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.