A new and simple risk-stratification system based on thyroid-nodule features seen on ultrasound can determine if a nodule needs a fine-needle aspiration (FNA) biopsy to detect potential cancer or not, thereby helping avoid unnecessary biopsies, researchers report.
Franklin N Tessler, MD, from the University of Birmingham, Alabama, and colleagues have presented their simple scheme, termed the American College of Radiology (ACR) Thyroid Imaging, Reporting, and Data System (TI-RADS) in a paper published in the Journal of the American College of Radiology (2017;14:587-595).
ACR TI-RADS assigns points to thyroid nodules based on five features —composition, echogenicity, shape, margin, and echogenic focus — and the nodules are then classed as benign, not suspicious, or mildly, moderately, or highly suspicious.
Benign nodules or those that are not suspicious need not be biopsied, whereas other nodules may need a biopsy or repeat ultrasound, depending on size.
ACR TI-RADS “is designed to identify most clinically significant malignancies while reducing the number of biopsies performed on benign nodules,” according to the researchers.
Also, “we wanted to produce a set of guidelines that we felt would be easier to apply than some of the others,” as some radiologists, endocrinologists, and other clinicians may not perform many thyroid ultrasounds, Dr Tessler told Medscape Medical News.
Avoid Needless Biopsy, Still Spot Important Cancer
As most thyroid nodules are benign, it is important to be able to identify suspicious ones and perform fewer biopsies on benign nodules.
Investigators in Chile, France, and Korea have developed risk-stratification systems based on thyroid nodule features on ultrasound, which they termed TI-RADS, modelled after ACR’s BI-RADS, which has been widely accepted in breast imaging, said Dr Tessler.
In addition, the Society of Radiologists in Ultrasound has published guidelines, and the American Thyroid Association (ATA) uses a pattern-oriented approach.
“The plethora, complexity, and lack of congruence of these systems has limited their adoption by the ultrasound community,” according to the researchers.
“The ACR TI-RADS is designed to balance the benefit of identifying clinically important cancers against the risk and cost of subjecting patients with benign nodules or indolent cancers to biopsy and treatment.”
In 2015, ACR committees published recommendations for reporting incidental thyroid nodules (J Am Coll Radiol. 2015;12:143-150) and provided a set of standard terms (lexicon) for ultrasound reporting (J Am Coll Radiol. 2015;12:1272-1279).
Building on this, the current report presents a simplified risk-stratification system.
To make it easy to apply, it does not include subcategories.
Moreover, it does not use a pattern-based approach, as a study by Yoon and colleagues (Radiology. 2016;278:917-924) showed that ATA guidelines were unable to classify 3.4% of 1293 nodules, of which 18.2% were malignant, and it is not practical to provide patterns for every potential combination of features.
Five Appearance Categories, Five Risk Categories
Instead, using ACR TI-RADS thyroid nodules are awarded points based on their appearance on ultrasound in five categories:
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Composition: From 0 points for cystic to 2 points for solid
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Echogenicity: From 0 points for anechoic to 3 points for very hypoechoic
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Shape: 0 points for wider-than-tall and 3 points for taller-than-wide
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Margin: From 0 points for smooth to 3 points for extra-thyroidal extension
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Echogenic foci: From 0 points for none to 3 points for punctate echogenic foci
Based on their total points, nodules are then classed into five categories of suspicion for cancer:
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0 points, benign: No fine needle aspiration (FNA)
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2 points, not suspicious: No FNA
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3 points, mildly suspicious: FNA if ≥ 2.5 cm; follow if ≥ 1.5 cm
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4 to 6 points, moderately suspicious: FNA if ≥ 1.5 cm; follow if ≥ 1 cm
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≥ 7 points, highly suspicious: FNA if ≥ 1 cm; follow if ≥ 0.5 cm
For nodules that are too small to meet the criteria for FNA, follow-up imaging should be done at 1, 3, and 5 years for moderately suspicious nodules, and possibly at the same times for mildly suspicious nodules, but it should be done annually for up to 5 years for highly suspicious nodules.
Biopsies should be done on no more than “two nodules with the most suspicious appearance based on point totals . . . even if they are not the largest,” because performing a biopsy on “three or more nodules is poorly tolerated by patients and increases cost with little or no benefit and some added risk,” Dr Tessler and colleagues note.
Watchful Waiting for Low-Risk Thyroid Cancer . . .
In Korea, a sharp rise in the diagnosis and treatment of thyroid malignancies did not lead to improved long-term outcomes, so “diagnosing every thyroid malignancy should not be our goal,” they write.
“Like other professional societies, we recommend biopsy of high-suspicion nodules only if they are 1 cm or larger. As well, we advocate biopsy of nodules that have a low risk for malignancy only when they measure 2.5 cm or more.”
Performing the recommended follow-up ultrasounds should detect any significant malignancies and is consistent with the trend toward active surveillance (“watchful waiting”) for low-risk thyroid cancer.
Further research over a longer time is needed to determine how well this ultrasound-based risk-stratification system “finds the nodules that are going to make a difference to the patient,” Dr Tessler said.
The ACR recently awarded a $100,000 grant to Jenny K Hoang, MBBS, at Duke University School of Medicine, in Durham, North Carolina, to set up a registry for thyroid nodules, which will provide insight into long-term patient outcomes, he said.
The authors of the three studies have reported no relevant financial relationships.
J Am Coll Radiol. 2017;14:587-595. Full text
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