Diagnostic performance of dual-time 18F-FDG PET in the diagnosis of pulmonary nodules: a meta-analysis

Rationale and objective: Perform a comprehensive meta-analysis evaluating the diagnostic performance of dual time point deoxy-2-[(18)F]fluoro-D-glucose positron emission tomography (FDG-PET) in the diagnosis of pulmonary nodules.

Materials and methods: MEDLINE, EMBASE, and PUBMED were queried between January 2000 and January 2011. Studies were included if they: 1) used dual time point FDG-PET as a diagnostic test for pulmonary nodules, 2) used pathology or clinical follow-up as the reference standard, and 3) reported absolute number of true-positive (TP), true-negative (TN), false-positive (FP), and false-negative (FN) results or stated sufficient data to derive these values. Summary sensitivity (SN), summary specificity (SP), positive and negative likelihood ratios (LR+) and (LR-), and diagnostic odds ratio were calculated. Heterogeneity of the results was assessed using Forest plots and the value of inconsistency index (I(2)).

Results: Inclusion criteria were fulfilled by 10 articles with a total of 816 patients and 890 pulmonary nodules. The summary sensitivity was 85% (82%-89% at 95% confidence interval [CI]) and summary specificity was 77% (CI: 72%-81%), with a LR+ of 2.7 (CI: 1.4-5.2) and a LR- of 0.26 (CI: 0.14-0.49). Diagnostic odds ratio was 11 (CI: 3.8-32.2). Significant heterogeneity was found in the sensitivity (I(2) = 77%) and specificity (90.3%).

Conclusion: Dual time point FDG-PET demonstrates similar sensitivity and specificity to single time point FDG-PET in the diagnosis of pulmonary nodules. The additive value of the dual time point FDG-PET is questionable, primarily because of the significant overlap of benign and malignant nodule FDG-PET characteristics and lack of consensus criteria for quantitative thresholds to define nodules as malignant.