Quantitative crawling wave sonoelastography of benign and malignant thyroid nodules

Objective. The purpose of this study is to determine if crawling wave elastography, a novel sonoelastography technique, can be used to provide quantitative measurements of thyroid tissue shear velocity (a measure of tissue stiffness) and distinguish between benign and malignant thyroid nodules. Study Design. Diagnostic test assessment. Setting. Academic university. Subjects and Methods. Fresh thyroid specimens (n = 20) with 44 regions of interest were imaged ex vivo with crawling wave sonoelastography over a 9-month period in 2010 at a single institution. Using the sonoelastography technique, shear velocity estimations and contrast-to-noise ratios were calculated. The higher the shear velocity (SV) and contrastto- noise ratio (CNR), the greater the tissue stiffness. Histological diagnosis was correlated with shear velocity and contrast-to-noise ratio values. Results. Both the shear velocity and contrast-to-noise values of papillary thyroid carcinoma (n = 10, CNR = 5.29, SV = 2.45 m/s) were significantly higher than benign nodules (n = 22, CNR = -0.41, SV = 1.90 m/s). There is a maximum sensitivity and specificity of 100% and 90.9%, respectively, for differentiating papillary thyroid carcinoma from benign nodules using contrast-to-noise ratio values. There is a maximum sensitivity and specificity of 83.3% and 72.7%, respectively, for differentiating papillary thyroid carcinoma from benign nodules using shear velocity values. Insufficient samples were obtained for comparison with other histological types. Conclusion. Crawling wave sonoelastography can provide quantitative estimations of shear velocity, thereby depicting the elastic properties of thyroid nodules. The shear velocity and contrast-to-noise ratio can differentiate between benign thyroid nodules and papillary thyroid carcinoma with high specificity and sensitivity.