ACR TI-RADS and ATA ultrasound classifications are helpful for the management of thyroid nodules located in the isthmus.

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.