Measurement of shear wave velocities coupled with an evaluation of elasticity using ARFI elastography in diagnosis of papillary thyroid carcinoma

Abstract

This study aimed to evaluate the diagnostic value of measuring the shear wave velocities (Vs) of thyroid nodules in diagnosis of the thyroid carcinoma. Using Virtual Touch Tissue Quantification (VTTQ) of acoustic radiation force impulse (ARFI) elastography (ACUSON S2000®, Siemens Medical Solutions, Mountain View, CA, USA), we measured the Vs of thyroid nodules in 39 nodules from 34 patients (four males and 30 females) before surgery. Elasticity itself was also estimated by VTTI (Virtual Touch Tissue Imaging) using ARFI. The average Vs of normal thyroid tissue was 2.24 ± 0.68 m/s. Twenty-three out of 39 nodules showed an average 2.52 ± 1.33 m/s. However, 16 other nodules showed “X.XX m/s”. These 16 nodules showed either “black” or “honeycomb” patterns of elasticity in VTTI. This value suggested that the Vs of these nodules were too fast or heterogenous to measure by this device. After the surgery, the pathologies of these nodules were revealed to be papillary carcinoma (21 cases), adenomatous goiter (11), follicular carcinoma (4), follicular adenoma (2) and follicular lymphoma (1). Five papillary carcinomas were found within adenomatous goiters. Nodules from four follicular carcinomas showed average Vs of 1.92 ± 0.48 m/s, while two follicular adenomas and follicular lymphoma showed 2.19 ± 0.06 and 2.34 m/s respectively. Nodules of adenomatous goiter showed 2.14 ± 0.60 m/s. On the other hand, nodules from five out of 21 papillary carcinomas showed average Vs of 4.00 ± 2.37 m/s. In the nodules of 16 papillary carcinomas, Vs were measured as “X.XX m/s” and this value was only observed in nodules of papillary carcinoma. These data reflected high and/or heterogenous elasticity of papillary carcinoma, in other words, the tissue of papillary carcinoma was hard and/or heterogenous. It was notable that the Vs value of “X.XX m/s” strongly suggested papillary carcinoma.