Clinical research on physiological thymic uptake of 131 I in post-operative patients with differentiated thyroid cancer

Abstract

Objective To explore the clinical features and 131I whole body scans (WBS) characteristics of physiological thymic uptake of 131I in post-operative patients with differentiated thyroid cancer (DTC).Methods One thousand eight hundred and eighty-two WBS were performed on the 3-5 day after 1nI therapy in post-operative patients with DTC between 2007 and 2013.On the basis of thyroglobulin and thyroglobulin antibody measurement,other imaging and clinical follow-up,the mediastinal activity was attributed to physiological thymic uptake of 131I.For such patients,their data were reviewed retrospectively.Results Physiological thymic uptake of 131I were confirmed in 16 patients.All of them were under the age of 45.Fifteen patients received at least two therapeutic doses of 131I,and there was only one patient to be found physiological thymic uptake of 131I on the first treatment.The pattem of physiological thymic uptake of 131I was classified as diffuse or dumbbell.Thymic uptake of 131I became more prominent with repeated treatments.Conclusions For the next appropriate treatment,it is essential to acknowledge that physiological thymic uptake of 131I in patients with DTC under the age of 45 is an important cause of false-positive WBS. Key words: Thyroid neoplasms; Thymus gland; Iodine radioisotopes; Brachytherapy