Thyroid nodule malignancy risk comparison between different Thyroid Imaging and Reporting Data Systems (TIRADS)

Objectives: The aim of the study was to evaluate which of the following three TIRADS systems is more sensitive and accurate: the system used in Latvia (L-TIRADS), Europe (EU-TIRADS) and the Korean (K-TIRADS) system. Materials and Methods: A prospective study in which thyroid ultrasound and FNA biopsy results of 176 patients with 187 thyroid nodules according to the national guidelines for thyroid biopsy. 151 female (85.8 %) and 25 male (14.2%) patients were included in the study.
Each nodule was graded by all TIRADS systems and malignancy stratification comparison was performed based on malignant pattern presence by experienced radiologist. Results: 135 nodules (72.19%) were benign, 7 nodules (3.74%) were suspicious of malignancy, 17 nodules (9.09%) were malignant and 14 nodules (7.49%) were FNA non-diagnostic according to the Bethesdasystem. All TIRADS sys- tems have a high sensitivity (100%) for malignancy detection. However, L-TIRADS represents a higher specificity (67.5%), accuracy (71,7%) and AUC (83.7%), in comparison with EU-TIRADS (SPE=33.1%, ACC=41.7%, AUC=66.6%) and K-TIRADS (SPE=42.9%%, ACC=50.3%, AUC=71.5%). From ultrasonographic features, microcalcification was more sensitive – 87.5% (OR= 21.53; p<0.001). However, microlobulated or spiculated/ infiltrative contour was more accurate and with a better AUC 85.0% and 89.3% (OR=23.13; p<0.001), respectively. Conclusions: Microlobulated or spiculated/infiltrative contour have shown to be an ultrasonographic malignancy feature with the highest accuracy. One in three nodules with microcalcification and marked hypoechogenicity are ma- lignant. L-TIRADS represents higher specificity and accuracy in comparison to EU-TIRADS and K-TIRADS. Taking into account these results, L-TIRADS can be considered to be the thyroid imaging and reporting data system of a higher quality.