The Role Of Contrast-Enhanced Ultrasound In The Diagnosis Of Cervical Lymph Node Metastasis

Objective:To investigate the diagnostic value of contrast-enhanced ultrasound(CEUS)in differentiating metastatic cervical lymph nodes from benign nodes in patients with cancer and the key CEUS indicators for metastatic lymph nodes.Methods:Totally 91 cervical lymph nodes from 89 cancer patients were evaluated by conventional ultrasound(US)and CEUS before core needle biopsy(CNB)or fine needle aspiration(FNA)in the Second Affiliated Hospital of Zhejiang University School of Medicine from January 2017 to June 2018.CNB pathology or FNA cytology combined with more than 6 months' follow-up result was regarded as the 'gold standard'.Qualitative and quantitative analysis of CEUS were made in metastasis group and non-metastasis group.Qualitative indexes included pattern,overall intensity,heterogeneity of enhancement and appearance of perfusion defect.Quantitative indexes included peak intensity(Peak),time to peak(TTP),the sharpness of the curve(Sharpness),area under the curve(AUC)and standard deviation(StdDev)of the peak intensity in region of interest(ROI),which showed the heterogeneity degree of intensity in ROI.Results:48 metastatic cervical lymph nodes and 43 benign lymph nodes were analyzed.Metastatic lymph nodes more often manifested centripetal perfusion(P<0.001)?,heterogeneous enhancement(P=0.001),perfusion defects(P=0.001)than benign lymph nodes on CEUS,while the overall intensity between the two groups was not significantly different(P>0.05).The sensitivity of these three signs were 0.479?0.604?0.396,respectively,and the specificity were 0.927?0.767?0.907,respectively.And inter-observer consistency test showed that the Kappa value of above-mentioned features were 0.515?0.643?0.693,respectively.Quantitative analysis showed that only StdDev was different between two groups(4.92± 1.89 versus 6.45 ± 1.96,P<0.001),further manifesting the diagnostic value of heterogeneous enhancement to lymph node metastasis.The combination of CEUS and US can improve the accuracy of diagnosis of metastatic cervical lymph node,with the sensitivity of 0.938(versus 0.813 or 0.729),the specificity of 0.721(versus 0.605 or 0.791),and the accuracy of 0.835(versus 0.714 or 0.758).Conclusion:CEUS is a promising tool combined with conventional US for diagnosis of metastatic cervical lymph nodes in cancer patients.Centripetal perfusion pattern,heterogeneous enhancement and perfusion defect are significant indicators of cervical lymph node metastasis.However inter-agreement for centripetal perfusion pattern was only moderate between different readers.The qualitative indicators may be better than the quantitative indicators for predicting the metastasis of lymph node,and the latter method need to be further investigated.