Thyroid Nodules: Is It Time to Turn Off the US Machines? 1 John J. Cronan, MD T he authors of the article “Benign and Malignant Thyroid Nodules: US Differentiation—Multicenter Retro- spective Study” in this issue of Radiology (1) present a well-organized multicenter study evaluating ultrasonographic (US) findings associated with benign and malig- nant thyroid nodules. I review one to two manuscripts a month from groups throughout the world, looking to establish more specific criteria and ultimately de- fine histologic specificity in distinguishing benign from malignant nodules. These US series are all retrospective evaluations of thyroid nodules that emphasize the over- lap between benign and malignant ap- pearance, as well as the need to perform fine needle aspiration (FNA) if a precise diagnosis is the goal. The degree of overlap in the US ap- pearance of benign and malignant nod- ules is great enough that a cytologic FNA sample is usually necessary to make the diagnosis of a benign or malig- nant nodule. The Society of Radiologists in Ultrasound consensus panel acknowl- edged that, “[a]lthough there are cer- tain trends in the US distinction of be- nign and malignant thyroid nodules, there is also overlap in their appear- ances. Because of the inconsistent pre- dictive value of US features, most agree that FNA and cytopathologic evaluation of a thyroid nodule are usually required before a patient undergoes surgical re- section for a possible thyroid malig- nancy” (2). Why Assess Thyroid Nodules? The article by Moon et al (1) continues the struggle to categorize nodules as benign or malignant with US criteria. Whether this will ever be sufficiently practical to avoid performing biopsy of certain nodules because they are clearly benign or malignant is still debatable. However, the article provokes a more important question that has percolated into the US and endocrinology worlds. Should we be searching for nonpalpable thyroid nodules with US and what are we accomplishing by doing so? What is the motivation? Because our technology permits detection of 2–3-mm nodules, should we maintain the chase? I fear we have accepted a sisyphean task in mak- ing all thyroid nodules a focus of con- cern. Is it time to reassess our goals in the detection and characterization of thyroid nodules? Discuss this article online at www.rsna.org/radiology/discuss. A Normal Finding The prevalence of thyroid nodules in the U.S. population is dependent on the tool used for interrogation of the thyroid. With simple palpation, 4%–7% of the population has a thyroid nodule. At au- topsy, 50%– 60% of the population is found to have a thyroid nodule. How- ever, the reservoir of clinically silent im- palpable nodules is truly expanded when high-resolution US is utilized for thyroid evaluation. Up to 67% of the population evaluated with US will have an incidental thyroid nodule (3). Con- servatively, if 50% of the U.S. popula- tion (approximately 300 million) has a nodule, we are dealing with a potential reservoir of 150 million Americans Published online 10.1148/radiol.2473072233 Radiology 2008; 247:602– 604 1 From the Department of Diagnostic Imaging, Rhode Is- land Hospital, the Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903. Re- ceived December 31, 2007; final version accepted Janu- ary 22, 2008. Address correspondence to the author (e-mail: jcronan@lifespan.org ). Author stated no financial relationship to disclose. See also the article by Moon et al in this issue.  RSNA, 2008 REVIEWS AND COMMENTARY  EDITORIAL 602 Radiology: Volume 247: Number 3—June 2008 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.