Comparison of Conventional Ultrasound, Doppler, Elastography and Contrast Enhanced Ultrasonography Parameters with Histopathology Findings in the Differential Diagnosis of Benign and Malignant Thyroid Nodules

Background: Though neck ultrasound is the first line of choice for the screening of thyroid nodules, very few studies have compared the diagnostic performances of both conventional and advanced ultrasound parameters. In this study, we aim to compare various conventional and advanced ultrasound imaging parameters and confirm it with histopathology findings to differentiate between benign and malignant thyroid nodules. Methods: One hundred and thirty nine patients with 173 thyroid nodules underwent conventional ultrasonography (cUSG) which included gray-scale parameters, colour Doppler (CD) and power Doppler (PD) followed by elastography and contrast enhanced ultrasonography (CEUSG). Post-USG imaging all patients underwent fine needle aspiration cytology followed by surgery if indicated and histopathological results were obtained. Stata 11.2 statistical software was used for the statistical analysis. Results: Of 173 nodules, 65 were benign and 108 were malignant. cUSG had a sensitivity, specificity, PPV, NPV and accuracy of 94.4%, 90.4%, 94.4%, 90.4%, and 91.9%, respectively with AUC:0.97. On ROC analysis, the cut-off value for differentiating malignant from benign thyroid nodules on Ueno elasticity scoring was >3; AUC: 0.86 versus >2.2 using elasticity ratio method, AUC: 0.90. CEUSG and elastography had sensitivity, specificity, PPV, NPV and accuracy of 93.8%, 95.3%, 97.2%, 89.8%, and 94.2%, respectively with AUC:0.98. On combining and ranking, both conventional and advanced cUSG parameters, the significant indicators for malignancy were heterogeneous contrast enhancement, followed by Type-IV/V PD flow patterns, absence of ring enhancement and elasticity ratio >2.2 patterns with the largest AUC:0.994. Conclusions: Conjoint analysis of specific features of thyroid nodules on cUSG, elastography and CEUSG will enhance the diagnostic value in the screening of thyroid nodules.