Japanese Journal of Radiology

, Volume 36, Issue 3, pp 181–193 | Cite as

Clinical significance of patterns of increased [18F]-FDG uptake in the thyroid gland: a pictorial review

  • Fumihiro Tsubaki
  • Seiji Kurata
  • Junichi Tani
  • Akiko Sumi
  • Kiminori Fujimoto
  • Toshi Abe


In the diagnosis and staging of oncologic patients, [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is well recognized as an important functional imaging modality. FDG-PET also has been used for cancer screening in healthy individuals. In general, the normal thyroid gland shows absent or low uptake on FDG-PET, which is often identified as an incidental finding on PET. Today, thyroid FDG uptake can be seen in three patterns: diffuse; focal; and diffuse-plus-focal. Diffuse thyroid uptake is mainly considered an indicator of chronic thyroiditis. Focal thyroid uptake has been associated with malignancy (range 25–50%). Diffuse-plus-focal uptake is not well recognized and might also indicate a risk of malignancy. Understanding the patterns of thyroid FDG uptake is thus important for nuclear medicine physicians or radiologists when giving recommendations to the referring physician. In this pictorial review, we show the clinical significance of different patterns of thyroid uptake on FDG-PET [PET/computed tomography (CT)], including ultrasonography (US) findings.


FDG-PET Focal uptake Diffuse uptake Thyroid cancer 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Japan Radiological Society 2017

Authors and Affiliations

  • Fumihiro Tsubaki
    • 1
  • Seiji Kurata
    • 1
  • Junichi Tani
    • 2
  • Akiko Sumi
    • 1
  • Kiminori Fujimoto
    • 1
  • Toshi Abe
    • 1
  1. 1.Department of RadiologyKurume University School of MedicineKurumeJapan
  2. 2.Division of Endocrinology and Metabolism, Department of MedicineKurume University School of MedicineKurumeJapan

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