Change in pericardial fat volume in postmenopausal women with papillary thyroid cancer undergoing TSH suppressive therapy

Abstract Purpose: We aimed to examine the changes in body composition under TSH suppression in postmenopausal women with DTC. Methods: The body composition was assessed by the volumes as following; fat tissues of the epicardium and abdominal visceral and subcutaneous areas; bilateral psoas muscle or thigh muscle. Volumetric measurements were performed using computed tomography (CT) scans using fluorine-18 fluorodeoxyglucose positron emission tomography/CT (¹⁸F-FDG PET/CT). Forty-three postmenopausal women with DTC underwent ¹⁸F-FDG PET/CT for tumor monitoring. Results: The patients’ median age was 50.0 years, and median body mass index (BMI) was 23.53 (interquartile range[IQR]: 22.19- 24.92) at the initial ¹⁸F-FDG PET/CT. The median follow-up period was 19.24 months (IQR: 17.24–21.79). No significant changes in weight or BMI were observed during follow-up. Volumes of fat and muscles did not changed significantly except epicardial fat volume. The epicardial fat volume significantly increased during the follow-up period. The epicardial fat volumes were correlated with visceral fat volume, respectively, however, the changing ratio was only correlated with TSH suppression on multiple regression analysis. Conclusion: Both skeletal muscle and abdominal fat volumes did not change, whereas epicardial fat volume increased over less than 2 years of observation under TSH suppressive therapy. Further research is needed for the harmonization of benefits or losses with the optimal TSH concentration in postmenopausal women.