Endocrine Abstracts

JOINT3200

Background: In the evaluation of thyroid nodules, an ultrasound-based risk stratification system(RSS) is useful for identifying patients with a high likelihood of thyroid cancer and determining the need for fine needle aspiration biopsy (FNAB). However, these systems are primarily focused on diagnosing papillary thyroid carcinoma(PTC), the most common type of thyroid cancer. A new ultrasound-based RSS for the diagnosis of follicular thyroid carcinoma(FTC) has recently been proposed, known as F-TI-RADS. In this study, we compared this new system with existing systems for diagnosing thyroid cancer.

Methods: This retrospective study included 385 patients: 194 diagnosed with follicular thyroid carcinoma(FTC) and 191 diagnosed with follicular adenoma(FA), who underwent surgery for follicular neoplasms at Samsung Medical Center. Preoperative ultrasound examinations of the FA and FTC groups were reviewed and evaluated using K-TI-RADS, ACR TI-RADS, and F-TI-RADS. Additionally, we compared the usefulness of each system in screening for high-risk FTC by incorporating TERT promoter mutation information based on the WHO classification.

Result: The factors required to evaluate each RSS on preoperative ultrasound for all patients were compared between the FTC and FA groups. There were no significant differences in size (P = 0.685), composition (P = 0.054), or orientation (P = 0.349) between the two groups. However, significant differences were observed in the presence or absence of lobulation (P < 0.001), echogenicity (P < 0.001), margin characteristics (P = 0.003), calcification (P < 0.001), and trabecular formation (P < 0.001). When comparing the area under the curve (AUC) values of the TI-RADS systems, the AUC values were 0.635 for K-TI-RADS, 0.646 for ACR TI-RADS, and 0.658 for F-TI-RADS, with no statistically significant differences between these RSSs. Next, the patients were divided into two groups to evaluate the usefulness of the systems in screening for high-risk FTC. Group 1 included patients with FA, minimally invasive (MI) FTC, or encapsulated angioinvasive (EA) FTC with wild-type (WT) TERT, comprising 292 patients. Group 2 included patients with encapsulated angioinvasive (EA) FTC with TERT mutation or widely invasive (WI) FTC, comprising 28 patients. The AUC values for the RSSs in each group were as follows: 0.751 for K-TI-RADS, 0.783 for ACR TI-RADS, and 0.846 for F-TI-RADS.

Conclusion: When comparing the FTC and FA groups, the performance of the three RSSs was similar, However, F-TI-RADS demonstrated superior performance compared to the other RSSs in detecting high-risk FTCs.