Strain and Shear Wave Elastography in Thyroid Nodules: Tissue Stiffness as a Complementary Risk Marker for Differentiating Benign, Indeterminate, and Malignant Cytology

Abstract

ABSTRACT Objective To evaluate the diagnostic performance of shear wave elastography (SWE) and strain elastography (SE) as complementary techniques to conventional B‐mode ultrasound for differentiating benign, indeterminate, and malignant thyroid nodules. Methods This prospective cross‐sectional study included 208 thyroid nodules evaluated using B‐mode ultrasound, Color Doppler, SWE, and SE. Nodules were classified according to the ACR TI‐RADS and Bethesda systems, and histopathological diagnosis was obtained when surgery was performed. Receiver operating characteristic (ROC) analysis determined the optimal SWE cutoff value and generalized estimating equations (GEE)‐based multivariable logistic regression models were used to identify independent predictors of malignancy. Results SWE demonstrated excellent diagnostic performance for distinguishing Bethesda V/VI from Bethesda II nodules (AUC, 87.6%), with an optimal cutoff value of ≥ 26 kPa (80.0% sensitivity and 81.0% specificity). After multivariable adjustment, hard strain elastography, SWE ≥ 26 kPa, male sex, irregular margins, and predominantly central vascularization independently predicted malignant cytology (Bethesda V/VI vs. Bethesda II). In the comparison with indeterminate cytology (Bethesda III/IV), SWE remained an independent predictor together with male sex, macrocalcifications, microcalcifications, and predominantly central vascularization. Hard strain elastography was the only independent predictor of malignant histopathological diagnosis. Conclusion SWE and SE provide complementary diagnostic information beyond conventional B‐mode ultrasound. SWE demonstrated excellent performance for cytological risk stratification, whereas hard strain elastography was the only independent predictor of malignant histopathological diagnosis. These findings support the complementary use of elastography alongside conventional ultrasound in thyroid nodule risk stratification.