The role of [18F]-2-fluoro-2-deoxy-d-glucose-positron emission tomography in thyroid nodules with indeterminate fine-needle aspiration biopsy: systematic review and meta-analysis of the literature

D. Vriens, J. de Wilt, G. van der Wilt, R. Netea-Maier, W. Oyen and L. de Geus-Oei

Department of Nuclear Medicine, Radboud University Nijmegen Medical Center, the Netherlands.
Oct, 2011



Indeterminate results at fine-needle aspiration biopsy (FNAB) of thyroid nodules pose a clinical dilemma, because only 20\% to 30\% of patients suffer from malignancy. Previous studies suggested that the false-negative ratio of [(18)F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) is very low; therefore, it may help identify patients who would benefit from (hemi)thyroidectomy. A systematic literature search was performed in 5 databases. After assessment, the identified studies were analyzed for heterogeneity, and the extracted data of test characteristics were pooled using a random-effects model. Threshold effects were examined, and publication bias was assessed. The query resulted in 239 records, of which 6 studies met predefined inclusion criteria. Data from 225 of the 241 described patients could be extracted. There was mild to moderate heterogeneity in study results (inconsistency index [I(2)] = 0.390-0.867). The pooled prevalence of malignancy was 26\%. Pooled sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95\% (95\% confidence interval [95\% CI], 86\%-99\%), 48\% (95\% CI, 40\%-56\%), 39\% (95\% CI, 31\%-47\%), 96\% (95\% CI, 90\%-99\%), and 60\% (95\% CI, 53\%-67\%), respectively. Sensitivity increased to 100\% for the 164 lesions that measured >15 mm in greatest dimension. There was no evidence of threshold effects or publication bias. A negative FDG-PET scan in patients who had thyroid nodules >15 mm with indeterminate FNAB results excluded thyroid cancer in a pooled population of 225 patients. Conversely, a positive FDG-PET result did not identify cancer, because approximately 50\% of these patients had benign nodules. The authors concluded that the incorporation of FDG-PET into the initial workup of such patients before surgery deserves further investigation.