Thyroid stiffness assessment by acoustic radiation force impulse elastography (ARFI)

To evaluate and compare the values of thyroid tissue elasticity in subjects without known thyroid pathology, in patients with Graves' disease and with chronic autoimmune thyroiditis (CAT).

We performed a prospective study that included 74 subjects, 23 without thyroid pathology, 29 with Graves' disease and 22 with CAT (diagnosed by specific tests). In all patients, 10 elastographic measurements were performed in the right thyroid lobe (RTL) and 10 in the left thyroid lobe (LTL) using a 2-6 MHz convex probe. Median values were calculated for each thyroid lobe, measured in meters/second (m/sec). We calculated a mean ARFI value from measurements made in the RTL and LTL.

Thyroid stiffness was statistically significant lower in normal subjects vs. those with Graves' disease (2.07±0.44 m/sec vs. 2.82±0.47 m/sec, p<0.001) and with CAT (2.07±0.44 m/sec vs. 2.49±0.48 m/sec, p=0.004). We also found a statistically significant difference between subjects without thyroid pathology and those with autoimmune thyroid pathology (Graves' disease and CAT) (2.07±0.44 m/sec vs. 2.68±0.50 m/sec, p<0.001).

ARFI seems to be a useful method for the evaluation of diffuse thyroid gland pathology and is able to predict with sufficient accuracy the presence of thyroid diffuse diseases (AUROC=0.80).