Role of ultrasonography and ultrasound elastography in the evaluation of thyroid nodules

Introduction: Thyroid nodules are frequently encountered with its Incidence is increasing steadily. Most nodules are benign and <5% of nodules are malignant. High-Resolution Ultrasonography (HRUS) is the most sensitive imaging test available for the examination of the thyroid gland to detect thyroid lesions accurately. Ultrasonography (US) is relatively cheap, easily accessible, rapidly performed and has an advantage of no exposure to ionising radiation. Sonoelastography (SE) is a relatively new non-invasive technique for imaging stiffness or elasticity of the tissue by measuring movement or deformation of tissue in response to a small applied pressure. Aim: To assess the diagnostic performance of conventional ultrasonography, colour mapping and strain ratio using SE for characterising thyroid nodules. Materials and Methods: A prospective study was conducted from October 2015 to August 2017 in which 65 patients were examined. All age group patients who were referred for thyroid ultrasonography and detected to have a thyroid nodule which was subsequently confirmed by FNA/histopathology were included in the study. Test of significance was assessed using the chi-square test, p<0.05 was considered significant. Results: FNA/HPE revealed 14 (21.5%) malignant (six papillary carcinomas, three poorly differentiated carcinoma, two anaplastic carcinomas and three follicular carcinomas) and 51 (78.5%) benign nodules. Out of these 14, 13 (92.9%) cases were found in patients above 50 years and only 1 (7.1%) case was found below 50 years. Calculation of strain ratio was done between the thyroid nodule and the surrounding thyroid tissue at the same depth. Significant differences were seen between the strain ratios for the benign and malignant lesions (p<.001). By using ultrasound elastography score malignancy was seen in 81.3% of malignant nodules. Conclusion: Ultrasonography is a cost-effective modality of imaging and also the investigation of choice in thyroid nodules. Elastography has proven to be a good adjunct tool in assisting USG in the diagnosis and differentiation of benign versus malignant nodules.