Endocrinol Metab.  2015 Mar;30(1):71-77. 10.3803/EnM.2015.30.1.71.

Risk of Malignancy in Thyroid Incidentalomas Identified by Fluorodeoxyglucose-Positron Emission Tomography

Affiliations
  • 1Division of Endocrinology and Metabolism, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea. byby815@schmc.ac.kr
  • 2Department of Nuclear Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.

Abstract

BACKGROUND
Thyroid incidentalomas detected by 2-deoxy-2-18F-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) have been reported in 1% to 4% of the population, with a risk of malignancy of 27.8% to 74%. We performed a retrospective review of FDG-avid thyroid incidentalomas in cancer screening subjects and patients with nonthyroid cancer. The risk of malignancy in thyroid incidentaloma and its association with the maximal standardized uptake value (SUVmax) in 18F-FDG PET/CT were evaluated to define the predictor variables in assessing risk of malignancy.
METHODS
A total of 2,584 subjects underwent 18F-FDG PET/CT for metastatic evaluation or cancer screening from January 2005 to January 2010. Among them, 36 subjects with FDG-avid thyroid incidentalomas underwent further diagnostic evaluation (thyroid ultrasonography-guided fine needle aspiration cytology [FNAC] or surgical resection). We retrospectively reviewed the database of these subjects.
RESULTS
Of the 2,584 subjects who underwent 18F-FDG PET/CT (319 for cancer screening and 2,265 for metastatic evaluation), 52 (2.0%) were identified as having FDG-avid thyroid incidentaloma and cytologic diagnosis was obtained by FNAC in 36 subjects. Of the subjects, 15 were proven to have malignant disease: 13 by FNAC and two by surgical resection. The positive predictive value of malignancy in FDG-avid thyroid incidentaloma was 41.7%. Median SUVmax was higher in malignancy than in benign lesions (4.7 [interquartile range (IQR), 3.4 to 6.0] vs. 2.8 [IQR, 2.6 to 4.0], P=0.001).
CONCLUSION
Thyroid incidentalomas found on 18F-FDG PET/CT have a high risk of malignancy, with a positive predictive value of 41.7%. FDG-avid thyroid incidentalomas with higher SUVmax tended to be malignant.

Keyword

Thyroid gland; Incidental findings; Fluorodeoxyglucose F18; Positron-emission tomography; Thyroid neoplasms; Prevalence

MeSH Terms

Biopsy, Fine-Needle
Diagnosis
Early Detection of Cancer
Electrons
Fluorodeoxyglucose F18
Humans
Incidental Findings
Positron-Emission Tomography
Positron-Emission Tomography and Computed Tomography
Prevalence
Retrospective Studies
Thyroid Gland*
Thyroid Neoplasms
Fluorodeoxyglucose F18

Figure

  • Fig. 1 Selection of patients from those who underwent 2-deoxy-2-18F-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) for cancer screening and metastatic evaluation was based on the presence of focal FDG-avid thyroid incidentaloma. FNAB, fine needle aspiration biopsy; US, ultrasonography.

  • Fig. 2 A 60-year-old man with underlying sigmoid colon cancer. (A) A focal fluorodeoxyglucose-avid lesion with calcification was incidentally detected in the right lobe of the thyroid (posterior-anterior view). (B) Fusion axial positron emission tomography/computed tomography image showing a hypermetabolic lesion and calcification in the right lobe of the thyroid gland (maximal standardized uptake value=2.6).


