Objective : The aim of this study was to explore the clinical characteristics of renal metastatic cancer, the methods for its detection by radioiodine (131I), and the response to 131I treatment in fourteen patients with renal metastases from differentiated thyroid carcinoma (DTC).Subjects and methods : DTC patients (n = 2,955) that received treatment with 131I were retrospectively analyzed. Scans (131I-WBS, 31I-SPECT/CT and/or 18F-FDG-PET/CT) were performed after an oral therapeutic dose of 131I. Therapeutic efficacy was evaluated based on changes in Tg and anatomical imaging changes at renal lesions.Results : Among these 14 patients, 11 had avidity for 131I, but three patients did not accumulate 131I after 131I treatment. In the 11 131I-positive renal lesions, 10 cases were detected by 131I-SPECT/CT combined with another imaging modality and one case by 131I-WBS combined with ultrasonography (US). In the three 131I-negative renal lesions, two cases were detected by 18F-FDG-PET/CT and one case by computed tomography (CT). In 11 patients with 131I-avid renal metastases, Serum Tg levels in 81.82% (9/11) patients showed a gradual decline, and 18.18% (2/11) of the patients showed a significant elevation. There was no marked difference in serum Tg before the last 131I treatment (Z = 0.157; p = 0.875). Only one patient presented partial response, eight patients exhibited stable disease, and renal metastases progressed in two patients showing progressive disease. No patients reached complete response.Conclusion : 131I-SPECT/CT, combined with another imaging modality after 131I-WBS, can contribute to the early detection of renal metastases of DTC. 131I therapy is a feasible and effective treatment for most DTC renal metastases with avidity for 131I. Arq Bras Endocrinol Metab. 2014;58(3):260-9
Thyroglobulin doubling time offers a better threshold than thyroglobulin level for selecting optimal candidates to undergo localizing [18F]FDG PET/CT in non-iodine avid differentiated thyroid carcinoma