Diagnostic value of CT density in patients with diffusely increased FDG uptake in the thyroid gland on PET/CT images

You Mie Han, Young Chul Kim, Eun Kyung Park, Jae Gol Choe

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


OBJECTIVE. The purpose of this article is to determine the diagnostic significance of thyroid density as determined by CT in patients with a diffuse hypermetabolic thyroid on PET/CT images. SUBJECTS AND METHODS. One hundred twelve patients were enrolled in this study, and all underwent PET/CT and a thyroid function test between August 2007 and December 2008. The 56 study patients enrolled had visible 18F-FDG uptake in the thyroid, whereas the 56 control subjects had no visible FDG uptake. Maximum standardized uptake values (SUV max), Hounsfield units, thyroid-stimulating hormone levels, free thyroxine levels, and visual assessments of thyroid CT densities (grades 0-2) were evaluated. Analyses were performed to identify variables that differed between patients and control subjects and to examine relationships between Hounsfield unit and SUVmax values, free thyroxine level, or thyroid-stimulating hormone level. RESULTS. Mean Hounsfield unit and SUV max values were significantly different between the two groups (p < 0.001), and SUVmax values were found to be significantly different between grades. Free thyroxine and thyroid-stimulating hormone levels were also significantly different between thyroid density grades 0 and 2 (p < 0.001). A strongly negative relationship was found between Hounsfield units and SUVmax values (r = 0.75), whereas Hounsfield units were found to be weakly correlated with free thyroxine level (r = 0.36) and thyroid-stimulating hormone level (r = -0.33). CONCLUSION. CT density is closely related to FDG uptake, and low CT density coupled with high FDG uptake suggests a change in thyroid tissue composition and is probably helpful for assessing the disease process and thyroid function of patients whose thyroid show diffuse FDG uptake on FDG PET/CT.

Original languageEnglish
Pages (from-to)223-228
Number of pages6
JournalAmerican Journal of Roentgenology
Issue number1
Publication statusPublished - 2010 Jul


  • CT
  • FDG
  • PET
  • Thyroid gland

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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