Radiologists Call for Consensus on Thyroid Nodule Guidelines

Damian McNamara

April 19, 2016

LOS ANGELES — The Thyroid Imaging Reporting and Data System (TI-RADS), modeled on the BI-RADS classification of breast lesions, has the highest diagnostic accuracy for stratifying thyroid nodules, according to a comparison of guidelines for fine-needle aspiration biopsy of the thyroid.

"This supports the use of TI-RADS and highlights the need for consensus guidelines," said investigator Hannah Chung, MD, from the University of California, Los Angeles, who presented the findings here at the American Roentgen Ray Society 2016 Annual Meeting.

There is currently no clear picture on which suspicious-looking nodules on ultrasound should lead to fine-needle aspiration biopsy for cancer because guidelines from major radiology and endocrinology societies differ.

Alrough the guidelines identify some of the same characteristics that should raise suspicion — shape, composition, and echogenicity — without true consensus, specialists generally rely on different factors when recommending further workup for patients.

To assess diagnostic accuracy, Dr Chung and her colleagues compared guidelines for fine-needle aspiration biopsy from the American Thyroid Association (ATA) and the Society of Radiologists in Ultrasound (SRU) with TI-RADS.

Comparing Guidelines

The retrospective study involved the evaluation of 1047 nodules from 888 consecutive patients referred for fine-needle aspiration biopsy. The median size of the diagnostic thyroid nodules was 2 cm. The cohort was 79% female, and the median age of the patients was 57 years.

The investigators used TI-RADS classifications to rank the risk potential for each nodule on a 1 to 5 Likert scale, where 1 indicates low suspicion and 5 indicates almost certain malignancy.

It turns out that TI-RADS is more accurate than the ATA or SRU guidelines.

Table. Diagnostic Accuracy for 1047 Thyroid Nodules

Criteria Nodules Meeting Criteria, % Diagnostic Yield, % Accuracy, %
ATA guidelines 58.0 15.6 48.0
SRU guidelines 61.0 10.7 40.0
TI-RADS score of 3–5 39.0 22.0 66.0

 

On analysis of the receiver operating characteristic (ROC) curve, "TI-RADS-based sonographer suspicions outperformed ATA guidelines, and the ATA outperformed the SRU," Dr Chung reported. All differences were significant (P < .001).

The retrospective design of the study and possible referral bias are potential limitations of the study, she pointed out.

 
Size may not be as important a descriptor as previously thought.
 

Clinical guidelines are important because "thyroid nodules are very common," said Dr Chung. "Relative to the number of nodules that can be detected, there is a low frequency of malignancies, generally 9% to 13% in published literature." In their cohort, the malignancy rate was 12%.

"All the guidelines include size for fine-needle aspiration biopsy except for TI-RADS," she explained. But "size may not be as important a descriptor as previously thought."

In a previous study of the thyroid imaging, malignancy was shown to be significantly correlated with solid component, hypoechogenicity or marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, and taller-than-wide shape (Radiology. 2011;260:892-899).

Study investigator Nelly Tan, MD, also from UCLA, said she supports a single multidisciplinary guidance. "Given the overlap between ATA, SRU, and TI-RADS, our study advocates an intersociety consensus guideline, rather than separate guidelines, as it is now," she told Medscape Medical News.

An American College of Radiology (ACR) committee is currently compiling evidence to develop standardized terminology and classifications (J Am Coll Radiol. 2015;12[12 Pt A]:1272-1279). Their recommendations are expected later this year.

The study by Dr Chung's team "underlines the need to have TI-RADS," said session moderator Stephanie Coquia, MD, from Johns Hopkins University in Baltimore.

Discussions about thyroid nodules are "pretty multidisciplinary at Johns Hopkins," Dr Coquia told Medscape Medical News. In the meantime, she said, "I take my cues from my endocrinology colleagues. In their notes, they write things like 'as per the ATA guidelines'."

She said she applauds the effort of the ACR to develop standardized TI-RADS guidance.

Dr Chung, Dr Tan, and Dr Coquia have disclosed no relevant financial relationships.

American Roentgen Ray Society (ARRS) 2016 Annual Meeting: Abstract 3569. Presented April 18, 2016.

Follow Damian McNamara on Twitter: @MedReporter

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