Using Ultrasound Elastography for Making the Differential Diagnosis of Thyroid Nodules / 대한내분비외과학회지

ABSTRACT

PURPOSE: Ultrasound (US) elastography is a newly developed imaging technique for assessing tissue stiffness by measuring the degree of the tissue's deformation in response to the application of an external force. This technique has recently been applied for making the diagnosis of nodular thyroid disease. The purpose of this study was to evaluate the diagnostic utility of US elastography for differentiating benign thyroid nodules from malignant thyroid nodules. METHODS: A total of 63 consecutive patients with thyroid nodules and who were referred for surgical treatment were examined in this study. Seventy-five nodules in these patients were examined by US B-mode, color Doppler US and US elastography. The final diagnosis was obtained from the histologic findings. The tissue stiffness on ultrasound elastography was scored from 1 (elasticity in the whole nodule) to 5 (no elasticity in the nodule and in the posterior shadowing). RESULTS: On US elastography, 18 of 32 benign nodules (56.3%) had a score of 1 to 3, whereas 23 of 43 malignant nodules (62.8%) had a score of 4 to 5. With applying a US elastography score of 4-5 as an indicator for malignancy, the sensitivity, specificity, positive predictive value and negative predictive value of US elastography were 65.9%, 52.9%, 62.8% and 56.3%, respectively. Of the 14 follicular tumors, 12 were follicular adenoma and four were follicular carcinoma. The sensitivity and specificity of US elastography for diagnosing follicular carcinoma were 50.0% and 81% (56=69), respectively. The positive and negative predictive values were 55.2% (16=29) and 60.0%, respectively. The accuracy of the technique was 57.1%. The findings of US elastography were not significantly correlated with the histopathologic findings. CONCLUSION: This study has shown that US elastography may be not useful for differentiating between benign and malignant thyroid nodules. Further studies are needed to confirm the usefulness of US elastography for making the differential diagnosis of thyroid nodules.