Ultrasound Strain Elastography for Circumscribed Solid Thyroid Nodules without Malignant Features Categorized as Indeterminate by B-Mode Ultrasound

The aim of this study was to evaluate the diagnostic performance of ultrasound strain elastography (USE) for circumscribed solid thyroid nodules without malignant or benign features seen on US. This retrospective study included 197 thyroid nodules in 196 patients who underwent USE with color mapping and strain ratio measurement between 2010 and 2014. Of the 197 nodules, 24 (12.2%) were malignant. No significant differences in color mapping or strain ratio were observed between benign and malignant nodules. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 29.2% (95% confidence interval [CI]: 13.8%-49.4%), 77.5% (95% CI: 75.3%-80.3%), 15.2% (95% CI: 7.2%-25.8%), 88.7% (95% CI: 86.3%-92.0%), and 71.6% (95% CI: 67.8%-76.5%) for color mapping and 50.0% (95% CI: 30.%-69.5%), 57.2% (95% CI: 54.5%-59.9%), 14.0% (95% CI: 8.5%-18.4%), 89.2% (95% CI: 85.0%-93.4%) and 56.3% (95% CI: 51.6%-61.1%) for strain ratio measurement, respectively. USE with color mapping and strain ratio measurement has a limited ability to differentiate benign from malignant nodules for circumscribed solid thyroid nodules without definite malignant features categorized as indeterminate by B-mode US.