Strain US Elastography for the Characterization of Thyroid Nodules: Advantages and Limitation

Abstract

Thyroid nodules, with their high prevalence in the general population, represent a diagnostic challenge for clinicians. Ultrasound (US), although absolutely reliable in detecting thyroid nodules, is still not accurate enough to differentiate them into benign and malignant. A promising novel modality, US elastography, has been introduced in order to further increase US accuracy. The purpose of this review article is to assess the thyroid application of US strain elastography, also known as real-time elastography or quasistatic elastography. We provide a presentation of the technique, and of up-to-date literature, analyzing the most prominent results reported for thyroid nodules differentiation. The practical advantages and limitations of strain elastography are extensively discussed herein.

Figure 1

Benign thyroid nodule that appeared soft at SE, with score 2.

Figure 2

Malignant thyroid nodule that appeared hard at SE, with score 4.

Figure 3

Benign thyroid nodule that appeared soft at SE, with a strain ratio of 0.89 which corresponded with final histological diagnosis of benign nodule.

Figure 4

Malignant thyroid nodule that appeared hard at SE, with a strain ratio of 8.27, in the malignant range.

Figure 5

An example of a malignant thyroid nodule at 3D US and 3D SE; (a) the lesion appeared hypoechoic with ill marginated margins on three-axis planes; (b) and (c) the lesion appeared completely anelastic corresponding to score 4 at 3D USE with better delination of irregularity of the margins.

Figure 6

An example of a benign thyroid nodule which at 3D USE showed score 2.