The Korean Journal of Medicine

The Korean Association of Internal Medicine (대한내과학회)
권호 표지

Clinical Meaning of Diffuse $^{18}F$-FDG PET Thyroid Uptake

$^{18}F$-FDG PET상 관찰되는 미만성 갑상선섭취의 임상적 의의

  • Kim, Hee-Kyung (Department of Internal Medicine, Chonnam National University Medical School) ;
  • Yoon, Jee-Hee (Department of Internal Medicine, Chonnam National University Medical School) ;
  • Kim, Soo-Jeong (Department of Internal Medicine, Chonnam National University Medical School) ;
  • Kang, Ho-Cheol (Department of Internal Medicine, Chonnam National University Medical School)
  • 김희경 (전남대학교 의과대학 내과학교실) ;
  • 윤지희 (전남대학교 의과대학 내과학교실) ;
  • 김수정 (전남대학교 의과대학 내과학교실) ;
  • 강호철 (전남대학교 의과대학 내과학교실)
  • Published : 2011.11.01
⟨ Previous Next ⟩

Abstract

Background/Aims: Thyroid abnormalities are frequently detected in patients undergoing $^{18}F$-fludeoxyglucose positron emission tomography (FDG-PET). The clinical importance of diffuse thyroid FDG uptake (DU) has been controversial, although focal thyroid FDG uptake (FU) indicates a high probability for thyroid cancer. Methods: In total, 3,303 subjects underwent PET for cancer staging (n = 1,744) or a health screening (n = 1,559) between August 2004 and March 2006. Fifty-six (1.7%) subjects showed FU (n = 34) or DU (n = 22). Serum thyroid simulating hormone (TSH) and thyroid autoantibodies were measured with high-resolution thyroid ultrasonography (US). US-guided fine-needle aspiration cytology was performed when a nodular lesion was found. Results: Twelve of 34 (35.3%) patients with FU and 3 of 22 (13.6%) patients with DU had a malignancy. This difference in malignancy frequency was not significant between the two groups (p = 0.07). The US findings were consistent with chronic thyroiditis in 17 of 22 (77.3%) patients with DU. Three cases of DU had an apparently normal thyroid gland. In the three patients diagnosed with a malignancy in the DU group, the tumors included one papillary thyroid cancer, one primary thyroid lymphoma, and one metastatic squamous cell carcinoma from lung cancer. No correlation between TSH and $SUV_{max}$ (p = 0.086) was observed in the DU group, and the $SUV_{max}$ in patients with a malignancy was not different from that in the benign group. Conclusions: Most patients with DU had chronic autoimmune thyroiditis, but the frequency of malignancy was not different from that of the FU group. Further clinical examinations, including thyroid function tests, thyroid autoantibodies, and thyroid US are needed to diagnose chronic autoimmune thyroiditis and possible thyroid malignancy in subjects with DU.

목적: 다양한 암의 진단 및 병기 결정을 위해 $^{18}F$-FDG PET/CT (FDG PET)의 이용이 급증하면서 우연히 갑상선에 FDG 섭취 증가가 발견되는 경우가 증가하고 있다. 갑상선의 국소적 FDG 섭취 증가는 갑상선암의 위험이 높다는 사실이 알려져 있으나 미만성 FDG 섭취 증가의 임상적 의미는 불분명하다. 방법: 2004년 8월부터 2006년 3월까지 암에 대한 병기 평가(1,744예) 및 건강 검진(1,559예)을 목적으로 FDG PET을 시행한 총 3,303예 중 갑상선에 비정상적인 섭취 증가를 보인 56예(1.7%, 남 13, 여 53; 나이 $55.9\;{\pm}\;10.1$)를 대상으로 하였다. FDG 섭취 정도는 $SUV_{max}$로 평가하였다. 대상 환자에서 혈청 TSH, anti-TPO Ab와 갑상선초음파검사를 시행했으며 결절이 보이는 경우 미세침흡인세포검사를 시행하였다. 결과: FDG PET에서 갑상선 FDG 섭취 증가는 국소 섭취가 더 흔했으며(34 vs. 22) 악성의 빈도는 국소 섭취군에서 더 흔했으나 미만 섭취군과 유의한 차이는 없었다(12예[35.3%] vs. 3예[13.6%], p = 0.07). 미만 섭취군 22명 중 17예(77.3%)에서 자가면역갑상선질환이 있었고(원발성갑상선림프종 1명 포함), 3명은 정상 갑상선, 그리고 갑상선유두암과 전이성폐암이 각각 1예씩 확인되었다. 미만 섭취 군에서 TSH 증가 정도 및 anti-TPO Ab 역가와 $SUV_{max}$ 간에 상관관계는 없었으며(p = 0.086, p = 0.057) 악성소견을 보인 3예의 $SUV_{max}$는 높았으나 양성군에 비교하여 통계학적 차이는 없었다. 결론: FDG PET에서 미만성 갑상선 섭취는 대부분 자가 면역성갑상선질환을 시사했으나 암의 빈도에 있어 국소섭취와 차이가 없었고 FDG PET만으로는 암을 감별할 수 없었다. 갑상선에 미만성 FDG 섭취를 보이는 환자에서는 자가 면역갑상선질환을 진단하기 위한 혈액검사뿐만 아니라 암을 배제하기 위한 갑상선초음파검사 및 미세침흡인세포검사가 필요할 것으로 생각한다.

