American College of Radiology

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October 16, 2017

Don’t recommend ultrasound for incidental thyroid nodules found on CT, MRI or non-thyroid-focused neck ultrasound in low-risk patients unless the nodule meets age-based size criteria or has suspicious features.

Imaging of the neck performed to evaluate non-thyroid-related conditions commonly reveals thyroid nodules. Most are not malignant. Even if malignant, they are likely to have indolent behavior. Fine needle aspiration often fails to definitively characterize a lesion as benign owing to the limitations of cytologic evaluation. Consequently, some patients with incidentally-discovered benign nodules undergo unnecessary serial ultrasound imaging and/or surgery. Accordingly, patients without clinical risk factors* who are found to have asymptomatic, incidental, nonsuspicious thyroid nodules on cross-sectional imaging (CT, MRI or non-thyroid ultrasound of the neck) should be referred for diagnostic thyroid ultrasound only if they meet the following criteria:

(1) < 35 years of age with normal life expectancy and nodule ≥ 1 cm.
(2) ≥ 35 years of age with normal life expectancy and nodule ≥ 1.5 cm.

Two published studies reported that the percentage of nodules referred for ultrasound would be reduced by 35–46% using the proposed algorithm.

Suspicious features on CT, MRI or US include signs of local invasion, and the presence of abnormal lymph nodes (enlarged nodes, nodes with cystic change, calcification, or increased enhancement).

i. Size criteria for enlarged lymph nodes:
1. ≥1.5 cm in short axis for jugulodigastric nodes
2. ≥1 cm for other nodes

ii. Lymph nodes in levels IV and VI are especially suspicious for thyroid cancer metastases.

* Clinical risk factors: Patients with history of head, neck or chest radiation, family history of thyroid cancer, or diseases that increase the risk of thyroid cancer should be further evaluated regardless of nodule size.

These items are provided solely for informational purposes and are not intended as a substitute for consultation with a medical professional. Patients with any specific questions about the items on this list or their individual situation should consult their physician.

How The List Was Created

(1-5) The American College of Radiology (ACR) initially solicited expert opinion from physician leaders with its Board of Chancellors. A working group was then formed to further identify common clinical scenarios in which imaging may be misused and should be reconsidered. Members of the group included the physician chairs or vice chairs of seven ACR commissions such as Quality and Safety, Appropriateness Criteria and Metrics. An initial list of topics was narrowed down based on the highest potential for improvement, representing a broad range of tests and the availability of strong guidelines. Members then researched specific recommendations and evidentiary statements based on their expertise. Recommendations that were too general or were well covered by other existing measures and initiatives were eliminated to identify the final five things list.

(6-10) The Choosing Wisely initiative was presented to the organization’s physician leaders at a Board of Chancellors meeting and a working group selected five initial low-value imaging targets for reduced utilization. The second set of targets was created by the following working group, with the goals of minimizing unnecessary imaging and biopsy generated by discovery of incidental findings, improving patient safety through reduced radiation exposure, and reducing unnecessary consultations based on imaging findings.

  • Pamela T. Johnson, MD, Chair, Choosing Wisely Recommendations
  • Jacqueline A. Bello, MD, FACR, Chair of Commission on Quality and Safety
  • Mythreyi B. Chatfield, PhD, Executive Vice President for Quality and Safety
  • Jonathan Flug, MD, MBA, Quality Management Committee
  • Jenny K. Hoang, MBBS, lead author on ACR White Paper for Managing Incidental Thyroid Nodules
  • Alec J. Megibow, MD, MPH, FACR, Committee on Economics – Body Imaging Commission
  • Pari V. Pandharipande, MD, MPH, Chair of Committee on Incidental Findings
  • Saurabh Rohatgi, MD, Committee on Quality Experience – Commission on Patient and Family Centered Care

Research: For the topics related to incidental findings on imaging exams, the American College of Radiology has created evidence-based white papers to provide guidance to practicing radiologists on making management recommendations. The white paper publications and additional relevant literature serve as the evidence supporting those recommendations. For the remaining recommendations pertaining to body CT protocol design, published literature was reviewed to define acceptable indications for multiphase protocols.

ACR’s disclosure and conflict of interest policy can be found at


Vaccarella S, Franceschi S, Bray F, Wild CP, Plummer M, Dal Maso L. Worldwide Thyroid-Cancer Epidemic? The Increasing Impact of Overdiagnosis. N Engl J Med. 2016 Aug 18;375(7):614-7. doi: 10.1056/NEJMp1604412. PubMed PMID: 27532827.

Hoang JK, Langer JE, Middleton WD, Wu CC, Hammers LW, Cronan JJ, Tessler FN, Grant EG, Berland LL. Managing incidental thyroid nodules detected on imaging: white paper of the ACR Incidental Thyroid Findings Committee. J Am Coll Radiol. 2015 Feb;12(2):143-50. doi: 10.1016/j.jacr.2014.09.038. Epub 2014 Nov 1. PubMed PMID: 25456025.

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Tanpitukpongse TP, Grady AT, Sosa JA, Eastwood JD, Choudhury KR, Hoang JK. Incidental thyroid nodules on CT or MRI: Discordance between what we report and what receives workup. AJR Am J Roentgenol. 2015 Dec;205(6):1281-1287. doi: 10.2214/AJR.15.14929. PubMed PMID: 26587935.

Bahl M, Sosa JA, Eastwood JD, Hobbs HA, Nelson RC, Hoang JK. Using the 3-tiered system for categorizing workup of incidental thyroid nodules detected on CT, MRI, or PET/CT: how many cancers would be missed? Thyroid. 2014 Dec;24(12):1772-8. doi: 10.1089/thy.2014.0066. PubMed PMID: 25203387.

Hobbs HA, Bahl M, Nelson RC, Kranz PG, Esclamado RM, Wnuk NM, Hoang JK. Journal Club: incidental thyroid nodules detected at imaging: can diagnostic workup be reduced by use of the Society of Radiologists in Ultrasound recommendations and the three-tiered system? AJR Am J Roentgenol. 2014 Jan;202(1):18-24.

Nguyen XV, Choudhury KR, Eastwood JD, Lyman GH, Esclamado RM, Werner JD, Hoang JK. Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for work-up of nodules. AJNR Am J Neuroradiol. 2013 Sep;34(9):1812-7. doi: 10.3174/ajnr.A3487. Epub 2013 Apr 4.