Original article
Managing Incidental Thyroid Nodules Detected on Imaging: White Paper of the ACR Incidental Thyroid Findings Committee

https://doi.org/10.1016/j.jacr.2014.09.038Get rights and content

Abstract

The incidental thyroid nodule (ITN) is one of the most common incidental findings on imaging studies that include the neck. An ITN is defined as a nodule not previously detected or suspected clinically, but identified by an imaging study. The workup of ITNs has led to increased costs from additional procedures, and in some cases, to increased risk to the patient because physicians are naturally concerned about the risk of malignancy and a delayed cancer diagnosis. However, the majority of ITNs are benign, and small, incidental thyroid malignancies typically have indolent behavior. The ACR formed the Incidental Thyroid Findings Committee to derive a practical approach to managing ITNs on CT, MRI, nuclear medicine, and ultrasound studies. This white paper describes consensus recommendations representing this committee’s review of the literature and their practice experience.

Section snippets

Foreword

This white paper is not meant to comprehensively review the interpretation and management of thyroid nodules, but to provide general guidance for managing incidentally discovered thyroid nodules (ITNs). Individual care will, of course, vary depending on each patient’s specific circumstances, the clinical environment and available resources, and the judgment of the practitioner. In addition, the term “guidelines” has intentionally not been used in this white paper, to avoid the implication that

Project Objectives

The objective of this project was to develop medically appropriate approaches to managing ITNs detected on a variety of imaging modalities. Benefits anticipated from this effort include the following:

  • Distinguishing between ITNs that do versus do not require dedicated thyroid ultrasound;

  • Reducing the downstream risks and costs by reducing the likelihood that an ITN will lead to a dedicated thyroid ultrasound and potential consequences following FNA;

  • Achieving greater consistency in recognizing,

Project History and Consensus Process

The Incidental Thyroid Findings Committee (hereafter the Committee) was formed under the auspices of the ACR in 2013. The intent was to develop guidance analogous to the white papers produced by the ACR Incidental Finding Committee on abdominal and pelvic incidental findings on CT and MRI 6, 7.

The Committee participants were recruited from members of the ACR and included academic and private practice radiologists with subspecialties in sonography, abdominal imaging, neuroradiology, and chest

Elements, Recommendations, and Flowcharts

In the flowcharts within this white paper, the algorithms use yellow boxes for steps that involve data that affect management; green boxes to represent action steps; and red boxes to indicate that no further action is required. Radiologists are unlikely to be aware of all relevant clinical factors at the time an ITN is discovered. However, these recommendations do not apply to patients with increased risk for thyroid carcinoma, those who may be symptomatic from thyroid disease, or pediatric

Prevalence of ITNs and Risk of Malignancy

Thyroid nodules are very common in the adult population. A large autopsy study published in 1955 found that 50% of patients with no clinical history of thyroid disease had thyroid nodules, and the majority were multiple [8]. Like autopsy, imaging can reveal subclinical thyroid nodules. With increased use of imaging for screening, diagnosis, and treatment response evaluation over the past three decades, ITNs have become a common finding that may be recommended for workup. ITNs are seen in

Implications of Imaging and Clinical Features

An ITN can be detected on CT or MRI scans that cover the lower neck or upper mediastinum. CT of the chest is responsible for the majority of ITNs [5]. These scans can be performed with or without intravenous contrast, but thyroid nodules can readily be seen even without contrast, because normal thyroid tissue has intrinsic high attenuation on CT, and a lower T2 signal on MRI.

CT and MRI examinations have no reliable signs to indicate that a thyroid nodule is benign or malignant. The reason is at

Implications of Imaging and Clinical Features

The main source of ITNs on nuclear medicine imaging is 18FDG-PET scans. Focal increased metabolic activity on 18FDG-PET studies is very indicative of malignancy regardless of the sonographic findings on subsequent workup. Two studies found that metabolically active nodules without any suspicious sonographic findings still had a relatively high malignancy rate of 11%-13% 38, 39. Other important factors to consider in workup of patients with a metabolically active ITN are comorbidities and

Implications of Imaging and Clinical Features

ITNs are commonly detected during the course of thyroid ultrasound examinations performed for symptoms or a palpable nodule. Therefore, such nodules do not constitute incidental findings, and these recommendations do not apply 31, 32, 43. However, the situation differs when an ITN is detected during sonography of extra-thyroidal structures, such as the carotid arteries, salivary glands, cervical lymph nodes, parathyroid glands, and miscellaneous neck masses. Documentation of findings for the

Future Committee Objectives

The Committee hopes that these recommendations will become widely applied. The ACR is developing methods to make these recommendations accessible electronically. The Committee recommends that the concepts, terminology, and parameters discussed in this article become the basis for future research to advance scientific evidence regarding incidental findings.

Take-Home Points

  • In patients age <35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thyroid ultrasound if the nodule is ≥1 cm and has no suspicious imaging features, and if the patient has normal life expectancy.

  • In patients age ≥35 years with an ITN detected on CT, MRI, or extrathyroidal ultrasound, the Committee recommends further evaluation with dedicated thryoid ultrasound if the nodule is ≥1.5 cm and has no suspicious imaging

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