Conventional US, US Elasticity Imaging, and Acoustic Radiation Force Impulse Imaging for Prediction of Malignancy in Thyroid Nodules

Abstract

To evaluate conventional ultrasonography (US), US elasticity imaging (EI), and acoustic radiation force impulse (ARFI) imaging in thyroid nodule malignancy prediction. This prospective study was institutional review board approved; informed consent was obtained. Study included 375 patients (mean age, 51 years; range, 18-75 years) with 441 pathologically proven thyroid nodules. In 281 women (mean age, 50 years; range, 18-75 years) and 94 men (mean age, 53 years; range, 18-74 years), conventional US, EI, Virtual Touch tissue imaging (VTi; Siemens, Mountain View, Calif), and Virtual Touch tissue quantification (VTq; Siemens) of ARFI imaging were performed for each nodule. Multivariate logistic regression analysis was performed to assess 17 independent variables for malignancy prediction. Diagnostic performance was evaluated with receiver operating characteristic (ROC) curve analysis. There were 325 benign and 116 malignant nodules. Marked hypoechogenicity (odds ratio [OR]: 83.88; 95% confidence interval [CI]: 17.81, 394.99) was the strongest independent predictor for thyroid malignancy, followed by shape taller than wide (OR: 8.69; 95% CI: 2.87, 26.31), VTi (OR: 6.54; 95% CI: 3.61, 11.88), moderate hypoechogenicity (OR: 3.98; 95% CI: 1.13, 14.05), poorly defined margin (OR: 3.27; 95% CI: 1.22, 8.77), female sex (OR: 2.55; 95% CI: 1.33, 4.91), coarse background of surrounding thyroid tissue (OR: 2.01; 95% CI: 1.12, 3.62), and VTq (OR: 1.78; 95% CI: 1.28, 2.47) (all P < .05). EI was not significantly associated with thyroid malignancy (P = .855). Area under the ROC curve (Az) for VTq and VTi was higher than that with other significant independent variables. Az, sensitivity, and specificity were 0.91 (95% CI: 0.87, 0.94) and 0.86 (95% CI: 0.82, 0.90), 80% and 71.6%, and 93.8% and 83.4%, respectively, for VTi and VTq. VTq of at least 2.87 m/sec and VTi of at least grade IV were the best cutoff values for malignant thyroid nodules. ARFI imaging is promising for malignant thyroid nodule prediction, with higher diagnostic performance than conventional US or EI. ARFI can be used to supplement conventional US to diagnose thyroid nodules in patients referred for surgery.