Is fluorine-18 fluorodeoxyglucose positron emission tomography useful for the thyroid nodules with indeterminate fine needle aspiration biopsy? a meta-analysis of the literature

Background: The indeterminate fine needle aspiration biopsy (FNAB) results present a clinical dilemma for physicians. The aim of this study was to evaluate the diagnostic accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography (F-18-FDG PET) in the detection of these indeterminate lesions. Methods: Seven studies (involving a total of 267 patients) published before November 2012 were reviewed. Systematic methods were used to identify, select, and evaluate the methodological quality of the studies as well as to summarize the overall findings of sensitivity and specificity. Results: A total number of 70 patients were confirmed to have malignant lesions, with a cancer prevalence of 26.2% (70/267; ranging from 19.6% to 40.0% in these studies). The pooled sensitivity and specificity of PET or PET/CT for the detection of cancer was 89.0% (95% CI: 79.0% similar to 95.0%) and 55.0% (95% CI: 48.0% similar to 62.0%), respectively. There was no evidence of threshold effects or publication bias. The area [+/- standard error (+/- SE)] under the symmetrical sROC curve was 0.7207 +/- 0.1041. Although SUVmax was higher in malignant lesions (P < 0.01), there was still a great overlap. The best cut-off value of SUVmax for differentiation was 2.05; but with a high sensitivity of 89.8% and low specificity of 42.0%. Conclusion: F-FDG PET or PET/CT showed a high sensitivity in detecting thyroid cancers in patients with indeterminate FNAB results. Further examination was strongly recommended when an FDG-avid lesion was detected.