Chapters authored
Advanced Ultrasound Techniques in Preoperative Diagnostic of Thyroid Cancers
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 elastography 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.
Part of the book: Knowledges on Thyroid Cancer
Elastography Methods in the Prediction of Malignancy in Thyroid Nodules
Ultrasonography provides a primary stratification of the malignancy risk of thyroid nodules for selecting those that need further evaluation by fine-needle aspiration cytology (FNAC). Ultrasound elastography (USE) methods have been more recently proposed as a promising tool, aiming to increase the accuracy of baseline ultrasound. By means of USE, stiffness is assessed as an indicator of malignancy. Strain elastography was the first method used in thyroid imaging, with very good accuracy in discerning thyroid cancer. More recently, 2D shear-wave elastography also confirmed to be a valuable tool with similar outcomes. The advantages, limitations, and technical details of the elastography methods currently used in assessing thyroid morphology, particularly thyroid nodules, will be presented and compared in this chapter.
Part of the book: Elastography