Endocrine Abstracts

Introduction: This study aims to assess the performance of ultrasound using Kwak-TIRADS as the primary diagnostic tool for estimating papillary thyroid carcinoma (PTC) risk in thyroid nodules within the high-prevalence region of Crete, Greece.

Methods: A retrospective analysis was conducted on 802 thyroid nodules collected between 2018 and 2021. Nodules were categorized based on Kwak-TIRADS and compared against the Bethesda System for Reporting Thyroid Cytopathology (BSRTC). TIRADS 4a/4b served as the cutoff for benign/malignant categorization. Bethesda II category was used as the benign standard reference, and Bethesda V & VI categories as the malignant. Ultrasound and cytology tests were performed by a single experienced radiologist and cytologist, respectively.

Results: Of 802 thyroid nodules, 549 (68.4%) were benign, and 185 (23%) were malignant on cytology. The majority of nodules (n=391; 48.7%) were classified as TIRADS 4a. Overall accuracy stood at 76.9%. Concordance rates between TIRADS 2, 3, 4a, and Bethesda II were 81%, while for TIRADS 4b, 4c, 5, and Bethesda IV & V, it was 62.2%. Excluding TIRADS 4 subcategories improved accuracy to 93.6% and 77.3%, respectively. The probability of a malignant fine-needle aspiration cytology (FNAC) was 77.33%, 60%, 43.63%, 18.67%, 1.29%, and 0% for TIRADS 5, 4C, 4B, 4A, 3, and 2, respectively. The probability of a benign FNAC was 100%, 93.53%, 73.4%, 41.81%, 24.44%, and 9.33% for TIRADS 2, 3, 4A, 4B, 4C, and 5, respectively. Sensitivity, specificity, and positive likelihood ratio were 58.9%, 92.5%, and 7.89, respectively. Excluding TIRADS 4, sensitivity increased to 95%, and specificity to 96.9%.

Conclusion: The study affirms strong concordance between Kwak-TIRADS and BSRTC, endorsing ultrasound as an effective first-line tool for thyroid nodule risk assessment. Notably, considering more ultrasound and clinical data in TIRADS 4 subcategories may optimize diagnostic accuracy. Kwak-TIRADS, characterized by simplicity and implementability, emerges as a reliable method for thyroid malignancy risk stratification.