Assessment by real-time shear wave elastography (SWE) in diffuse thyroid pathology: utility of this new technique

Real-time shear wave ultrasound elastography (SWE) is a new technique, recently introduced in the evaluation of thyroid pathology.

Purpose: To evaluate and compare the values of the elasticity index (EI) measured by SWE in healthy subjects and in cases with diffuse thyroid pathology, in order to establish if this investigation could be useful, as a diagnostic tool, in these thyroid diseases.

Patients and methods: We studied 136 subjects (F/M = 113/23), 49 with chronic autoimmune thyroiditis (CAT), 35 with Graves' disease (GD) diagnosed by specific tests and 52 healthy volunteers. For all subjects, 3 elastography determinations were performed for each thyroid lobe and a mean value was calculated and expressed in kilopascals (kPa). The measurements were performed with an Aixplorer system (Supersonic Image Inc. France), using a linear high-resolution transducer 15 – 4 MHz.

Results: Three valid SWE measurements were obtained in both thyroid lobes in all the subjects. The mean EI (kPa) was similar in the right and left thyroid lobe in patients with CAT, GD and in normal subjects: 27.06 ± 11.31 vs. 25.05 ± 10.82, p = 0.37, 23.55 ± 10.3 vs. 22.84 ± 11.34, p = 0.78 and 19.6 ± 6.55 vs. 19.48 ± 6.84, p = 0.93, respectively. Because the mean SWE values obtained in the right and in the left lobe were similar in subjects from both groups we decided to use the EI from the right lobe for comparison. The mean EI assessed by SWE in patients with CAT and GD was significantly higher than in normal subjects: 27.06 ± 11.31 kPa vs19.6 ± 6.55 kPa, p < 0.0001 and 23.55 ± 10.3 vs19.6 ± 6.55 kPa, p = 0.03, respectively. The mean EI in patients with CAT and GD did not differ significantly (p = 0.15).

Conclusion: SWE seems to be an useful method to differentiate between subjects with normal thyroid and those with autoimmune thyroid diseases, but cannot help in distinguishing between CAT and GD.