Evaluation of the Performance of ACR TI-RADS Also Considering Those Nodules with No Indication of FNAC: A Single-Center Experience

Abstract

Background: Several US risk stratification score systems (RSSs) have been developed to standardize a thyroid nodule risk of malignancy. It is still a matter of debate which RSS is the most reliable. The purpose of this study is to evaluate: (1) the concordance between the American College of Radiology TI-RADS (ACR TI-RADS) and fine needle aspiration cytology (FNAC), (2) the cancer rate in the ACR TI-RADS categories, (3) the characteristics of nodules evaluated by FNAC even if not formally indicated according to ACR TI-RADS (‘not indicated FNACs”). Methods: From January 2021 to September 2022, patients attending the Endocrinology Unit of the CTO Hospital of Rome for evaluation of thyroid nodules were included. Results: 830 nodules had negative cytology, belonging to TIR2 and TIR1C. One hundred and thirteen nodules were determined to be suspicious for or consistent with malignancy belonging to TIR3B/TIR4/TIR5. Of this last group, 94% were classified as TR4/TR5 nodules. In total, 87/113 underwent surgery. Among these, 73 had histologically proven cancer, 14 turned out to be benign. “Not indicated FNACs” was 623. Among these, 42 cancers were present. Conclusions: This study confirmed the diagnostic power of ACR TI-RADS. In addition, these data suggest revising the ACR TI-RADS indication to FNAC, especially for TR4.

Meaning of ACR-TIRADS recommendation in favor of follow-up rather than FNAC in thyroid nodules

“…Then, some thyroid carcinomas may skip the FNAC indication according to their small dimension. Searching for the optimal size threshold indicate or not FNAC is a matter to debate, and several papers have been published on this topic [14][15][16][17][18]. Second, TIRADSs were built on the basis of PTC only and their accuracy has been proven against this cancer type [19].…”

Papillary thyroid carcinoma: ≤ 10 mm does not always mean pN0. A multicentric real-world study

“…Taking into account the above issues, to lower the burden on institutions, physicians, and patients, scientific societies do not recommend performing biopsies in very small thyroid nodules (i.e., maximum diameter less than 10 mm), even if they show suspicious characteristics of the US features [ 5 , 6 ]. This approach could avoid overdiagnosis and overtreatment of low-risk indolent papillary thyroid microcarcinoma (PTMC), but at the same time, it could also overlook the diagnosis of the aggressive ones in their early stages [ 7 ]. In fact, to date, there is no agreement on the clinical characteristics that can reliably discriminate patients with small but aggressive TC from the larger number of indolent PTMC [ 8 – 13 ].…”