The studies on the effectiveness of various TIRADS in the diagnostics of thyroid nodules differ in the method of ultrasound image assessment: real time (rtUS) vs. static ultrasonography (stUS). The aim of the study was to evaluate the impact of those two methods on the categorization of nodules in EU-TIRADS. Three experienced raters assessed 842 nodules in routine rtUS and reassessed with the use of sUS. Reproducibility of the assessment of malignancy risk features and categorization of nodules with EU-TIRADS was estimated with Krippendorff's alpha coefficient (Kα). The reproducibility of EU-TIRADS categories on sUS in relation to rtUS was in range 70.9-76.5% for all raters (Kα: 0.60-0.68) with the highest reproducibility for category 3 (80.0-86.5%) and the lowest for category 5 (48.7-77.8%). There was a total disagreement of the identification of microcalcifications on sUS in relation to rtUS, a strongly variable reproducibility of marked hypoechogenicity (12.5-84.6%, Kα: 0.14-0.48) and a tendency toward more frequent identification of the non-oval shape on sUS. The percentage of agreement for each pair of raters in assigning the EU-TIRADS category on sUS was in the range 71.6-72.3% (Kα: 0.60-0.62). The method of sonographic image evaluation influences the nodule's feature assessment and, eventually, the categorization within EU-TIRADS.
Keywords: EU-TIRADS; real-time ultrasonography; static ultrasonography; thyroid; thyroid cancer.