Role of Ultrasound Elastography in Evaluating Suspicious Thyroid Nodules

Ultrasound elastography is a promising new technique in the evaluation of the thyroid nodule. It allows for "virtual palpation" of the nodule, even smaller ones which may not be otherwise palpable clinically. Ultrasound elastography was developed to obtain information on tissue stiffness non-invasively. Due to the superficial location of the thyroid gland, lack of sonological interferences like bowel gas shadow, easy availability of USG, and no need for patient preparation, it is easy and feasible to obtain information regarding the stiffness in the organ or nodule objectively, even by beginners. Elastography is a technique that uses ultrasound to analyse the elasticity of a nodule by measuring the amount of distortion that occurs when the nodule is subjected to external pressure. Shear wave elastography (SWE) provides quantitative assessment in the form of elasticity indices (E _maximum, E _mean, E _minimum), and the stiffness of thyroid nodules can be evaluated with shear wave elastography. Malignant thyroid nodules tend to have higher shear wave elastography index. This was a prospective study. All patients with suspicious thyroid nodules who presented to head and neck oncology OPD with thyroid swelling with TIRADS score 3 or 4 and Bethesda III/IV were evaluated from December 2022 to February 2023. All the patients were screened with ultrasound, and reporting was done as per the ACR TIRADS reporting system following which elastography score was given based on the stiffness of the nodule. They further underwent FNAC from the suspicious thyroid nodule. Thyroidectomy was done as per department protocol. Twenty-four patients (38 nodules) were evaluated. There were seven males and 17 female patients included in the study. There were 23 malignant nodules in the final histopathology of the resected specimen. The sensitivity of TIRADS was 82.6%, specificity was 80%, for elastography specificity was 69.6%, sensitivity was 60%, for BETHESDA specificity was 66.7%, and sensitivity was 81.3%. The combined sensitivity and specificity for all three modalities combined were 93.33% and 95.6%. Receiver operator curve (ROC) analysis showed the area under the curve for USG TIRADS was 0.895, for elastography was 0.879, and for FNAC Bethesda was 0.902. AUC for combined tests ES + BETHESD was 0.800 (p = 0.013), TIRADS + BETHESDA was 0.833(p < .01), and for TIRADS + ES + BETHSDA AUC was 0.967 (p = 0.00). Ultrasound elastography can be used as an adjunctive tool along with routine grey scale ultrasound for characterising suspicious thyroid nodules.