Comparative diagnostic accuracy and tumor uptake of 68Ga-FAPI PET/CT versus 18F-FDG PET/CT for detecting primary tumors, lymph node, and distant metastases in biliary tract cancers: A systematic review and meta-analysis.

Abstract

e16235 Background: Biliary tract cancers (BTCs) are aggressive malignancies with poor prognosis, necessitating accurate diagnostic tools for confirming detection and staging. This study compared the diagnostic accuracy of 68Ga-FAPI PET/CT and 18F-FDG PET/CT, in detecting BTCs, including primary tumors, nodal involvement, and distant metastases. The study also evaluated tumor-to-background ratio (TBR) and standardized uptake values (SUV) to assess the effectiveness of these modalities in tumor visualization and quantification. Methods: We systematically searched five databases (PubMed, EMBASE, Web of Science, Scopus, and Cochrane Library) for studies published up to March 2024. Eligible studies included BTC patients who underwent both 68Ga-FAPI PET/CT and 18F-FDG PET/CT within a short time frame. Statistical analysis employed a random-effects model with subgroup analysis for intrahepatic cholangiocarcinoma (IHCC). Heterogeneity was evaluated using the Cochrane Q test and I² statistic. We used R software (v.4.4.2) for statistical analysis. Results: Out of 9,748 records identified, seven studies (five prospective, two retrospective) met the inclusion criteria. All were conducted between 2021 and 2024, included patients aged 38–80 years. The pooled sensitivity and specificity of 68Ga-FAPI PET/CT and 18F-FDG PET/CT scans in detecting BTC were 81% (95% CI: 47-95%, I2= 76%) and 87% (95% CI: 59-97%, I2= 0%), and 95% (95% CI: 85-98%, I2= 0%) and 87% (95% CI: 15-99%, I2= 0%) , respectively. The pooled odds of detecting BTC for 68Ga-FAPI PET/CT versus 18F-FDG PET/CT was 4.87 (95% CI: 1.75–13.56, I2 = 0.0%, p = 0.60), indicating a statistically significant preference for 68Ga-FAPI. In the IHCC subgroup, the pooled odds was 2.98 (95% CI: 0.86–10.38, I2 = 0.0%, p = 0.63) favors 68Ga-FAPI. Furthermore, 68Ga-FAPI demonstrated significantly higher tumor uptake compared to 18F-FDG PET/CT, with pooled mean differences in SUVmax of 6.47 (95% CI: 1.81–11.13) and TBRmax of 9.45 (95% CI: 3.88–15.03) across BTCs. Subgroup analysis for IHCC showed a trend favoring 68Ga-FAPI, though the TBRmax difference did not reach statistical significance (mean difference: 7.71, 95% CI: -0.58–16.01). For lymph node metastasis detection, 68Ga-FAPI outperformed 18F-FDG with an odds ratio of 2.81 (95% CI: 1.07–7.35), and for distant metastases, the odds ratio was 3.45 (95% CI: 1.12–10.63). Conclusions: 68Ga-FAPI PET/CT outperformed 18F-FDG PET/CT in diagnosing BTCs, including IHCC, with higher tumor uptake and improved diagnostic accuracy particularly in detecting metastatic BTCs. . These findings highlight the potential of 68Ga-FAPI PET/CT as a superior imaging modality for BTCs, though further studies are needed to confirm its clinical utility and address heterogeneity in results.