Value of Ultrasound Elastography in the differential diagnosis of cervical lymph nodes: A comparative study

Elastography has the potential to improve diagnostic accuracy of ultrasound in differentiating benign from malignant lymph nodes of cervical region when used as an adjunct to gray-scale and Doppler USPURPOSE: To search for the usefulness of ultrasound (US) elastography in the evaluation of enlarged cervical lymph nodes in comparison with grayscale and color Doppler US.MATERIALS AND METHODS: From November 2009 to March 2011,220 lymph nodes (malignant, n=67; benign, n=153) of 170 consecutive patients who were referred for sonography of neck were enrolled into this study. The benign group included 2 cases of Kikuchi lymphadenitis, 2 cases of Rosai-Dorfman disease, 2 cases of chronic lymphadenitis, 8 cases of infectious mononucleosis, 8 cases of granulomatous lymphadenitis, 21 cases of tularemia and 110 cases of acute lymphadenitis. In malignant group, there were 40 cases of lymphoma and 27 cases of metastasis (originated from lung adenocarcinoma and squamous cell carcinoma, breast carcinoma, rhabdomyosarcoma, ameloblastic fibrosarcoma, mixed germ cell tumor, invasive urothelial carcinoma, head and neck squamous cell carcinoma).Grayscale US images were evaluated according to following criteria; short-axis diameter, long to short axis ratio, hilum, echogenicity and microcalcification. For color Doppler US five different patterns were defined according to vascularization patterns. Elastographic scores of the lesions were categorized to five main groups according to distribution and percentage of hard area of lymph node. The mean strain index values were calculated for each lymph node. Histopathologic findings, clinical and laboratory data, imaging findings were used as reference standards for the diagnosis of benign and malignant lymph nodes.RESULTS: Sensitivity, specificity and accuracy of grayscale US were 97%, 31.4%, 51.4%, respectively; 76.1%, 82.4%, 80.5%for color Doppler and 82.1%, 56%, 64.1%for US elastography. The strain index was calculated using receiver-operating characteristic curve analysis. When the cut-off value for the differentiation of benign and malignant lymph nodes was accepted as 1.7, sensitivity, specificity and accuracy of the strain index were %71.6, %76, 75%respectively.CONCLUSION: US elastography is a useful additional imaging technique to grayscale and Doppler US in the evaluation of cervical lymphadenopaties