Diagnostic value of multiparametric ultrasound and the EU-TIRADS system for differentiation of focal thyroid lesions

Background. Over the last 15 years, there have been many recommendations for the management of patients with thyroid nodules, based on the assessment of various ultrasound (US) criteria in B-mode. In 2020, the EU-TIRADS system (2017) was included in Russian Clinical Practice Guidelines. Shear wave elastography (SWE) increases the diagnostic efficacy of ultrasonic B-mode examination of thyroid nodules and can be recommended to be included in the current classification system.

Objective. The study aims to assess the diagnostic efficacy of multiparametric US combining SWE and color flow mapping in differentiating between benign and malignant thyroid nodules to define their stage according to the EU-TIRADS system and decide on the need for fine-needle aspiration biopsy.

Material and Methods. A total of 150 thyroid nodules from 116 patients were analyzed. Lesions were then classified according to the EU-TIRADS system, SWE with an assessment of the color map and tissue stiffness was performed (Emean). In all tumors, cytological and histological (in operated patients) verification was carried out.

Results. After B-mode US with color flow mapping, differentiation of palpable thyroid abnormalities by the EU-TIRADS system was carried out. 78 nodules were classified as EU-TIRADS 2 (52%), 42 as EU-TIRADS 3 (28%), 26 as EU-TIRADS 4 (17.3%), 4 as EU-TIRADS 5 (2.7%). On cytological examination 42 tumor nodules were detected. Of these, 6 (14.3%) cases were reported as papillary thyroid carcinoma, 36 (85.7%) as follicular neoplasm, 22 (61%) among the last prove to be follicular carcinoma. Qualitative and quantitative evaluation of elastograms was performed. Benign nodules were colored primarily in blue, while suspicious for malignancy revealed red areas of different size. Elasticity index in benign nodules was 24.3 ± 5.63 kPa for colloid goiter, 27.8 ± 6.35 kPa for cellular goiter; in suspicious for malignancy this index was 80.9 ± 50.9 kPa for follicular neoplasm, 114 ± 56.8 kPa for papillary thyroid cancer. The stiffness cutoff value for malignancy indicated with ROC-analysis was estimated as 45.4 kPa. Mean elasticity index (kPa) was significantly higher in suspicious for malignancy nodules than in benign nodules (р < 0.05). Of 120 (80%) nodules, primarily assessed as benign and defined as EU-TIRADS 2 and 3, 18 (12%) nodules after SWE revealed areas of high stiffness exceeding the cutoff value. After that, these nodules were transferred to EU-TIRADS 4 and 5, and these stages require fine-needle aspiration. Of these, 11 (7.3%) cases were reported as follicular neoplasm, 6 (4%) among the last prove to be follicular thyroid carcinoma.

Conclusion. Using multiparametric approach with SWE will give the opportunity to classify correctly the nodule according to the EU-TIRADS and to identify greater number of thyroid tumors for fine-needle aspiration. SWE made it possible to increase the specificity of US using the EU-TIRADS system. The characteristics of the SWE score were: sensitivity = 81%, specificity = 90.3%, positive predictive value = 88%, negative predictive value = 91%, and accuracy of comprehensive study = 88.4%.

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