Clinical prospective study of Gallium 68 (68Ga)-labeled fibroblast-activation protein inhibitor PET/CT in the diagnosis of biliary tract carcinoma

PurposeThis study is to investigate the [Ga-68]Ga-DOTA-FAPI PET/CT diagnosis performance in biliary tract carcinoma (BTC) and analyze the association between [Ga-68]Ga-DOTA-FAPI PET/CT and clinical indexes. Methods A prospective study (NCT 05264688) was performed between January 2022 and July 2022. Fifty participants were scanned using [Ga-68]Ga-DOTA-FAPI and [F-18]FDG PET/CT and acquired pathological tissue. We employed the Wilcoxon signed-rank test to compare the uptake of [Ga-68]Ga-DOTA-FAPI and [F-18]FDG, and the McNemar test was used to compare the diagnostic efficacy between the two tracers. Spearman or Pearson correlation was used to assess the association between [(68) Ga]Ga-DOTA-FAPI PET/CT and clinical indexes. Results In total, 47 participants (mean age 59.09 +/- 10.98 [range 33-80 years]) were evaluated. The [Ga-68]Ga-DOTA-FAPI detection rate was greater than [F-18]FDG in primary tumors (97.62% vs. 85.71%), nodal metastases (90.05% vs. 87.06%), and distant metastases (100% vs. 83.67%). The uptake of [Ga-68]Ga-DOTA-FAPI was higher than [F-18]FDG in primary lesions (intrahepatic cholangiocarcinoma, 18.95 +/- 7.47 vs. 11.86 +/- 0.70, p = 0.001; extrahepatic cholangiocarcinoma, 14.57 +/- 6.16 vs. 8.80 +/- 4.74, p = 0.004), abdomen and pelvic cavity nodal metastases (6.91 +/- 6.56 vs. 3.94 +/- 2.83, p < 0.001), and distant metastases (pleural, peritoneum, omentum, and mesentery, 6.37 +/- 4.21 vs. 4.50 +/- 1.96, p = 0.01; bone, 12.15 +/- 6.43 vs. 7.51 +/- 4.54, p = 0.008). There was a significant correlation between [Ga-68]Ga-DOTA-FAPI uptake and fibroblast-activation protein (FAP) expression (Spearman r = 0.432, p = 0.009), carcinoembryonic antigen (CEA) (Pearson r = 0.364, p = 0.012), and platelet (PLT) (Pearson r = 0.35, p = 0.016). Meanwhile, a significant relationship between [Ga-68]Ga-DOTA-FAPI metabolic tumor volume and carbohydrate antigen199 (CA199) (Pearson r = 0.436, p = 0.002) was confirmed. Conclusion [Ga-68]Ga-DOTA-FAPI had a higher uptake and sensitivity than [F-18]FDG in the diagnosis of BTC primary and metastatic lesions. The correlation between [Ga-68]Ga-DOTA-FAPI PET/CT indexes and FAP expression, CEA, PLT, and CA199 were confirmed.