Impact of thyroid nodule sizes on the diagnostic performance of Korean thyroid imaging reporting and data system and contrast-enhanced ultrasound

This study aimed to evaluate the impact of thyroid nodule sizes on the diagnostic performance of Korean thyroid imaging reporting and data system (TIRADS) and contrast-enhanced ultrasound (CEUS).

In total, 308 consecutive patients with 382 thyroid nodules underwent US-guided FNA or surgery were included in this retrospective study. The nodule size was classified into 3 categories: ≤10 mm (group A), 10-20 mm (group B), and ≥20 mm (group C). We compared the risk of malignancy in each subgroup, categorized according to the TIRADS and CEUS patterns.

In group A, the differences in diagnostic value between TIRADS and CEUS were significant (AUC: 0.804 vs 0.733, P = 0.028, sensitivity: 81.8% vs 72.7%, P = 0.013, specificity: 88.9% vs 79.4%, P = 0.011). In group B, the AUC (0.897), sensitivity (88.1%) and specificity (91.9%) of CEUS were highest. In group C, the specificity of CEUS was significantly higher compared with TIRADS classification (90.8% vs 82.9%, P = 0.023), while the sensitivity and AUC showed no significant difference between the two models (84.2% vs 81.5%, P > 0.406, 0.848 vs 0.820, P = 0.545).

Nodule size influences the diagnostic accuracy of the two methods. TIRADS have best value in nodules ≤10 mm, while CEUS perform best for differentiating lesions >10 mm, especially in lesions ≥20 mm.