Original article
Health services research and policy
ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee

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Abstract

Thyroid nodules are a frequent finding on neck sonography. Most nodules are benign; therefore, many nodules are biopsied to identify the small number that are malignant or require surgery for a definitive diagnosis. Since 2009, many professional societies and investigators have proposed ultrasound-based risk stratification systems to identify nodules that warrant biopsy or sonographic follow-up. Because some of these systems were founded on the BI-RADS® classification that is widely used in breast imaging, their authors chose to apply the acronym TI-RADS, for Thyroid Imaging, Reporting and Data System. In 2012, the ACR convened committees to (1) provide recommendations for reporting incidental thyroid nodules, (2) develop a set of standard terms (lexicon) for ultrasound reporting, and (3) propose a TI-RADS on the basis of the lexicon. The committees published the results of the first two efforts in 2015. In this article, the authors present the ACR TI-RADS Committee’s recommendations, which provide guidance regarding management of thyroid nodules on the basis of their ultrasound appearance. The authors also describe the committee’s future directions.

Introduction

Thyroid nodules are exceedingly common, with a reported prevalence of up to 68% in adults on high-resolution ultrasound [1]. Currently, fine-needle aspiration (FNA) is the most effective, practical test to determine whether a nodule is malignant or may require surgery to reach a definitive diagnosis [2]. However, most nodules are benign, and even malignant nodules, particularly ones smaller than 1 cm, frequently exhibit indolent or nonaggressive behavior 3, 4, 5. Therefore, not all detected nodules require FNA and/or surgery.

Despite a rapid increase in the reported incidence of papillary thyroid cancer that resulted from screening thyroid sonography in asymptomatic patients in South Korea, mortality has remained extremely low [6]. In the United States, overdiagnosis of thyroid cancer, defined as “diagnosis of thyroid tumors that would not, if left alone, result in symptoms or death” accounted for 70% to 80% of thyroid cancer cases in women and 45% of cases in men between 2003 and 2007 [7].

Therefore, a reliable, noninvasive method to identify which nodules warrant FNA on the basis of a reasonable likelihood of biologically significant malignancy would be highly desirable. In 2015, committees convened by the ACR published white papers that presented an approach to incidental thyroid nodules and proposed standard terminology (lexicon) for ultrasound reporting 8, 9. The purpose of the present white paper is to present our system for risk stratification, which is designed to identify most clinically significant malignancies while reducing the number of biopsies performed on benign nodules.

Section snippets

Project Rationale and Consensus Process

Several professional societies and groups of investigators have proposed methods to guide ultrasound practitioners in recommending FNA on the basis of ultrasound features 10, 11, 12, 13, 14, 15, 16, 17, 18. Some of these systems were termed TI-RADS (Thyroid Imaging, Reporting and Data System) because they were modeled on the ACR’s BI-RADS®, which has been widely accepted in breast imaging. Other societies, such as the American Thyroid Association (ATA), have taken a slightly different,

Overview of ACR TI-RADS

The ultrasound features in the ACR TI-RADS are categorized as benign, minimally suspicious, moderately suspicious, or highly suspicious for malignancy. Points are given for all the ultrasound features in a nodule, with more suspicious features being awarded additional points. Figure 1 presents these features arranged per the five lexicon categories [8]. When assessing a nodule, the reader selects one feature from each of the first four categories and all the features that apply from the final

Structure

To make the system easy to understand and apply, the ACR TI-RADS does not include subcategories, nor does it include a TR0 category to indicate a normal thyroid gland. The ACR TI-RADS also lends itself to implementation as templates in voice recognition reporting or computerized decision support systems. The committee decided against the pattern-based approach used by the ATA on the basis of the results of a study by Yoon et al [25], which showed that the ATA guidelines were unable to classify

ACR TI-RADS Feature Categories

In this section, we elaborate on the five groups of ultrasound findings, ACR TI-RADS levels, and size thresholds. Readers are encouraged to refer to the lexicon white paper for detailed descriptions of all the categories and features [8]. As well, any history of prior FNA or ethanol ablation should be sought, as these procedures may lead to a suspicious appearance at follow-up ultrasound [31].

Papillary Thyroid Microcarcinomas

The ACR TI-RADS is concordant with other guidelines in recommending against routine biopsy of nodules smaller than 1 cm, even if they are highly suspicious. However, because some thyroid specialists advocate active surveillance, ablation, or lobectomy for papillary microcarcinomas, biopsy of 5- to 9-mm TR5 nodules may be appropriate under certain circumstances 24, 55, 56, 57. The determination to perform FNA will involve shared decision making between the referring physician and the patient.

Measurement and Documentation

Accurate sizing of thyroid nodules is critical, as the maximum dimension determines whether a given lesion should be biopsied or followed. Although some interobserver discrepancy is inevitable because of variable conspicuity, consistent technique improves measurement accuracy and reproducibility.

