Ultrasound elastography using carotid artery pulsation in the differential diagnosis of sonographically indeterminate thyroid nodules

Abstract

OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of gray-scale ultrasound and a new method of thyroid ultrasound elastography using carotid artery pulsation in the differential diagnosis of sonographically indeterminate thyroid nodules. MATERIALS AND METHODS. A total of 102 thyroid nodules with indeterminate gray-scale ultrasound features from 102 patients (20 males and 82 females; age range, 16–74 years; mean age, 51 years) were included. The gray-scale ultrasound images of each nodule were reviewed and assigned a score from 1 (low) to 5 (high) according to the possibility of malignancy. Ultrasound elastography was performed using carotid pulsation as the compression source. The elasticity contrast index (ECI), which quantifies local strain contrast within a nodule, was automatically calculated. The radiologist reassessed the scores after concurrently reviewing gray-scale ultrasound and elastography. ROC curve analysis was used to evaluate the diagnostic performances of each dataset and to compare the AUC (Az) values of grayscale ultrasound score alone, ECI alone, and a combined assessment. RESULTS. Significantly more malignant thyroid nodules were hypoechoic than benign nodules (p = 0.014). The ECI was significantly higher in malignant nodules than in benign thyroid nodules. The Az values of each dataset were 0.755 (95% CI, 0.660–0.835) for gray-scale ultrasound score, 0.835 (0.748–0.901) for ECI, and 0.853 (0.769–0.915) for a combined assessment. The Az value for a combined assessment of the gray-scale ultrasound score and the ECI was significantly higher than that for the gray-scale ultrasound score alone (p = 0.022). CONCLUSION. Combined assessment with gray-scale ultrasound and elastography using carotid artery pulsation is helpful for characterizing sonographically indeterminate thyroid nodules as benign or malignant.