Real-Time Ultrasound Elastography in the Diagnosis and Differential Diagnosis of Subacute Thyroiditis

Purpose: To assess the value of real-time sonographic (US) elastography in the diagnosis of subacute thyroiditis (SAT). Methods: This study included 29 lesions from 20 patients with SAT, 33 nodules from 24 patients with multinodular goiter, and 27 nodules from 23 patients with thyroid cancer. Eighty-nine lesions in these patients were examined by grayscale US and real-time US elastography. An elasticity score (ES), based on four classes of tissue stiffness (class 1 for soft lesions; class 2 and 3 for lesions intermediate in stiffness; class 4 for inelastic lesions), was introduced. The distribution of ESs for SAT and multinodular goiter or thyroid cancer was compared. Also, the correlation between serum-free thyroxine (FT4) concentrations and ESs for lesions in patients with SAT was analyzed. Results: Nineteen of 29 SAT lesions had an ES of 3; the rest had an ES of 4. Of 33 multinodular goiter nodules, 5 had an ES of 1, 23 had an ES of 2, and 5 had an ES of 3. Eleven of 27 malignant thyroid nodules had an ES of 3; 15 had an ES of 4, and 1 had an ES of 2. In the distribution of ESs, there was a statistically significant difference between SAT lesions and multinodular goiter nodules (p < 0.05), but there was no significant difference between SAT lesions and malignant nodules (p > 0.05). No correlation existed between serum FT4 concentrations and ESs for the lesions in patients with SAT (p > 0.05). Conclusions: Real-time US elastography does not provide conclusive information in the diagnosis and differential diagnosis of SAT due to its inability to distinguish between SAT and thyroid cancer. (C) 2011 Wiley Periodicals, Inc. J Clin Ultrasound 39: 435-440, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jcu.20850