Diagnostic Performances of the ACR-TIRADS System in Thyroid Nodules Triage: A Prospective Single Center Study

Abstract

Ultrasound scores are used to determine whether thyroid nodules should undergo Fine Needle Aspiration (FNA) or simple clinical follow-up. Different scores have been proposed for this task, with the American College of Radiology (ACR) TIRADS system being one of the most widely used. This study evaluates its ability in triaging thyroid nodules deserving FNA on a large prospective monocentric Italian case series of 493 thyroid nodules from 448 subjects. In ACR 1–2, cytology never prompted a surgical indication. In 59% of cases classified as TIR1c-TIR2, the FNA procedure could be ancillary, according to the ACR-TIRADS score. A subset (37.9%) of cases classified as TIR4-5 would not undergo FNA, according to the dimensional thresholds used by the ACR-TIRADS. Applying the ACR score, a total of 46.5% thyroid nodules should be studied with FNA. The ACR system demonstrated a sensitivity and specificity of 58.9% and 59% in the identification of patients with cytology ≥TIR3A, with a particularly high false negative rate for ACR classes ≥3 (44.8%, 43/96), which would dramatically decrease (7.3%, 7/96) if the dimensional criteria were not taken into account. In ACR 3–4–5, a correspondence with the follow-up occurred in 60.3%, 50.2% and 51.9% of cases. The ACR-TIRADS is a useful risk stratification tool for thyroid nodules, although the current dimensional thresholds could lead to an underestimation of malignant lesions. Their update might be considered in future studies to increase the screening performances of the system.

Use of Diagnostic Criteria from ACR and EU-TIRADS Systems to Improve the Performance of Cytology in Thyroid Nodule Triage

“…Various studies have shown the good performance of ACR-TIRADS in selecting thyroid nodules deserving FNA, stressing its high "rule-out" role, as confirmed by our group here and previous experience [1,6,8,[16][17][18]. In the present work, the ACR and EU-TIRADS systems recommended FNA in 46.5% (223/480) and 51.9% (249/480) of the nodules, respectively.…”

“…However, the only feature with a significant influence on diagnostic accuracy was the increased vascularization of the nodules, which is not taken into account by both the ACR and EU-TIRADS systems. Other recent studies investigated the impact of different dimensional cutoffs, e.g., ≤2 and >2 cm, on the final performances of the available US systems, showing a range of values quite close to the ones obtained in the present cohort with the ACR and EU-TIRADS systems [8,29]. An innovative approach was proposed in 2017 by He et al, creating a new algorithm that significantly increased the predictive performance of US features [30].…”

“…This prospective study included 448 consecutive patients who underwent 493 USguided FNA from January to June 2019 at the interventional radiology clinic, ASST Monza, Italy, during an Italian Association for Research on Cancer (AIRC)-granted project for the diagnosis of thyroid carcinoma [8]. All nodules were subjected to FNA, regardless of their ACR/EU-TIRADS scores, after an endocrinological clinical indication.…”

“…Indeed, the indication of a biopsy is influenced by subjectivity in US interpretation, different ROMs in the screened populations, and personalized clinical decisions [6,7]. On the other hand, defensive medicine, excessive scrupulousness, or limited experience could induce clinicians to perform FNA regardless of the TIRADS score, especially in large nodules, still depending on cytology for the final answer regarding the nature of a thyroid lesion and thus reducing the practical utility of TIRADS [8]. Although the most recent reports in the literature stress the recommendation to implement these algorithms in the clinical setting, the selection of more impactful radiological criteria may improve the contribution of these systems to risk assessments [6,[9][10][11].…”

“…Although the most recent reports in the literature stress the recommendation to implement these algorithms in the clinical setting, the selection of more impactful radiological criteria may improve the contribution of these systems to risk assessments [6,[9][10][11]. In this work, we present a comparative analysis of the most widely employed US classifications to support their systematic application in a first-level general hospital for the bioptic triage of thyroid nodules [8]. Moreover, the present paper supports the hypothesis that specific US features, coupled with cytological classes, might be better able predict the final malignant nature of a thyroid nodule.…”