Published ahead of print on January 14, 2010
doi: 10.3174/ajnr.A1934

American Journal of Neuroradiology 31:E30, February 2010
© 2010 American Society of Neuroradiology

L.E. Ginsberg^a, G.I. Clayman^b, B.S. Edeiken-Monroe^c, E. Rohren^d andS.I. Sherman^e
aProfessor of Radiology and Head and Neck Surgery Diagnostic Radiology
^bA.J. Ballantyne Professor of Head and Neck Surgery Co-Director Thyroid Surgery Program
^cDirector of Head and Neck Ultrasound
^dAssociate Professor of Radiology Director of PET/CT Director ad interim Clinical Nuclear Medicine
^eProfessor and Chair Department of Endocrine Neoplasia and Hormonal Disorders University of Texas MD Anderson Cancer Center Houston, Texas

We at MD Anderson Cancer Center are concerned by the suggestions made by Eloy et al¹ in the August 2009 issue of the American Journal of Neuroradiology regarding fluorodeoxyglucose (FDG) activity in the thyroid gland in patients undergoing positron-emission tomography (PET/CT) for nonthyroid malignancy. It is already well known that incidental identification of papillary thyroid cancer is common, as is the fact that the magnitude of uptakeas measured by the standard uptake value cannot readily differentiate benign and malignant etiologies. In these matters, the article of Eloy et al breaks no new ground.

However, the recommendation that all such patients even undergo hemithyroidectomy causes us concern for a number of reasons. First, although we agree that there is always the potential for an occult thyroid malignancy to be high-grade, most are quite indolent. Second, it seems that the recommendation for surgery, even if findings of sonography-guided fine needle aspiration (USG-FNA) are negative, suggests an unacceptable risk of sampling error and false-negative biopsies in direct contradiction ofestablished consensus guidelines for the management of thyroid nodules.^2,3Finally, before any consideration of surgery, one must balance the risks and benefits of that surgery in light of the patient’s other potentially more life-threatening malignancy that brought them to be imaged by PET/CT in the first place.

In addition to the usual complications of any surgery, hemithyroidectomy carries its own risk of vocal cord paralysis; completion of thyroidectomy entails a second surgery, which may result in hypoparathyroidism and the need for lifetime thyroid hormone replacement.

We believe that an USG-FNA is a very reasonable approach to such lesions, with surgery being performed only in the eventthat malignancy is either confirmed or suspected cytologically,⁴ and that such surgery makes oncologic sense based on a patient’s overall circumstance. Measurement of serum thyroid stimulating hormone in such patients is appropriate as a screening procedure for an autonomously hyperfunctioning adenoma.

To recommend even hemithyroidectomy for any cancer patients with an incidental FDG-avid thyroid lesion, while ignoring anegative USG-FNA, seems unwarranted and potentially harmful, particularly if 72% of the resected specimens will be benign.

References

1. Eloy JA, Brett EM, Fatterpekar GM, et al. The significance and management of incidental [¹⁸F]fluorodeoxyglucose–positron-emission tomography uptake in the thyroid gland in patients with cancer. AJNR Am J Neuroradiol2009;30:1431–34[Abstract/Free Full Text]
2. Cooper DS, Doherty GM, Haugen BR, et al. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2006;16:109–42[Medline]
3. Sherman SI. National Comprehensive Cancer Network. NCCN presents updates to NCCN guidelines for thyroid carcinoma, 2009a. http://www.nccn.org/about/news/newsinfo.asp?NewsID=209. Accessed September 11, 2009
4. Layfield LJ, Abrams J, Cochand-Priollet B, et al. Post-thyroid FNA testing and treatment options: a synopsis of the National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference. Diagn Cytopathol2008;36:442–48[CrossRef][Medline]

Reply

Published ahead of print on January 14, 2010
doi: 10.3174/ajnr.A1998

American Journal of Neuroradiology 31:E31, February 2010
© 2010 American Society of Neuroradiology

E.M. Genden^a
aChairman—Department of Otolaryngology Mount Sinai Medical Center New York, New York

The American Thyroid Association guidelines for the management of patients with thyroid nodules¹ outlines the role of sonography and fine-needle aspiration for the evaluation of thyroid nodules. Our work and the work of others^2–4 suggest that fluorodeoxyglucose–positron-emission tomography (FDG-PET) positivity is associated with a significant risk of malignancy, not unlike the cytologic reading of “indeterminate cytology,” which, according to the task force (R9, recommendation B), states that a “lobectomy or total thyroidectomy should be considered.”¹ We support the work of the American Thyroid Association and believe that FDG-PET positivity simply represents an adjunct to sonography and cytology for the risk assessment of a patient with a thyroid nodule. We do not advocate thyroidectomy for patients with benign cytology and retract any implication of such; however, we do inform patients of the data on FDG-PET positivity—after all, the false-negative rate for fine-needleaspiration of thyroid nodules is higher than the false-positive rate. The American Thyroid Association recommends that a lobectomy or total thyroidectomy be considered for indeterminate cytology, which is associated with a 5%–10% risk of malignancy. Do we feel comfortable withholding surgical intervention when FDG-PET positivity is associated with a 25%–50% risk of malignancy?

References

1. Cooper DS, Doherty GM, Haugen BR, et al. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2006;16:109–42[Medline]
2. Choi JY, Lee KS, Kim HJ, et al. Focal thyroid lesions incidentally identified by integrated 18F-FDG PET/CT: clinical significance and improved characterization. J Nucl Med 2006;47:609–15[Abstract/Free Full Text]
3. Kang KW, Kim SK, Kang HS, et al. Prevalence and risk of cancer of focal thyroid incidentaloma identified by 18F-fluorodeoxyglucose positron emission tomography for metastasis evaluation and cancer screening in healthy subjects. J Clin Endocrinol Metab 2003;88:4100–04[Abstract/Free Full Text]
4. Chen YK, Ding HJ, Chen KT, et al. Prevalence and risk of cancer of focal thyroid incidentaloma identified by 18F-fluorodeoxyglucose positron emission tomography for cancer screening in healthy subjects. Anticancer Res 2005;25:1421–6[Abstract/Free Full Text]