Nodules should be measured in three axes: (1) maximum dimension on an axial image, (2) maximum dimension perpendicular to the previous measurement on the same image, and (3) maximum longitudinal

Future Directions

The committee believes that the ACR TI-RADS meets our stated goals, although acknowledging the limitations of our additive approach, which does not fully account for the possibility that the risk conferred by a given ultrasound feature may vary depending on what other features are present in a nodule. As well, several committee members have embarked on a parallel project in which interobserver variability of ultrasound feature assignment will be measured. We plan to revise the ACR TI-RADS

Take-Home Points

  • The goal of this project is to define a risk stratification system for thyroid nodules (ACR TI-RADS) to guide decisions regarding FNA and follow-up.

  • The ACR TI-RADS chart allows practitioners to assign points to nodules based on ultrasound features from a standardized lexicon that lends itself to structured reporting.

  • The features that form the basis of this system will be assessed for inter-observer variability in a parallel project.

Acknowledgments

The authors thank Dr Herbert Chen, chair of the Department of Surgery at the University of Alabama at Birmingham, for reviewing the manuscript. We also are grateful to Dr Xuan V. Nguyen of Ohio State University for performing the SEER data analysis.

References (67)

  • S. Guth et al.

    Very high prevalence of thyroid nodules detected by high frequency (13 MHz) ultrasound examination

    Eur J Clin Invest

    (2009)
  • N. Singh Ospina et al.

    Diagnostic accuracy of ultrasound-guided fine needle aspiration biopsy for thyroid malignancy: systematic review and meta-analysis

    Endocrine

    (2016)
  • R. Smith-Bindman et al.

    Risk of thyroid cancer based on thyroid ultrasound imaging characteristics: results of a population-based study

    JAMA Intern Med

    (2013)
  • Y. Ito et al.

    An observation trial without surgical treatment in patients with papillary microcarcinoma of the thyroid

    Thyroid

    (2003)
  • L. Davies et al.

    Current thyroid cancer trends in the United States

    JAMA Otolaryngol Head Neck Surg

    (2014)
  • H.S. Ahn et al.

    Korea’s thyroid-cancer “epidemic”—screening and overdiagnosis

    N Engl J Med

    (2014)
  • S. Vaccarella et al.

    Dal Maso L. Worldwide thyroid-cancer epidemic? The increasing impact of overdiagnosis

    N Engl J Med

    (2016)
  • M.C. Frates et al.

    Management of thyroid nodules detected at US: Society of Radiologists in Ultrasound consensus conference statement

    Radiology

    (2005)
  • E. Horvath et al.

    An ultrasonogram reporting system for thyroid nodules stratifying cancer risk for clinical management

    J Clin Endocrinol Metab

    (2009)
  • J.Y. Kwak et al.

    Thyroid imaging reporting and data system for US features of nodules: a step in establishing better stratification of cancer risk

    Radiology

    (2011)
  • D.G. Na et al.

    Thyroid imaging reporting and data system risk stratification of thyroid nodules: categorization based on solidity and echogenicity

    Thyroid

    (2016)
  • J.Y. Park et al.

    A proposal for a thyroid imaging reporting and data system for ultrasound features of thyroid carcinoma

    Thyroid

    (2009)
  • H. Seo et al.

    Ultrasound-based risk stratification for malignancy in thyroid nodules: a four-tier categorization system

    Eur Radiol

    (2015)
  • G. Russ

    Risk stratification of thyroid nodules on ultrasonography with the French TI-RADS: description and reflections

    Ultrasonography

    (2016)
  • J.H. Shin et al.

    Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

    Korean J Radiol

    (2016)
  • A.R. Zayadeen et al.

    Retrospective evaluation of ultrasound features of thyroid nodules to assess malignancy risk: a step toward TIRADS

    AJR Am J Roentgenol

    (2016)
  • B.R. Haugen et al.

    2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

    Thyroid

    (2016)
  • F. Magri et al.

    The role of elastography in thyroid ultrasonography

    Curr Opin Endocrinol Diabetes Obes

    (2016)
  • Y. Ito et al.

    Nonoperative management of low-risk differentiated thyroid carcinoma

    Curr Opin Oncol

    (2015)
  • J.H. Yoon et al.

    Malignancy risk stratification of thyroid nodules: comparison between the Thyroid Imaging Reporting and Data System and the 2014 American Thyroid Association management guidelines

    Radiology

    (2016)
  • A. Machens et al.

    The prognostic value of primary tumor size in papillary and follicular thyroid carcinoma

    Cancer

    (2005)
  • M.S. Deveci et al.

    Concordance between thyroid nodule sizes measured by ultrasound and gross pathology examination: effect on patient management

    Diagn Cytopathol

    (2007)
  • Middleton WD, Teefey SA, Reading C, et al. Multi-institutional analysis of thyroid nodule risk stratification using the...
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    Dr Berland received personal fees from Nuance Communications during the conduct of the study. Dr Beland has received personal fees from Hitachi Aloka America outside the submitted work. All other authors have no conflicts of interest related to the material discussed in this article.

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