Comparison of color-Doppler and qualitative and quantitative strain-elastography for differentiation of thyroid nodules in daily practice.

OBJECTIVE: Strain-elastography provides a new ultrasound-based method that can offer information about the stiffness of thyroid nodules as an indicator of malignancy. The aim of our study was to compare the utility of color-Doppler and strain-elastography in differentiating between benign and malignant nodules.

DESIGN AND METHODS: 77 thyroid nodules (70 benign and 7 malignant) from 70 unselected patients (48 female/22 male, mean age 49.7±14.3 years) were evaluated with color-Doppler and elastography based on a five-scale elastogram score for qualitative elastography and strain ratio for quantitative elastography. As reference tissue we chose normal thyroid tissue [strain ratio a (SR a)] and cervical muscles [strain ratio b (SR b)]. The cytological or histological results were used as a reference standard. Diagnostic performances of qualitative and quantitative elastography were compared using ROC curves.

RESULTS: Vascularization score 3 or 4 was associated with malignancy (p=0.024) as well as elastogram score 4 or 5 (p=0.070, n.s.s.). SR a was indicatively higher and SR b lower in the group of malignant nodules (p=0.065 and p=0.246, n.s.s.). The best cut-off points predicting malignancy were 3.32 for SR a (66.7% sensitivity, 83.3% specificity) and 0.10 for SR b (71.4% sensitivity, 67.1% specificity).

CONCLUSION: In our study, the accuracy of elastography did not surpass other sonographic parameters in differentiating thyroid nodules. The technique can play a role as a supplementary parameter in assessment of malignancy to improve diagnostic efficacy. The best parameter is SR a, but SR b can serve as an alternative if SR a is not assessable.