Diagnostic performance of FAPI PET-CT vs 18F FDG PET-CT in evaluation of Liver tumors: A Systematic Review and Meta-Analysis.

INTRODUCTION: Primary liver tumors constitutes one of the most common tumors. These are aggressive tumors with poor survival. Fluorodeoxy Glucose PET/CT, most commonly used functional imaging shows limited tracer retention and poor tumor to background ratios. Novel 68Ga-fibroblast-activation-protein inhibitor (FAPI) PET/CT has shown better tracer uptake and detection efficacy in liver tumors. However, most of the available literature is from single center studies with limited no of patients. So, we tried to review and analyse the head to head comparison of 18F FDG PET/CT and FAPI PET-CT in evaluation of Liver tumors.
METHODS: Literature available on head to head comparison of diagnostic accuracy of 18F FDG PET-CT and 68Ga FAPI PET-CT was searched in databases like PubMed, SCOPUS, EMBASE and Google Scholar for published original studies till April 2023. The relevant studies were selected and assessed using the Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS – 2) checklist. A random-effect model was used for calculating pooled sensitivity and specificity. They were represented with 95% confidence intervals (95% CI) and demonstrated in Forest plots. I-square statistic was used to assess heterogeneity in the studies.
RESULTS: Pooled sensitivity and specificity of FAPI PET-CT and 18F-FDG PET-CT for detection of primary liver tumors was 94.3% (95%CI: 90.6%-96.8%); 89.3% (95%CI: 71.8%-97.7%) and 56.1 (95%CI: 49.7%-62.5%); 96.4% (95%CI: 81.7-99.9%) respectively. Pooled sensitivity for detection of extrahepatic metastatic disease was 92.2% (range: 88.1-100%; 95%CI: 87.8%-95.4%) and 72.4 % (range: 69.8-76.5; 95%CI: 65.9%-78.2%) respectively. Also, the SUVmax and TBR was higher for FAPI PET-CT than 18F-FDG PET-CT in all the included studies.
DISCUSSION AND CONCLUSION: Overall, FAPI PET-CT showed higher sensitivity for detection of liver tumors with better SUV max as well as TBR than 18F-FDG PET-CT.