The role of sonoelastography in acute, subacute and chronic thyroiditis: a novel application of the method.

OBJECTIVE: Reports on sonoelastography, which provide an objective estimation of tissue elasticity, are scarce in terms of thyroiditis. The aim of this study was to prospectively assess the applicability of sonoelastography in different types of thyroiditis. DESIGN: The study assessed and compared the thyroid tissue stiffness in patients with acute thyroiditis (AT), subacute thyroiditis (SAT), and chronic autoimmune thyroiditis (CAT) with healthy control subjects (CS), followed up for 10 weeks. METHODS: The study group consisted of two patients with AT, 18 patients with SAT, 18 patients with CAT, and 40 CS matched for age and gender. Sonoelastography was performed at baseline, at a 4-week follow-up during treatment, and at 10 weeks following diagnosis and treatment initiation. RESULTS: Thyroid tissue stiffness was higher in SAT at baseline (214.26 ± 32.5 kPa) in comparison with values recorded at a 4-week follow-up (45.92 ± 17.4 kPa) and at 10 weeks following diagnosis and treatment initiation (21.65 ± 5.3 kPa, P < 0.0001). Baseline thyroid stiffness in SAT was higher than that found in CAT (36.15 ± 18.7 kPa, P < 0.0001) and CS (16.18 ± 5.4 kPa, P < 0.0001). In the remission of SAT, thyroid stiffness was lower than that found in CAT (P = 0.006), while it was higher than that in CS (P = 0.0008). No difference was observed between thyroid stiffness in SAT at 4-week follow-up and in CAT. Patients with CAT presented higher thyroid stiffness than CS (P < 0.0001), which was not influenced by L-thyroxine treatment. Thyroid stiffness in patients with AT was 216.6 and 241.9 kPa at baseline; after treatment, it decreased to 17.93 and 85.348 kPa respectively. CONCLUSIONS: Sonoelastography may assist in the diagnosis and treatment monitoring of AT, SAT and CAT, as well as in the differentiation of the various types of thyroiditis.