Whole-Body ¹⁸F-FDG PET and ¹⁸F-FDG PET/CT in Patients with Suspected Paraneoplastic Syndrome: A Systematic Review and Meta-Analysis of Diagnostic Accuracy

The purpose of this study was to assess the diagnostic performance of whole-body ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT for detection of underlying malignancy in patients with clinically suspected neurologic and nonneurologic paraneoplastic syndromes. Methods: A systematic search was performed in PubMed (Medline), Embase, and Scopus (last updated November 2016) to identify relevant published studies reporting the performance of ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT in patients with suspected paraneoplastic syndrome. Histopathologic confirmation or clinical follow-up was considered as the reference standard. Pooled estimates, with 95% confidence intervals (CIs), of sensitivity, specificity, and diagnostic odds ratio were calculated. A summary receiver-operating-characteristic curve was constructed, and the area under the curve (AUC) was determined along with the Q* index. Results: Twenty-one studies including a total of 1,293 individual patients suspected of having a paraneoplastic syndrome and who underwent ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT examinations met our inclusion criteria. There was moderate to high heterogeneity among the included studies. The pooled sensitivity, specificity, and diagnostic odds ratio of ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT for the detection of underlying malignancy were 0.81 (95% CI, 0.76-0.86), 0.88 (95% CI, 0.86-0.90), and 34.03 (95% CI, 18.76-61.72), respectively. The AUC and the Q* index were 0.916 (SE, 0.018) and 0.849, indicating excellent diagnostic accuracy. The diagnostic accuracy was slightly improved after studies with high applicability concerns were excluded (AUC, 0.931; SE, 0.020). In a subgroup analysis, ¹⁸F-FDG PET/CT was found to have a significantly higher specificity (0.89 vs. 0.79) than ¹⁸F-FDG PET alone, with no evidence of significant difference in the overall performance (AUC, 0.930 vs. 0.891; 2-tailed P value for difference, 0.31). Conclusion: This meta-analysis of available studies demonstrates that whole-body ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT has high diagnostic accuracy and moderate to high sensitivity and specificity for detection of underlying malignancy in patients suspected of having a paraneoplastic syndrome.