The American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) improves the diagnostic performance of thyroid ultrasonography (US) for predicting malignant nodules, according to a multicenter study published in the European Journal of Radiology.
US is the best tool for diagnosing thyroid nodules, but it remains inaccurate in distinguishing between benign and malignant nodules, according to Mohammad Abd Alkhalik Basha, with the department of radio-diagnosis at Zagazig University, Zagazig, Egypt, and colleagues.
TI-RADS was originally created to improve patient management and avoid unnecessary fine needle aspiration biopsy (FNAB) in patients with thyroid nodules.
“However, its clinical use is still limited, and its application in clinical practice is questioned,” the researchers added.
Therefore, the team set out to assess the diagnostic validity and reproducibility of TI-RADS for interpreting thyroid nodules on US. They conducted their prospective study in a final cohort of 380 patients with 948 thyroid nodules detected by US between May 2017 and December 2018.
Three highly experienced radiologists independently analyzed the US exams, assigning each a TI-RADS category. Specifically, points were given to each nodule based on five categories; the sum of each category indicated the TI-RADS category for individual nodules. Two points indicated a nodule was “not suspicious” (TR2) while those with 7 points or more were “highly suspicious” (TR5). Cytology was used as a reference standard.
Overall, 136 nodules were malignant and 812 were benign. The most accurate cut-off value for predicting malignancy was greater than TR3. On a per-lesion basis, TI-RADS had a sensitivity, specificity and accuracy of 98.3%, 90.9% and 92.1%, respectively when predicting malignancy on nodules classified as greater than TR3.
Additionally, the researchers found a combination of TR4 and TR5 provided “remarkably good negative likelihood ratio, which support the value of ACR TI-TADS for avoiding unnecessary FNAB.”
“Therefore, we recommend the combination of TR4 and TR5 as a predictor for malignancy of thyroid nodules because if we consider TR5 alone as conclusive for malignant thyroid nodules diagnosis, the ACR TI-RADS will miss a relevant number of malignant thyroid nodules,” Basha et al. explained.
One of the most important limitations of the study, according to the researchers, was that TI-RADS remains uncommon and unfamiliar to clinicians. But, after explaining the meaning to several referring clinicians before the study, 90% considered TI-RADS a useful tool for clinical-decision making and referral following the study results.
“Based on our findings, which resembles those of previously published studies, the ACR TI-RADS is a categorized reporting of pattern recognition with several advantages: reduce mistakes of important data from US reports by standardizing report structure and content, decrease inconsistency in interpretation of thyroid nodules, increase contact with referring clinicians, help management procedures, and avoid unnecessary FNAB,” the authors concluded.