Purpose: To compare the application value of the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) and the American Thyroid Association (ATA) guidelines in the risk stratification of thyroid isthmic nodules.
Methods: A total of 315 patients with thyroid isthmic nodules (315 nodules) confirmed by surgical pathology or fine-needle aspiration biopsy (FNAB) were selected in this retrospective study. The nodules were evaluated and classified according to ACR TI-RADS and the ATA guidelines. Taking pathological results as the reference, receiver operating characteristic (ROC) curves were drawn to evaluate the diagnostic capabilities of the ACR TI-RADS and the ATA guidelines for the risk stratification of thyroid isthmic nodules. The unnecessary biopsy rates and false-negative rates were compared.
Results: Multivariate analysis of ultrasonographic features of suspicious malignancies showed that an aspect ratio > 1 was not an independent risk factor for malignant thyroid nodules located in the isthmus (odds ratio: 3.193, 95%confidence interval: 0.882-11.552) (P = 0.077). The area under the ROC curves for diagnosing malignant thyroid nodules located in the isthmus in by the ACR TI-RADS and the ATA guidelines were 0.853 and 0.835, respectively. Under the management recommendations of the ACR TI-RADS and ATA guidelines, the false-negative rates of malignant thyroid nodules were 66.2%(ATA intermediate suspicion), 62.3%(ACR TR 4), 81.8%(ATA high suspicion) and 86.5%(ACR TR 5).
Conclusion: Both the ACR TI-RADS and the ATA guidelines have high diagnostic capabilities for the risk stratification of thyroid isthmic nodules. For ACR TR 4 and 5 and ATA intermediate- and high-suspicion thyroid isthmic nodules with a maximum diameter < 1 cm, the criteria for puncture should be lowered, and FNAB should be done to clarify their diagnosis.
Keywords: ACR TI-RADS; ATA; isthmus; thyroid nodule; ultrasound.