Thyroid nodule parameters influencing performance of ultrasound elastography using intrinsic compression.

The influence of nodule parameters on the diagnostic accuracy of ultrasound (US) elastography in differentiating thyroid nodules was evaluated. One hundred seventy-six nodules (83 benign, 93 malignant) from 156 patients were included. Conventional B-mode and elastography examinations were performed. External compression with a transducer was not applied, as the pulsation from the carotid artery was used. Three nodule parameters (size, depth and distance to the carotid artery) were measured. The elasticity contrast index, in which increases with the stiffness of the nodules, was correlated with distance to the carotid artery (correlation coefficient = 0.283 in all nodules and 0.415 in malignant nodules, p < 0.01 in both groups). The diagnostic accuracy of elastography was significantly associated with a nodule's distance to the carotid artery (p < 0.05). No significant correlation was found between the diagnostic accuracy of elastography and the other parameters. Elastography results for nodules close to the carotid artery should be interpreted with caution.