Reference

1. Hegedus L. Clinical practice: the thyroid nodule. N Engl J Med. 2004; 351:1764–1771.
2. Lin JD, Chao TC, Huang BY, Chen ST, Chang HY, Hsueh C. Thyroid cancer in the thyroid nodules evaluated by ultrasonography and fine-needle aspiration cytology. Thyroid. 2005; 15:708–717.
3. Nam-Goong IS, Kim HY, Gong G, Lee HK, Hong SJ, Kim WB, Shong YK. Ultrasonography-guided fine-needle aspiration of thyroid incidentaloma: correlation with pathological findings. Clin Endocrinol (Oxf). 2004; 60:21–28.
4. Kim H, Kim SJ, Kim IJ, Kim K. Thyroid incidentalomas on FDG PET/CT in patients with non-thyroid cancer: a large retrospective monocentric study. Onkologie. 2013; 36:260–264.
5. Shie P, Cardarelli R, Sprawls K, Fulda KG, Taur A. Systematic review: prevalence of malignant incidental thyroid nodules identified on fluorine-18 fluorodeoxyglucose positron emission tomography. Nucl Med Commun. 2009; 30:742–748.
6. Cohen MS, Arslan N, Dehdashti F, Doherty GM, Lairmore TC, Brunt LM, Moley JF. Risk of malignancy in thyroid incidentalomas identified by fluorodeoxyglucose-positron emission tomography. Surgery. 2001; 130:941–946.
7. Kang KW, Kim SK, Kang HS, Lee ES, Sim JS, Lee IG, Jeong SY, Kim SW. 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; 88:4100–4104.
8. Kim TY, Kim WB, Ryu JS, Gong G, Hong SJ, Shong YK. 18F-fluorodeoxyglucose uptake in thyroid from positron emission tomogram (PET) for evaluation in cancer patients: high prevalence of malignancy in thyroid PET incidentaloma. Laryngoscope. 2005; 115:1074–1078.
9. Are C, Hsu JF, Schoder H, Shah JP, Larson SM, Shaha AR. FDG-PET detected thyroid incidentalomas: need for further investigation? Ann Surg Oncol. 2007; 14:239–247.
10. Yang Z, Shi W, Zhu B, Hu S, Zhang Y, Wang M, Zhang J, Yao Z, Zhang Y. Prevalence and risk of cancer of thyroid incidentaloma identified by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography. J Otolaryngol Head Neck Surg. 2012; 41:327–333.
11. Bogsrud TV, Karantanis D, Nathan MA, Mullan BP, Wiseman GA, Collins DA, Kasperbauer JL, Strome SE, Reading CC, Hay ID, Lowe VJ. The value of quantifying 18F-FDG uptake in thyroid nodules found incidentally on whole-body PET-CT. Nucl Med Commun. 2007; 28:373–381.
12. Ohba K, Nishizawa S, Matsushita A, Inubushi M, Nagayama K, Iwaki H, Matsunaga H, Suzuki S, Sasaki S, Oki Y, Okada H, Nakamura H. High incidence of thyroid cancer in focal thyroid incidentaloma detected by 18F-fluorodeoxyglucose [corrected] positron emission tomography in relatively young healthy subjects: results of 3-year follow-up. Endocr J. 2010; 57:395–401.
13. Kim BH, Kim SJ, Kim H, Jeon YK, Kim SS, Kim IJ, Kim YK. Diagnostic value of metabolic tumor volume assessed by 18F-FDG PET/CT added to SUVmax for characterization of thyroid 18F-FDG incidentaloma. Nucl Med Commun. 2013; 34:868–876.
14. DeGroot LJ, Kaplan EL, McCormick M, Straus FH. Natural history, treatment, and course of papillary thyroid carcinoma. J Clin Endocrinol Metab. 1990; 71:414–424.
15. Stokkel MP, Duchateau CS, Dragoiescu C. The value of FDG-PET in the follow-up of differentiated thyroid cancer: a review of the literature. Q J Nucl Med Mol Imaging. 2006; 50:78–87.
16. Mitchell J, Parangi S. The thyroid incidentaloma: an increasingly frequent consequence of radiologic imaging. Semin Ultrasound CT MR. 2005; 26:37–46.
17. Yasuda S, Ide M. PET and cancer screening. Ann Nucl Med. 2005; 19:167–177.
18. Bertagna F, Treglia G, Piccardo A, Giubbini R. Diagnostic and clinical significance of F-18-FDG-PET/CT thyroid incidentalomas. J Clin Endocrinol Metab. 2012; 97:3866–3875.
19. Kurata S, Ishibashi M, Hiromatsu Y, Kaida H, Miyake I, Uchida M, Hayabuchi N. Diffuse and diffuse-plus-focal uptake in the thyroid gland identified by using FDG-PET: prevalence of thyroid cancer and Hashimoto's thyroiditis. Ann Nucl Med. 2007; 21:325–330.
20. Nam SY, Roh JL, Kim JS, Lee JH, Choi SH, Kim SY. Focal uptake of (18)F-fluorodeoxyglucose by thyroid in patients with nonthyroidal head and neck cancers. Clin Endocrinol (Oxf). 2007; 67:135–139.
21. Choi JY, Lee KS, Kim HJ, Shim YM, Kwon OJ, Park K, Baek CH, Chung JH, Lee KH, Kim BT. Focal thyroid lesions incidentally identified by integrated 18F-FDG PET/CT: clinical significance and improved characterization. J Nucl Med. 2006; 47:609–615.
22. Chen YK, Ding HJ, Chen KT, Chen YL, Liao AC, Shen YY, Su CT, Kao CH. 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; 25:1421–1426.
23. Yi JG, Marom EM, Munden RF, Truong MT, Macapinlac HA, Gladish GW, Sabloff BS, Podoloff DA. Focal uptake of fluorodeoxyglucose by the thyroid in patients undergoing initial disease staging with combined PET/CT for non-small cell lung cancer. Radiology. 2005; 236:271–275.
24. Chu QD, Connor MS, Lilien DL, Johnson LW, Turnage RH, Li BD. Positron emission tomography (PET) positive thyroid incidentaloma: the risk of malignancy observed in a tertiary referral center. Am Surg. 2006; 72:272–275.
25. King DL, Stack BC Jr, Spring PM, Walker R, Bodenner DL. Incidence of thyroid carcinoma in fluorodeoxyglucose positron emission tomography-positive thyroid incidentalomas. Otolaryngol Head Neck Surg. 2007; 137:400–404.
26. Ishimori T, Patel PV, Wahl RL. Detection of unexpected additional primary malignancies with PET/CT. J Nucl Med. 2005; 46:752–757.
27. Pagano L, Sama MT, Morani F, Prodam F, Rudoni M, Boldorini R, Valente G, Marzullo P, Baldelli R, Appetecchia M, Isidoro C, Aimaretti G. Thyroid incidentaloma identified by 18F-fluorodeoxyglucose positron emission tomography with CT (FDG-PET/CT): clinical and pathological relevance. Clin Endocrinol (Oxf). 2011; 75:528–534.
28. Soret M, Bacharach SL, Buvat I. Partial-volume effect in PET tumor imaging. J Nucl Med. 2007; 48:932–945.
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