Comparison of whole-body 18F-FDG SPECT and posttherapeutic 131I scintigraphy in the detection of metastatic thyroid cancer

Purpose: The usefulness of fluorine 18 fluorodeoxyglucose (F-18-FDG) imaging in differentiated thyroid cancer (DTC) has been demonstrated by investigators. The aim of this study is to compare the ability of fluorodeoxyglucose (FDG)-single photon emission computed tomography (SPECT) to detect metastatic DTC with posttherapeutic iodine131 (I-131) scintigraphy. Methods: 239 patients (78 men, 161 women; age range, 23-76 years, mean 45 years); All patients underwent FDG-SPECT and I-131 whole-body scan. Results: The sensitivity of F-18-FDG and I-131 imaging in the patients with high hTg levels is 48.7% (114/234) and 50.4% (118/234) respectively. However, the combined sensitivity of both protocols is 89.7% (210/234). In the patients with I-131 Imaging negative, the sensitivity of F-18-FDG is 79.3%,but in the patients with I-131 imaging positive, the sensitivity of F-18-FDG is only 18.6%. Conclusion: This study with I-131 and F-18-FDG in FDG-SPECT further demonstrates the single study of I-131 whole body scan or F-18-FDG imaging can not provide a high enough sensitivity for the detection of metastatic thyroid cancer. But, the combined protocols can get better results for the staging of thyroid carcinoma with the alternating uptake of I-131 and F-18-FDG. (C) 2008 Elsevier Inc. All rights reserved.