Value of 18F-FDG-PET/PET-CT in differentiated thyroid carcinoma with radioiodine-negative whole-body scan: a meta-analysis.

AIM The aim of this study was to evaluate the diagnostic accuracy of 18F-fluorodeoxyglucose-PET (FDG-PET) and FDG-PET/computed tomography (CT) in the detection of recurrent or metastatic differentiated thyroid carcinoma (DTC) that was not identified by radioiodine whole-body scintigraphy (WBS). PATIENTS AND METHODS A total of 25 studies (comprising 789 patients) that were published from January 1990 to September 2008 were reviewed. These studies evaluated the role of FDG-PET and FDG-PET/CT in the detection of recurrent or metastatic DTC that radioiodine WBS failed to detect. Systematic methods were used to identify, select, and evaluate the methodological quality of the studies and to summarize the overall findings of sensitivity and specificity. RESULTS In total, 17 studies with 571 patients who had recurrent or metastatic DTC and a radioiodine-negative whole-body scan were collected, and the overall patient-based sensitivity and specificity of FDG-PET were 0.835 [95% confidence interval (CI): 0.791-0.873] and 0.843 (95% CI: 0.791-0.886), respectively. Of these studies, six included lesion-based data, totaling 237 lesions, and the pooled lesion-based sensitivity and specificity were 0.916 (95% CI: 0.863-0.953) and 0.775 (95% CI: 0.660-0.865), respectively. The pooled sensitivity and specificity in the DTC patients who presented with elevated serum thyroglobulin and negative 131I scan were 0.885 (95% CI: 0.828-0.929) and 0.847 (95% CI: 0.715-0.934), respectively. In the six studies where the 165 patients were diagnosed by using FDG-PET/CT, pooled sensitivity and specificity were 0.935 (95% CI: 0.870-0.973) and 0.839 (95% CI: 0.723-0.920), respectively. CONCLUSION FDG-PET is especially effective in detecting patients with elevated thyroglobulin levels and normal radioiodine WBS; FDG-PET/CT is a more sensitive method in the follow-up of thyroid cancer recurrence or metastases, particularly in those with negative WBS.