Diagnostic role of conventional ultrasonography and shearwave elastography in asymptomatic patients with diffuse thyroid disease: initial experience with 57 patients

Abstract

Purpose: Thyroid ultrasonography (US) is a useful diagnostic tool in the evaluation of diffuse thyroid disease (DTD), whereas shearwave elastography is a dynamic technique that can provide information about tissue hardness by using acoustic shearwaves remotely induced by a focused ultrasonic beam. This study aims at investigating the role of conventional US and shearwave elastography in the diagnosis of asymptomatic patients with DTD.

Materials and methods: Fifty-seven patients who underwent both conventional US and shearwave elastography were included in this study. Interobserver variability of the three radiologists in assessment of underlying thyroid echogenicity on conventional US was analyzed. Diagnostic performances for diagnosing DTD on conventional US and shearwave elastography were calculated and compared.

Results: Fair agreement was observed in the identification of DTD with conventional US (kappa value= 0.27). The area under the receiver operating characteristic curve (Az) were 0.52-0.585 on conventional US by three radiologists. The Az values when using the mean and maximum elasticity values as a diagnostic criteria for DTD were 0.619 and 0.59 on shearwave elastography. Patients with DTD showed higher mean [24.1±10 kilo-Pascals (kPa)] and maximum (36.4±13.3 kPa) elasticity values on shearwave elastography when compared to the normal group (23.4±10.8 kPa and 33.7±12.4 kPa, respectively), although without statistical significance (p=0.802 and p=0.452, respectively).

Conclusion: Conventional US did not show reliable interobserver agreement in the diagnosis of DTD. Although not statistically significant, shearwave elastography may provide additional information in the diagnosis of DTD. Therefore, larger prospective studies are needed to define the values of shearwave elastography for diagnosing DTD.

Keywords: Ultrasonography; diffuse thyroid disease; shearwave elastography; thyroid gland.

Fig. 1

Conventional ultrasound and shearwave elastography images from a 61-year-old woman with normal thyroid function. (A and B) Transverse and longitudinal ultrasound images show normal homogeneous thyroid parenchymal echogenicity. (C) A shearwave elastography image of underlying thyroid parenchyma shows mean and maximum elasticity values of 16.2 kPa and 25.8 kPa.

Fig. 2

Conventional ultrasound and shearwave elastography images from a 29-year-old woman with Hashimoto thyroiditis. (A and B) Transverse and longitudinal ultrasound images show heterogeneous and hypoechoic underlying thyroid parenchyma. (C) A shearwave elastography image shows mean and maximum elasticity of 15.8 kPa and 31.6 kPa.

Fig. 3

Box plots show elasticity values of normal and diffuse thyroid disease group. The central line of each box indicates the median and the asterisk (^*) indicates the mean elasticity value of each group, respectively. In the box plots of mean elasticity values (A) and maximum elasticity values (B), mean values of both mean and maximum elasticity were higher in patients with diffuse thyroid disease than those in the normal group. However, there were no statistically significant differences between the two groups (p=0.802 and p=0.452). DTD, diffuse thyroid disease; Mean, mean elasticity value; Maximum, maximum elasticity value.