Diagnostic accuracy of 18F-FDG and 68 Ga-FAPi PET/CT for patients with gastric carcinoma: a systematic review and meta-analysis.

Objective: This systematic review aims to assess the diagnostic performance of FDG PET/CT and FAPi PET/CT in patients with gastric carcinoma, specifically for the evaluation of primary tumors, metastatic lymph nodes, and metastatic lesions.

Methods: Following PRISMA guidelines, relevant databases were searched until January 20, 2023. Studies reporting histopathology or surgical outcomes as the reference standard were included. Pooled estimates of diagnostic accuracy were generated using meta-analysis.

Results: Six studies with 167 patients who underwent FDG PET/CT and 169 patients who underwent FAPi PET/CT were included. For the detection of primary gastric carcinoma, FDG PET/CT demonstrated a pooled sensitivity of 0.86 (95% CI 0.47-0.98) and specificity of 0.70 (95% CI 0.39-0.90). The pooled positive likelihood ratio was 2.9 (95% CI 1.0-8.4), and the negative likelihood ratio was 0.21 (95% CI 0.03-1.30). The diagnostic odds ratio was 14 (95% CI 1-224), and the area under the SROC curve was 0.82. For FAPi PET/CT, pooled sensitivity and specificity for detecting primary gastric carcinoma were 0.90 (95% CI 0.90-0.90) and 0.50 (95% CI 0.50-0.50), respectively. The pooled positive and negative likelihood ratios were 1.8 (95% CI 1.8-1.8) and 0.20 (95% CI 0.20-0.20), respectively. The diagnostic odds ratio was 9 (95% CI 9-9), and the area under the SROC curve was 0.54.

Conclusion: FAPi PET/CT demonstrated comparable diagnostic performance to FDG PET/CT in the diagnosis of primary gastric carcinoma, lymph nodal metastases, and metastatic lesions. When compared to histopathology or surgical findings, FAPi PET/CT showed good sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio.