Dear Editor,

We read with great interest the recently published article titled “Effect of the size of benign thyroid degenerative nodules on ACR TI-RADS categories” [1]. The study enrolled benign thyroid degenerative nodules and aimed to reveal the correlation between their sizes and 2017 ACR Thyroid Imaging Reporting and Data System (TI-RADS) categories [2].

However, the clinical utility of ACR-recommended size thresholds for fine-needle aspiration (FNA) in TI-RADS 3 and TI-RADS 4 nodules could not be evaluated based on the present data. According to the maximum diameter (D), the authors divided the nodules into three groups: 0.5 cm ≤ D ≤ 1 cm, 1 cm < D ≤ 2 cm, and D > 2 cm. However, the ACR-recommended size thresholds for FNA in TI-RADS 3, TI-RADS 4, and TI-RADS 5 categories are ≥ 2.5 cm, ≥ 1.5 cm and ≥ 1 cm, respectively [2]. The present data can only clarify the clinical utility of the ACR-recommended size thresholds for FNA in TI-RADS 5 nodules (≥ 1 cm). For TI-RADS 3 and TI-RADS 4 nodules, the clinical utility of ACR-recommended size thresholds for FNA (≥ 2.5 cm and ≥ 1.5 cm, respectively) cannot be assessed. If the authors could further add groups of 1.5 cm < D ≤ 2.0 cm and D ≥ 2.5 cm (expanding the data in Table 4), or regroup by ACR-recommended size thresholds of 2.5 cm, 1.5 cm, and 1 cm, it will be helpful for readers to assess the clinical utility of ACR-recommended size thresholds for FNA in TI-RADS 3 and TI-RADS 4 nodules.

Another issue is to determine whether there were patients with multiple nodules. Benign thyroid degenerative nodules may be multiple [3, 4]. The study included a total of 174 nodules from 174 patients, indicating that one nodule per patient was included in the study. However, the authors did not clarify whether there were patients with multiple nodules and how to enroll the target nodule if someone had multiple nodules (e.g., largest diameter or highest ACR category, or other criteria?). ACR also provides FNA recommendation for patients with multiple nodules [2]. Was the study performed according to the recommendation? It is necessary for the authors to address the issue in the Methods section.

We congratulate the authors on publishing their work in Journal of Medical Ultrasonics and sincerely hope that they can consider our suggestions in their future research.