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

Purpose: With the widespread use of imaging tests, the frequency of thyroid nodule identification has also increased. Thyroid nodules are very common in the whole population and are detected by ultrasonography in 50-60% of the population [1].
Ultrasonography currently is the best available method for the findings of nodules and its main purpose is to differentiate benign nodules from those at risk of malignancy and requiring ultrasound-guided fine-needle aspiration biopsy (FNA) to make a definitive diagnosis and decide about the necessity of surgical intervention.
Thyroid Imaging and Reporting Data Systems (TIRADS) are crucial to patients during thyroid ultrasonography because they can help to evaluate the necessity of thyroid nodule fine-needle aspiration biopsy (FNAB). Numerous TIRADS evaluation systems have been devised in the world. Kwak et al. system, which was created in 2011, is being updated and modified version used in Latvia; however, none of the TIRADS systems is a hallmark [2]. The aim of the study is to evaluate which of the following three TIRADS systems is more sensitive and accurate: the system used in Latvia (L-TIRADS), Europe (EU-TIRADS), or the Korean TIRADS (K-TIRADS) system [2, 3, 4]. Methods and materials: A prospective study in which thyroid ultrasound and FNA biopsy results of 176 patients from Clinical University Hospital and two private clinics were analyzed. IBM SPSS software, 22.0 version (IBM Corm., Armonk, N.Y., USA), MS Excel 2010 software, and MedCalc Software Ltd 19.2.1 version (Mariakerke, Belgium) was used to analyze statistical data and create graphs. The statistical significance level of this study was assumed to be p-value < 0.05. Ultrasonographic malignancy signs: markedly hypoechoic, irregular borders, macrocalcifications, taller than wide shape (AP>LL), specific lymphadenopathy. Ultrasonographic malignancy signs that do not change the TIRADS category: mildly hypoechoic, solid structure, chaotic central type vascularisation, higher stiffness with elastography (if available). Ultrasonographic malignancy risk-reducing signs: cystic structure, perinodular “halo” sign. Results: 176 patients with 187 nodules, from which 151 female and 25 male were included in the study. 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 non-diagnostic cytologically according to the Bethesda system. All TIRADS systems showed high sensitivity–100%. However, L-TIRADS is more accurate (71.7%) and with a better AUC (83.7%) compared to the EU-TIRADS (ACC=41.7%; AUC=66.6%) and K-TIRADS (ACC=50.3%; AUC=71.5%). There are multiple US malignancy suggesting features, out of all microlobulated or spiculated/infiltrative contour showed high sensitivity, accuracy and AUC value – 79.2%, 85.0%, and 89.3%. As well microcalcifications showed high sensitivity and AUC value – 87.5%, 78.6%. Discussion: Among all TIRADS classifications, only the L-TIRADS AUC value was 83.7%, which is why L-TIRADS is a better Thyroid Imaging Reporting and Data System comparison to EU-TIRADS (AUC= 66.6%) and K-TIRADS (AUC=71.5%). Due to the L-TIRADS had higher AUC, specificity, and accuracy, L-TIRADS can be considered as a better system for assessing the risk of thyroid malignancy. Based on the results of our study and the latest published studies on the comparison of malignancy-risk systems of thyroid nodules, it can be concluded that the L-TIRADS classification is of higher quality and with higher diagnostic efficiency [5, 6]. Several studies, including a study of 4,186 patients, have found a strong association between thyroid carcinoma, particularly micropapillary carcinoma, and microcalcifications in the thyroid gland (SPE 96.5%) [7]. This study cohort thyroid nodules with microcalcifications included 40 nodes (65.57%) benign, and 21 nodes malignant (34.43%), thus it can be concluded that one in three nodes with microcalcifications were malignant. Out of the 18 nodules with a microlobulated contour, 64.3% were benign and 35.7% were malignant, as well as thyroid nodules with spiculated/infiltrative contour - 4 nodules (44.4%) were benign, and 5 nodules (55.5%) were malignant. Due to the small proportion of patients in these categories, it is not appropriate to assume these results as absolute diagnostic endpoints. Referring to the 2018 study investigating the correlation of US malignancy features with cytopathological findings by Arpana et al., it was confirmed that several patterns such as nodule consistency, size, echogenicity, including nodule edge and contour, are important factors in distinguishing benign and malignant nodules [8]. Conclusion: A statistically significant difference of TIRADS systems performance has been defined: L-TIRADS (modified K-TIRADS) represents higher accuracy and a better AUC - 81.8% un 88.8%. EU-TIRADS and K-TIRADS show higher sensitivity – 95.8% and 91.7%, respectively. Microlobulated or spiculated/infiltrative contour has been shown to be an ultrasonographic malignancy feature with the highest sensitivity, specificity, and accuracy - 79.2%, 85.9%, and 85.0% (OR=23.13; p<0.001), as well as with a better AUC– 89.3%.