Journal Article Do TSH, FT3 and FT4 impact BAT visualization of clinical FDG-PET/CT images?

Nishii, Ryuichi  ,  Nagamachi, Shigeki  ,  Mizutani, Yuichi  ,  Terada, Tamasa  ,  Kiyohara, Syogo  ,  Wakamatsu, Hideyuki  ,  Fujita, Seigo  ,  Higashi, Tatsuya  ,  Yoshinaga, Keiichiro  ,  Saga, Tsuneo

2018 ( 8 )  , pp.1 - 9 , 2018-02 , Hindawi (John Wiley & Sons, Inc.)
[Objectives] Several researchers have reported that type 2 idothyronine deiodinase (D2) is considered to be important for the synergism of thyroid hormone (TH) and to be required to generate the T3 from T4 in the BAT, which maintains the normal acute thermogenic function of BAT. However, to date, details about the relationship between visualization of BAT on FDG-PET/CT and the effect of TH remain unknown. In this study, we retrospectively analyze BAT visualization on FDG-PET/CT in patients with various conditions and TH levels. [Methods] In this retrospective investigation, we reviewed images from all patients who underwent clinical FDG-PET/CT studies from October 2010 to July 2015, and categorized patients in 5 groups: (i) Thyroid hormone withdrawal (THW) group; (ii) Recombinant human thyrotropin (rhTSH) group; (iii) Hypothyroidism group; (iv) hyperthyroidism group; and (v) BAT group. Total of sixty-two FDG-PET/CT imaging studies in fifty-nine patients were performed. A total of sixty-two FDG-PET/CT imaging studies in fifty-nine patients were performed. To compare each group; gender; age; body weight; serum TSH, FT3, FT4 levels; and outside temperature were evaluated. [Results] No significant visualization of BAT was noted in any of the images in the THW, rhTSH, hypothyroidism, and hyperthyroidism groups. Serum TSH level was significantly high in the rhTSH group and significantly low in the hyperthyroidism group. Elevated serum TSH was noted in the THW and hypothyroidism group. All patients in the BAT group were in a euthyroid state. When the BAT-negative and -positive patient groups were compared, it was noted that the minimum and maximum temperature on the day of the PET study and maximum temperature of the one day before of the PET study were significantly lower in BAT positive group than in all others those of other groups. [Conclusions] Elevated TSH condition before RIT, hyperthyroidism orhypothyroidism did not significantly impact BAT visualization of clinical FDG-PET/CT images.

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