Correlation between anti-thyroid peroxidase antibody levels and diffuse thyroid uptake of 18F-fluorodeoxyglucose in Hashimoto\u2019s thyroiditis: a retrospective study

Naoki Edo,Koji Morita,Tatsuro Kaminaga,Hiromi Edo,Masumi Ogawa,Kazuhisa Tsukamoto,Toshio Ishikawa,Miki Sakamoto,Erina Okamura,Hiroko Okinaga

doi:10.1186/s13044-018-0058-5

Naoki Edo, Koji Morita + Show 8 more

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https://doi.org/10.1186/s13044-018-0058-5

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Abstract

BackgroundOn 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), diffuse uptake in the thyroid gland is often observed in patients with Hashimoto’s thyroiditis. In this study, we evaluated the factors associated with diffuse uptake by comparing Hashimoto’s thyroiditis patients with or without diffuse uptake in the thyroid.MethodsA retrospective study was conducted of 18 patients with Hashimoto’s thyroiditis who underwent blood tests, thyroid ultrasonography, and FDG-PET during the period from 2014 to 2015. The patients were divided into two groups: one with diffuse thyroid uptake (group 1, n = 13) and one without diffuse thyroid uptake (group 2, n = 5). Clinical and laboratory parameters, including maximum standardized uptake in the thyroid (SUVmax), which was defined as the higher value obtained in either the right or left thyroid lobe, were compared in the two groups.ResultsThe frequency of abnormal findings, such as a rough or heterogeneous pattern, was significantly higher in group 1 (p < 0.01), as were anti-thyroid peroxidase (TPO) antibody titers, anti-thyroglobulin (Tg) antibody titers, and SUVmax (p < 0.01). The frequency of hypothyroidism did not differ significantly in the two groups. Anti-TPO and anti-Tg titers were positively correlated with SUVmax (r = 0.856, p < 0.01 and r = 0.821, p < 0.01, respectively); in univariate analysis, anti-TPO titer was predictive of SUVmax (p < 0.01).ConclusionsThe results of the current study suggest that Hashimoto’s thyroiditis patients with high titers of anti-thyroid antibodies are likely to exhibit intense diffuse FDG uptake in the thyroid, and that thyroid function may be clearly impaired, even in the presence of mild FDG uptake in the thyroid.

Highlights

On 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), diffuse uptake in the thyroid gland is often observed in patients with Hashimoto’s thyroiditis
Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) is a functional imaging technique known as FDG-PET that exploits the typically increased rate of glycolysis in specific cell types, such as malignant tumors and inflammatory tissue [1, 2]
Serum free T4 was significantly higher in patients with diffuse thyroid uptake, but it was similar in groups 1 and 2 after excluding those undergoing replacement therapy consisting of levothyroxine

Summary

Introduction

On 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), diffuse uptake in the thyroid gland is often observed in patients with Hashimoto’s thyroiditis. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) is a functional imaging technique known as FDG-PET that exploits the typically increased rate of glycolysis in specific cell types, such as malignant tumors and inflammatory tissue [1, 2]. With regard to the thyroid, a normal thyroid gland is not visible or shows only low-grade FDG uptake on FDG-PET [3, 4]. The increasing use of FDGPET has led to incidental identification of patients with increased FDG uptake in the thyroid gland. FDG uptake in the thyroid predominantly conforms to one of two patterns: focal and diffuse. The prevalences of incidental focal and diffuse uptake in the thyroid reportedly vary from 0.1 to 4.8% and 0.1 to 4.5%, respectively [5].

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