Thyroid cancer is a tumour with a steadily increasing incidence. It accounts for 7% to 15% of focal lesions detected by ultrasound, depending on age, gender and other factors affecting its occurrence. Fine-needle aspiration biopsy is an essential method to establish the diagnosis but, in view of its limitations, sonoelastography is seen as a non-invasive technique useful in differentiating the nature of lesions and monitoring them after fine-needle aspiration biopsy. This paper presents a literature review on the role of both sonoelastographic techniques (relative strain sonoelastography, shear wave sonoelastography) to assess the deformability of focal thyroid lesions. Ultrasound examination is a relatively subjective method of thyroid imaging, depending on the skills of the examiner, the experience of the centre, and the quality of equipment used. As a consequence, there are inconsistencies between the results obtained by different examiners (