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

Abstract

Purpose: This study is to investigate the [⁶⁸Ga]Ga-DOTA-FAPI PET/CT diagnosis performance in biliary tract carcinoma (BTC) and analyze the association between [⁶⁸Ga]Ga-DOTA-FAPI PET/CT and clinical indexes.

Methods: A prospective study (NCT05264688) was performed between January 2022 and July 2022. Fifty participants were scanned using [⁶⁸Ga]Ga-DOTA-FAPI and [¹⁸F]FDG PET/CT and acquired pathological tissue. We employed the Wilcoxon signed-rank test to compare the uptake of [⁶⁸Ga]Ga-DOTA-FAPI and [¹⁸F]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 [⁶⁸Ga]Ga-DOTA-FAPI detection rate was greater than [¹⁸F]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 [⁶⁸Ga]Ga-DOTA-FAPI was higher than [¹⁸F]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 [⁶⁸Ga]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 [⁶⁸Ga]Ga-DOTA-FAPI metabolic tumor volume and carbohydrate antigen199 (CA199) (Pearson r = 0.436, p = 0.002) was confirmed.

Conclusion: [⁶⁸Ga]Ga-DOTA-FAPI had a higher uptake and sensitivity than [¹⁸F]FDG in the diagnosis of BTC primary and metastatic lesions. The correlation between [⁶⁸Ga]Ga-DOTA-FAPI PET/CT indexes and FAP expression, CEA, PLT, and CA199 were confirmed.

Trial registration: clinicaltrials.gov: NCT 05,264,688.

Keywords: Biliary tract carcinoma; FAPI; Fibroblast activation protein; PET/CT.