The ACR Thyroid Imaging Reporting and Data System (TI-RADS) is the latest addition to the College’s growing library of reporting and data system documents, which promote standardization in terminology, report organization, classification and management, and data collection in imaging findings.
ACR TI-RADSTM provides guidance on the management of thyroid nodules detected on ultrasound. Its goal is to promote consistency in recommendations and reduce the number of thyroid biopsies — a procedure that doubled between 2006 and 2011, partly due to an increase in non-thyroid-related neck imaging.
The conundrum with thyroid nodules is that they are fairly common but mostly harmless, according to Franklin N. Tessler, MD, professor emeritus of radiology at the University of Alabama and chair of the TI-RADS Committee.
“They can be found with high-resolution ultrasound in close to 70 percent of adults, but the vast majority of these nodules are benign,” says Tessler. “Even the most predominant form of thyroid cancer — papillary thyroid cancer — tends to be relatively non-aggressive.”
Despite the low likelihood of harm, once discovered, thyroid nodules are usually still evaluated for malignancy. Patients often undergo invasive follow-up procedures such as fine-needle aspiration and — in up to 30 percent of biopsied patients — partial thyroidectomy to obtain a definitive diagnosis, says Tessler. The marked increase in imaging over the past two decades has exacerbated the problem.
“We are definitely doing too many biopsies.” says Jenny K. Hoang, MD, associate professor of radiology and radiation oncology at Duke University and a member of the ACR TI-RADS Committee. “The practice doesn’t make sense given the low risk of malignancy and what we were subjecting patients to — the time, the costs of work-up, unnecessary surgery for benign nodules, and the anxiety for the patient.”
According to a New England Journal of Medicine editorial, between 2003–2007, overdiagnosis of thyroid cancer accounted for 70–80 percent of cases in women and 45 percent of cases in men in the United States. “Basically, it’s finding a lot of disease that the patient would have been better off not knowing about,” says Tessler of the trend. “That is not good medicine nor is it a good use of resources.”
One factor contributing to the exploding number of biopsies was the absence of clearly established guidance on the topic, despite the existence of recommendations from several other medical societies, says Hoang. They all had different evaluation methodologies, some were difficult to follow, and none were universally adopted across the medical field. This led to uncertainty, inconsistency in thyroid nodule management and an increased reliance on biopsy at low thresholds, says Hoang.
In an effort to improve existing practices and reduce unnecessary biopsies of benign nodules, the ACR embarked on a three-part process that resulted in the publication of a white paper on incidental thyroid nodules, the creation of a standardized lexicon for reporting nodules on thyroid ultrasound, and the publication of ACR TI-RADS in the spring of 2017.
Distinguishing features of TI-RADS are higher size thresholds to biopsy, a specific follow-up plan for nodules that are not biopsied, and use of a points-based system to evaluate thyroid nodules instead of the pattern-based system endorsed by other guidelines.
According to Tessler, this approach allows for the evaluation of more nodules. In pattern-based systems, nodules are classified based on how closely they resemble one of multiple patterns. Some nodules cannot be evaluated because they do not match any of the patterns presented. In points-based systems, nodules are numerically rated based on their characteristics, so all can be assessed. This means more nodules get evaluated, further reducing the need for biopsies. The idea is to “leave no nodule behind,” says Tessler.
Widespread adoption of TI-RADS is challenged by its need to distinguish itself in an already crowded field. The hope is that as practices implement the system, resulting data will demonstrate its advantages and lead to increased adoption.
ACR TI-RADS is a step toward addressing the “perfect storm” for thyroid nodules, says Hoang. Tessler adds, “I’ve never seen a patient unhappy about not having a thyroid nodule biopsy.”