Elastography: New Developments in Ultrasound for Predicting Malignancy in Thyroid Nodules

Abstract

BACKGROUND: Elastography is a newly developed dynamic technique that uses ultrasound (US) to provide an estimation of tissue stiffness by measuring the degree of distortion under the application of an external force. US elastography has been applied to differentiate malignant from benign lesions. PATIENTS: This study included 92 consecutive patients with a single thyroid nodule who underwent surgery for compressive symptoms or suspicion of malignancy on fine needle aspiration cytology. Tissue stiffness on US elastography was scored from one (greatest elastic strain) to five (no strain). RESULTS: On US elastography: scores 1 and 2 were found in 49 cases, all benign lesions; score 3 in 13 cases, one carcinoma and 12 benign lesions; and scores 4 and 5 in 30 cases, all carcinomas. Thus, the elasticity scores 4-5 were highly predictive of malignancy (P < 0.0001), with a sensitivity of 97%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 98%. In 32 patients with an indeterminate fine needle aspiration result, the conventional US was not predictive of malignancy, while an US elastographic score of 4-5 was observed in six of seven (86%) patients with carcinoma on histology, and a score of 1-3 in all 25 patients with benign lesions. CONCLUSIONS: US elastography has great potential as an adjunctive tool for the diagnosis of thyroid cancer, especially in indeterminate nodules on cytology. Larger prospective studies are needed to confirm these results and establish the diagnostic accuracy of this new technique.