Diffusely Increased 18F-FDG Uptake in the Thyroid Gland and Risk of Thyroid Dysfunction: A Cohort Study.

Young Kim,Yoosoo Chang,Yejin Kim,Hyemi Kwon,Soo Kim,Seungho Ryu,Jiin Ahn,Eun-Jung Rhee

doi:10.3390/jcm8040443

Young Kim, Yoosoo Chang + Show 6 more

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https://doi.org/10.3390/jcm8040443

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Abstract

The impact of incidentally identified diffuse thyroid FDG uptake on 18F-FDG PET/CT scan on the incidence of thyroid dysfunction remains unclear. We examined the association of diffuse thyroid FDG uptake with the development of thyroid dysfunction. This cohort study involved 39,098 Korean adults who were free of malignancy and thyroid disease at baseline and underwent regular health checkup examinations including an 18F-FDG whole body PET/CT scan, thyroid-stimulating hormone and free thyroxine. The participants were annually or biennially followed for up to 5 years. A parametric proportional hazard model was used to estimate the adjusted hazard ratio (HR) and 95% confidence interval (CI). Diffuse thyroid uptake was positively associated with increased risk of thyroid dysfunction in both the cross-sectional and cohort studies. During 104,261.4 person-years of follow-up, 102 incident hypothyroidism cases and 172 hyperthyroidism cases were identified. Multivariable-adjusted HR (95% CI) for incident hypothyroidism or hyperthyroidism comparing diffuse thyroid uptake to no uptake were 15.72 (9.23–26.77) and 7.38 (4.23–12.87), respectively. In this large cohort, incidentally, identified diffuse thyroid uptake on 18F-FDG PET/CT was associated with increased risk of both prevalent and incident thyroid dysfunction. Therefore, baseline and follow-up evaluations in individuals with diffuse thyroid uptake may help identify individuals with thyroid dysfunction.

Highlights

2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron-emission tomography/ computed tomography (PET-CT) is widely used for staging, restaging, recurrence detection, and monitoring of treatment response in numerous malignant diseases [1]
Baseline diffuse thyroid FDG uptake was significantly associated with increased prevalence of hypothyroidism or hyperthyroidism
The associations between diffuse thyroid FDG uptake and incidence of thyroid dysfunction were similar across subgroups with no significant interactions by age (

Summary

Introduction

2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron-emission tomography/ computed tomography (PET-CT) is widely used for staging, restaging, recurrence detection, and monitoring of treatment response in numerous malignant diseases [1]. Combining metabolic and anatomical information, 18F-FDG PET/CT detects malignant lesions by identifying regions with increased glycolytic metabolism and expression of membrane glucose transporter (GLUT) proteins [1,2]. Increased FDG uptake is found in malignant lesions, and in infectious or inflammatory lesions. Focal uptake by the thyroid is associated with a 25–50% risk of malignancy [5]. Diffuse FDG uptake by the thyroid gland has been reported in about 0.6–3.3% of the population and is associated with increased prevalence of hypothyroidism, hyperthyroidism, or thyroiditis in cross-sectional studies [4,6,7,8]. Follow-up studies of patients having diffuse thyroid FDG uptake without clinically significant thyroid abnormalities are not available

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