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Numerous scientific societies around the world have published their TIRADS (Thyroid Imaging Reporting and Data System) classifications that evaluate the risk of malignancy of focal thyroid lesions, presenting different ultrasound features for each category and lesion size thresholds to determine eligibility for biopsy. The use of such risk estimation systems in focal thyroid lesions facilitates the reporting of thyroid ultrasound findings and improves the qualification of focal lesions for fine-needle aspiration biopsy (FNAB). In this publication, the three most popular TIRADS classifications, European – EU-TIRADS, Korean – K-TIRADS, and developed by the American Society of Radiology – ACR-TIRADS, are presented and discussed based on a literature review. The results of available head-to-head statistical analyses comparing the classifications are also presented. The advantage of the EU-TIRADS and K-TIRADS systems is that they include only the most important ultrasound features, so their application is not time-consuming, and the scores are easy to incorporate into clinical practice. ACR-TIRADS, unlike other scales, is based on a unique classification system and represents the most comprehensive classification. Each of the five categories of ultrasound features – morphology, echogenicity, shape, margins, microcalcifications – are evaluated and assigned a score from 0 to 3, with a higher score being associated with a higher risk of cancer. Based on the available data, the greatest benefit has been demonstrated for the ACR-TIRADS classification, which also has implications for minimising the number of unnecessary FNABs. However, limitations related to the heterogeneity of the groups analysed in the study, including differences in the populations studied, inclusion criteria, proportions of patients of either sexes, and the number of malignant lesions analysed, should also be taken into account.

Thyroid cancer is a tumour with a steadily increasing incidence. It accounts for 7% to 15% of focal lesions detected by ultrasound, depending on age, gender and other factors affecting its occurrence. Fine-needle aspiration biopsy is an essential method to establish the diagnosis but, in view of its limitations, sonoelastography is seen as a non-invasive technique useful in differentiating the nature of lesions and monitoring them after fine-needle aspiration biopsy. This paper presents a literature review on the role of both sonoelastographic techniques (relative strain sonoelastography, shear wave sonoelastography) to assess the deformability of focal thyroid lesions. Ultrasound examination is a relatively subjective method of thyroid imaging, depending on the skills of the examiner, the experience of the centre, and the quality of equipment used. As a consequence, there are inconsistencies between the results obtained by different examiners (inter-observer variability) and by the same examiner (intra-observer variability). In this paper, the authors present a review of the literature on inter-observer and intra-observer variability in the assessment of individual features of ultrasound imaging of focal lesions in the thyroid. In addition, the authors report on an analysis of cut-off thresholds for the size of lesions constituting the basis for fine-needle aspiration biopsy eligibility assessment. The need to diagnose carcinomas up to 10 mm in diameter is highlighted, however a more liberal approach is recommended in terms of indications for biopsy in lesions associated with a low risk of malignancy, where, based on consultations with patients, active ultrasound surveillance might even be considered.

Aim:The aim of this study was to evaluate the inter- and intra-observer variability and accuracy of ultrasound assessment of thyroid nodules using a descriptive lexicon. Materials and methods:A prospective study was performed on complete ultrasound examinations, including sonoelastography and color Doppler ultrasound of 18 patients with 20 thyroid nodules. A total of 20 records of thyroid nodules from these techniques were duplicated, numbered, and randomly arranged. Five radiologists assessed the recordings independently. Cohen Kappa and Fleiss Kappa statistics were used to determine the degree of intra- and inter-observer agreement. Results:Mean accuracy rates for all radiologists, for all ultrasound features, ranged from 82.7 to 87.8%. For B-mode and strain elastography, accuracies ranged from 65.0 to 100% and 47.4 to 86.8%, respectively. Concerning intra-observer variability, three radiologists demonstrated almost perfect agreement (the ?-value ranged from 0.81 to 0.86), and a substantial agreement was noted for the two remaining radiologists. The ?-values for inter-observer agreement ranged from 0.61 for macrocalcifications (substantial agreement) to 0.33 for Asteria four-point elastography scale criteria (fair agreement). Conclusions:The results suggest relatively good inter-observer and excellent intra-observer agreement in the assessment of thyroid nodules using ultrasound, and fair agreement in the case of strain elastography.