Deciphering <scp>EU</scp> ‐ <scp>TIRADS</scp> : A Pictorial Guide to the Spectrum of Thyroid Nodules

ABSTRACT Thyroid nodules are frequently encountered in clinical practice, with ultrasound playing a central role in their initial evaluation and risk stratification. While most nodules are benign, distinguishing potentially malignant nodules is important. The EU‐TIRADS classification system, introduced in 2017, offers a simplified framework based on sonographic features such as composition, echogenicity, margins, shape, and echogenic foci. The classification is highly sensitive, with a good negative predictive value, particularly in nodules ≥ 10 mm. Its performance in nodules &lt; 10 mm is less robust. Compared to the American College of Radiology's ACR‐TIRADS, which uses a point‐based system and generally results in fewer fine needle aspirations (FNAs), the use of EU‐TIRADS leads to more biopsies but captures more malignant nodules. Both systems have high sensitivity but modest specificity, with overlap in the features they assess. Key challenges remain, including inter‐observer variability and the interpretation of equivocal features such as vascularity and mild hypoechogenicity. Misleading appearances, often mimicking malignancy due to nodule scarring or retraction, further complicate assessment. While both EU‐TIRADS and ACR‐TIRADS offer valuable frameworks for clinical decision‐making, understanding their limitations and nuances is essential for accurate diagnosis and appropriate management of thyroid nodules. In this paper, we aim to explain thyroid nodule classification systems, with a specific focus on the EU‐TIRADS system.