The technique of elastography was introduced into the clinic for the purpose of improving the diagnostic performance of thyroid carcinoma. Due to its a noninvasive nature and later on with additional imaging modality features, Ophir et al. [44] proposed elastography in 1991 for the purpose of evaluating the stiffness of tissue and it has been widely used ever since. Many studies have indicated that adding elastographic technique to conventional US can help to improve the differentiation of thyroid lesions [45, 46]. Elastography is based upon the mechanical principles that tissue displacement is more in softer tissue than in harder tissue; hence elastography can be used to estimate the tissue stiffness in way that can reflect the nature of lesions. Various studies have indicated that the increased in tissue hardness is mostly associated with a raising risk of malignancy [47]. …show more content…
Initial evaluations of these two techniques in clinical trials have indicated that they may improve the diagnostic performances of differentiating benign from malignant lesions and help to reduce the number of unnecessary benign thyroid biopsies [15, 16]. Strain elastography is a previous elastography technique; however, it requires manual compression by the operator and can only provide semi-quantitative images [17]. The second type of elastography is shear-wave elastography (SWE). SWE is the latest elastographic technique with more reproducible and less operator-dependent and doesn’t rely much on external force. SWE can measure quantitative elastographic values which can be expressed in either kPa or m/s [18 -