Keywords

References

  1. Juweid ME, Cheson BD. Positron-emission tomography and assessment of cancer therapy. N Engl J Med 2006;354:496-507. https://doi.org/10.1056/NEJMra050276
  2. 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;88:4100-4104. https://doi.org/10.1210/jc.2003-030465
  3. 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. https://doi.org/10.1097/01.MLG.0000163098.01398.79
  4. Kwak JY, Kim EK, Yun M, et al. Thyroid incidentalomas identified by 18F-FDG PET: sonographic correlation. AJR Am J Roentgenol 2008;191:598-603. https://doi.org/10.2214/AJR.07.3443
  5. Liu Y. Clinical significance of thyroid uptake on F18-fluorodeoxyglucose positron emission tomography. Ann Nucl Med 2009; 23:17-23. https://doi.org/10.1007/s12149-008-0198-0
  6. 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. https://doi.org/10.1016/j.otohns.2007.02.037
  7. Hosaka Y, Tawata M, Kurihara A, Ohtaka M, Endo T, Onaya T. The regulation of two distinct glucose transporter (GLUT1 and GLUT4) gene expressions in cultured rat thyroid cells by thyrotropin. Endocrinology 1992;131:159-165. https://doi.org/10.1210/en.131.1.159
  8. Gordon BA, Flanagan FL, Dehdashti F. Whole-body positron emission tomography: normal variations, pitfalls, and technical considerations. AJR Am J Roentgenol 1997;169:1675-1680. https://doi.org/10.2214/ajr.169.6.9393189
  9. Shreve PD, Anzai Y, Wahl RL. Pitfalls in oncologic diagnosis with FDG PET imaging: physiologic and benign variants. Radiographics 1999;19:61-77.
  10. Yasuda S, Shohtsu A, Ide M, et al. Chronic thyroiditis: diffuse uptake of FDG at PET. Radiology 1998;207:775-778.
  11. Karantanis D, Bogsrud TV, Wiseman GA, et al. Clinical significance of diffusely Increased 18F-FDG uptake in the thyroid gland. J Nucl Med 2007;48:896-901. https://doi.org/10.2967/jnumed.106.039024
  12. Tateishi U, Gamez C, Dawood S, et al. Chronic thyroiditis in patients with advanced breast carcinoma: metabolic and morphologic changes on PET-CT. Eur J Nucl Med Mol Imaging 2009;36:894-902. https://doi.org/10.1007/s00259-008-1048-y
  13. Kurata S, Ishibashi M, Hiromatsu Y, et al. Diffuse and diffuseplus- 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. https://doi.org/10.1007/s12149-007-0030-2
  14. Mitchell JC, Grant F, Evenson AR, Parker JA, Hasselgren PO, Parangi S. Preoperative evaluation of thyroid nodules with 18FDG-PET/CT. Surgery 2005;138:1166-1174. https://doi.org/10.1016/j.surg.2005.08.031
  15. Bae JS, Chae BJ, Park WC, et al. Incidental thyroid lesions detected by FDG-PET/CT: prevalence and risk of thyroid cancer. World J Surg Oncol 2009;7:63. https://doi.org/10.1186/1477-7819-7-63
  16. Leboulleux S, Schroeder PR, Schlumberger M, Ladenson PW. The role of PET in follow-up of patients treated for differentiated epithelial thyroid cancers. Nat Clin Pract Endocrinol Metab 2007;3:112-121. https://doi.org/10.1038/ncpendmet0402
  17. Lazar V, Bidart JM, Caillou B, et al. Expression of the Na+/Isymporter gene in human thyroid tumors: a comparison study with other thyroid-specific genes. J Clin Endocrinol Metab 1999;84:3228-3234. https://doi.org/10.1210/jc.84.9.3228
  18. Filetti S, Damante G, Foti D. Thyrotropin stimulates glucose transport in cultured rat thyroid cells. Endocrinology 1987;120: 2576-2581. https://doi.org/10.1210/endo-120-6-2576
  19. Lewis PJ, Salama A. Uptake of fluorine-18-fluorodeoxyglucose in sarcoidosis. J Nucl Med 1994;35:1647-1649.
  20. Keyes JW Jr, Harkness BA, Greven KM, Williams DW 3rd, Watson NE Jr, McGuirt WF. Salivary gland tumors: pretherapy evaluation with PET. Radiology 1994;192:99-102.
  21. Braams JW, Pruim J, Freling NJ, et al. Detection of lymph node metastases of squamous-cell cancer of the head and neck with FDG-PET and MRI. J Nucl Med 1995;36:211-216.
  22. Choi JW, Lee JH, Baek JH, et al. Diagnostic accuracy of ultrasound and 18-F-FDG PET or PET/CT for patients with suspected recurrent papillary thyroid carcinoma. Ultrasound Med Biol 2010;36:1608-1615. https://doi.org/10.1016/j.ultrasmedbio.2010.07.013
  23. Cohen MS, Arslan N, Dehdashti F, et al. Risk of malignancy in thyroid incidentalomas identified by fluorodeoxyglucose-positron emission tomography. Surgery 2001;130:941-946. https://doi.org/10.1067/msy.2001.118265
  24. Are C, Hsu JF, Ghossein RA, Schoder H, Shah JP, Shaha AR. Histological aggressiveness of fluorodeoxyglucose positronemission tomogram (FDG-PET)-detected incidental thyroid carcinomas. Ann Surg Oncol 2007;14:3210-3215. https://doi.org/10.1245/s10434-007-9531-4
  25. Cooper DS, Doherty GM, Haugen BR, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2009;19:1167-1214. https://doi.org/10.1089/thy.2009.0110
  26. Dean DS, Gharib H. Epidemiology of thyroid nodules. Best Pract Res Clin Endocrinol Metab 2008;22:901-911. https://doi.org/10.1016/j.beem.2008.09.019