Objectives: To systematically determine the diagnostic accuracy of 18-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([18F]FDG-PET/MRI) for the detection of liver metastases and evaluate the sources of heterogeneity in the reported results.
Methods: PubMed and EMBASE databases were searched up until December 31, 2017, to identify original research studies reporting the diagnostic performance (Se and Sp) of PET/MRI for liver metastases, in comparison with PET/CT. Study quality was assessed using QUADAS-2. The summary Se and Sp of the studies were estimated using hierarchical modeling methods. To determine causes of study heterogeneity, the presence of a threshold effect was analyzed, and meta-regression analysis was performed.
Results: Of 546 articles screened, eight suitable articles were identified, with seven for per-lesion analysis, and four for per-patient analysis. The meta-analytic summary Se and Sp for per-patient-based analysis were 99.2% (95% CI, 31.4-100.0%, I2 = 89.4%) and 98.6% (95% CI, 84.0-99.9%, I2 = 0.0%), respectively, while for per-lesion-based analysis they were 95.4% (95% CI, 78.3-99.2%, I2 = 99.7%) and 99.3% (95% CI, 93.8-99.9%, I2 = 96.5%). PET/MRI showed higher Se (95.4% vs. 68.3%) and Sp (99.3% vs. 95.8%) than PET/CT. Meta-regression analysis showed five significant factors affecting study heterogeneity: study subject characteristics, study design, MRI technique (DWI, HBP after injection of liver-specific contrast media), imaging review method, and reference standard.
Conclusion: The diagnostic accuracy of [18F]FDG-PET/MRI for liver metastasis was high overall, but substantial heterogeneity was found. Further randomized controlled studies or prospective studies are needed to investigate the role of PET/MRI in liver metastasis in comparison with PET/CT.
Key points: • [ 18 F]FDG-PET/MRI has high meta-analytic Se and Sp for the diagnosis of liver metastasis. • PET/MRI using DWI and HBP images significantly increased diagnostic accuracy. • Study heterogeneity was associated with subject characteristics, study design, MRI technique, image review method, and reference standard.
Keywords: Fluorodeoxyglucose F18; Liver; Magnetic resonance imaging; Neoplasms; Positron emission tomography-computed tomography.