 42 lymph nodes were PTC metastatic,and 22 lymph nodes were not PTC metastatic.Benign lymph nodes(n=22)and malignant lymph nodes(n=42)were included.1.Pre-operative high-frequency ultrasound has high temporal and spatial resolution,which can improve the diagnosis of lateral cervical lymph nodes.The distribution of metastatic lymph nodes in the lateral cervical regions was in the order of level Ⅳ,level Ⅲ and level Ⅱ.2.There were significant differences between benign and malignant lymph nodes in the present or absence of echogenic hilus,mass hyperecho and microcalcification(P<0.05).There was no significant difference between benign and malignant lymph nodes in the long axis and short axis ratio,nodal echogenicity and cystic degeneration(P>0.05).Compared with benign lymph nodes,malignant lymph nodes often show absence of echogenic hilus,mass hyperecho and microcalcifications are present.3.There were significant differences in blood flow type and Adler grade between benign and malignant lymph nodes(P<0.05).Compared with benign lymph nodes,the color flow distribution of malignant lymph nodes often show mixed blood flow and peripheral flow,the blood flow grade is higher which means more vascularity.4.There were significant differences in enhancement pattern,enhancement uniformity and enhancement defect between benign and malignant lymph nodes(P<0.05).Compared with benign lymph nodes,the performance of real-time Contrast-enhanced ultrasound in malignant lymph nodes often show centripetal enhancement,uneven enhancement and enhancement defect.5.In the quantitative analysis of Contrast-enhanced ultrasound,PI and AUC of benign lymph nodes central areas were significantly higher than those of peripheral areas;there was no significant difference in TTP and MTT between benign lymph nodes central areas and peripheral areas(P>0.05).PI in the peripheral areas of malignant lymph nodes were significantly higher than those in the central areas.There was no significant difference in TTP,AUC and MTT between central and peripheral areas of malignant lymph nodes(P>0.05).6.In the quantitative analysis of Contrast-enhanced ultrasound,the PI of benign lymph nodes central areas were significantly higher than those of malignant lymph nodes.The cut-off value of PI was 21.55%,AUC was 0.677,sensitivity was 85.7%,specificity was 56.1%.There was no significant difference in TTP,AUC and MTT of central areas between benign and malignant lymph nodes(P>0.05).There was no significant difference in PI,TTP,AUC and MTT of peripheral area between benign and malignant lymph nodes(P>0.05).7.Gray-scale ultrasound,Color Doppler combined with Contrast-enhanced ultrasound can improve the diagnostic accuracy of lateral cervical lymph nodes.Conclusion(s):Pre-operative high-frequency ultrasound is more effective in locating metastatic lymph nodes in the lateral cervical regions of PTC patients.Compared with benign lymph nodes,metastatic lymph nodes are characterized by absence of echogenic hilus,exist mass hyperecho and microcalcification,mixed and peripheral flow,and more vascularity.Compared with benign lymph nodes,metastatic lymph nodes showed centripetal enhancement,uneven enhancement and enhancement defect.In contrast quantitative analysis,PI and AUC in the central areas of benign lymph nodes were significantly higher than those in the peripheral areas;PI in the peripheral areas of metastatic lymph nodes were significantly higher than those in the central areas.PI in the central areas of benign lymph nodes were significantly higher than those of metastatic lymph nodes.Pre-operative high-frequency ultrasound combined with high-frequency Contrast-enhanced ultrasound can improve the diagnostic accuracy of metastatic lymph nodes in the lateral cervical regions of PTC patients. |
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