Advanced Ultrasound Techniques in Preoperative Diagnostic of Thyroid Cancers

Abstract

The most precise evaluation of thyroid masses is by high-sensitive ultrasound. Complementary to B-mode ultrasound, elastography can add valuable information by determining tissue stiffness-an important predictor for malignancy. All major guidelines recommend nodules with high suspicious ultrasound characteristics larger than 1 cm to be addressed to ultrasound-guided fine needle aspiration biopsy (FNAB) to rule out malignancy. The main limitation of this procedure is represented by indeterminate cytology, which accounts for up to 20-25% of biopsy results. Molecular markers imply elevated costs and their performance needs further study. Elastography may be helpful in establishing the optimal therapeutic attitude for this cytological category. Currently, there are two ultrasound elastogra-phy methods available for assessing tissue stiffness using the parallel deformation to the applied force direction (strain) or the perpendicular deformation to the force direction (shear wave). These methods will be presented and compared in this chapter, with their indications and limitations for a better understanding of their application in nodular thyroid pathology.