Endocrine Abstracts

Objectives: To assess whether the degree of heterogeneity of thyroid nodules defined by their elastographic characteristics is related to the cytological diagnosis and ultrasound classification of risk of malignancy.

Material and Methods: Observational, prospective study. 101 thyroid nodules were analysed by quantitative elastographic analysis (shear-wave), measuring the stiffness of the lesion by global elastography and its standard deviation (s.d.) as an index of the stiffness heterogeneity. US-guided FNA was performed and cytological analysis was confirmed by experienced pathologist, based on the Bethesda system 2017 for reporting thyroid cytopathology.

Results: 101 nodules, with an average volume of 5.02 ± 7.01cc, average elasticity of 41.82 ± 28.64 kPa and an average s.d. 19.81 ± 13.61 kPa. The ultrasound characterization of malignancy risk was based on the ACR TI-RADS system 2017, obtaining 19.8% of the nodules as TR2, 26.7% as TR3, 38.6% as TR4 and 14.9% as TR5. After the cytological study 3% of lesions were characterized as non-diagnostic (Bethesda I), 80.2% as benign (BII), 1% as atypia of undetermined significance or follicular lesions of undetermined significance (BIII), 3% as follicular neoplasms or suspicious for a follicular neoplasms (BIV), 3% as suspicious for malignancy (BV) and 9.9% as malignant (BVI). Both higher mean elastographic values and greater heterogeneity of nodules (higher s.d.) were significantly correlated with the ultrasound risk of malignancy and cytological malignancy, with areas under the curve (AUC) in ROC curves of 0.83 and 0.8, respectively, and a NPV of 0.95.

Conclusions: The stiffer nodules and with greater tissue heterogeneity present a greater potential for malignancy, so that analysis of the absolute elastographic value and its intranodular variability can contribute to the differential diagnosis of malignant thyroid nodular pathology. Because of its high NPV, the analysis of tissue stiffness heterogeneity could be a useful tool in the monitoring of benign nodules.