Head-to-Head Comparison of 68Ga-FAPI PET/CT and FDG PET/CT for the Detection of Peritoneal Metastases: Systematic Review and Meta-Analysis

AJR Am J Roentgenol. 2022 Nov 2. doi: 10.2214/AJR.22.28402. Online ahead of print.

Abstract

Background: FDG PET/CT has limited diagnostic performance for peritoneal metastasis. The 68Ga-fibroblast activation protein inhibitor (68Ga-FAPI) targets tumor stroma, leading to high accumulation across cancer types. Objective: To conduct a meta-analysis to compare the diagnostic performance of 68Ga-FAPI PET/CT and FDG PET/CT in detecting PM based on studies providing head-to-head comparisons between the two tests. Evidence Acquisition: PubMed, Embase, and Cochrane Library databases were searched through July 2022 to identify studies reporting head-to-head comparison of 68Ga-FAPI PET/CT and FDG PET/CT for detection of PM. Reference standard was classified as histopathology in all patients, or as combination of histopathology, clinical, imaging, laboratory, and follow-up information (i.e., multidisciplinary reference standard). Random-effects statistical model was applied to conduct a meta-analysis of tests' diagnostic performances in patient-based and lesion-based analyses. QUADAS-2 and QUADAS-C tools were used to assess study quality. Evidence Synthesis: Eleven studies were included; patient-based analysis comprised nine studies with 340 patients, and lesion-based analysis comprised four studies with 222 lesions. Pooled sensitivity of 68Ga-FAPI PET/CT was significantly higher than that of FDG PET/CT in patient-based analysis [98.2% (95% CI: 96.1-100.0%) vs 55.9% (95% CI: 33.9-77.9%)] and lesion-based analysis [99.9% (95% CI: 99.5-100.0%) vs 27.3% (95% CI: 11.2-43.4%)]. Eight studies were rated as high risk of bias in the reference standard domain because the multidisciplinary reference standard was not sufficiently explained and may have included one of the two index tests, which would have artificially increased sensitivity. Specificity was reported in three studies as 100.0% for both tests; these studies were considered at uncertain risk of bias in the patient selection domain because patients with benign peritoneal conditions may have been excluded, resulting in underestimation of potential false-positive results. Conclusion: Current evidence suggests excellent sensitivity of 68Ga-FAPI PET/CT for the detection of PM, in comparison to poorer sensitivity of FDG PET/CT. However, most included studies had high risk of bias, with need for further studies that could more convincingly characterize true- and false-positive results. Clinical Impact: The use of 68Ga-FAPI PET/CT may offer substantially improved sensitivity compared with FDG PET/CT for the evaluation of PM, facilitating surgical candidate selection and planning.

Publication types

  • Review