Comparing the clinical value of baseline [⁶⁸ Ga]Ga-FAPI-04 PET/CT and [¹⁸F]F-FDG PET/CT in pancreatic ductal adenocarcinoma: additional prognostic value of the distal pancreatitis.

Abstract

Anatomical and molecular staging strategies are needed for the personalized treatment of localized pancreatic ductal adenocarcinoma (PDAC). This study evaluated the performance of [⁶⁸ Ga]Ga-FAPI-04 and [¹⁸F]F-FDG PET/CT on the disease staging and prognostic value of patients with localized PDAC on contrast-enhanced (CE)-CT images. Patients with suspected localized PDAC on CE-CT were recruited for static [⁶⁸ Ga]Ga-FAPI-04 and ¹⁸[F]F-FDG and PET/CT, and select patients underwent simultaneous 60-min dynamic ⁶⁸ Ga-FAPI-04 PET/CT. The diagnostic and staging performances of the static PET/CT results were evaluated by delineating regions of interest in the primary tumor, whole pancreas, and distal pancreas in both types of scans and then evaluating correlations between the PET/CT findings and clinicopathological characteristics. Furthermore, Kaplan-Meier and hazard ratio (log-rank) methods were used to evaluate the prognostic value of the combined dynamic [⁶⁸ Ga]Ga-FAPI-04 and static [¹⁸F]F-FDG PET/CT method. We included 49 patients with histologically confirmed PDAC adenocarcinomas; 32 underwent 60-min dynamic [⁶⁸ Ga]Ga-FAPI-04 PET/CT imaging simultaneously. The static [⁶⁸ Ga]Ga-FAPI-04 method had significantly higher accuracy and uptake values than the static [¹⁸F]F-FDG method for primary PDAC lesions, metastatic lymph nodes, and distal metastases. Furthermore, 18.4% and 10.2% of the patients' stages changed after using the [⁶⁸ Ga]Ga-FAPI-04 and [¹⁸F]F-FDG PET/CT methodologies, respectively, compared to the CE-CT-designated stage. The Ki values obtained from dynamic [⁶⁸ Ga]Ga-FAPI-04 PET/CT did not differ between PDAC and distal obstructive pancreatitis lesions. Pathologically enlarged tumor size, poor differentiation, and perineural invasion were associated with increased [⁶⁸ Ga]Ga-FAPI-04 uptake but not with [¹⁸F]F-FDG uptake. The preoperative prognostic performance of [⁶⁸ Ga]Ga-FAPI-04 was better than that of [¹⁸F]F-FDG. Interestingly, combined [⁶⁸ Ga]Ga-FAPI-04 and [¹⁸F]F-FDG uptake results in the whole pancreas could further stratify patients based on their postoperative prognosis. ⁶[⁶⁸ Ga]Ga-FAPI-04 PET/CT was more sensitive and accurate than [¹⁸F]F-FDG PET/CT for tumor, node, and metastasis staging of PDAC identified on CE-CT. Additionally, [⁶⁸ Ga]Ga-FAPI-04 uptake was significantly associated with pathologically aggressive tumor features. Combined [⁶⁸ Ga]Ga-FAPI-04 and [¹⁸F]F-FDG PET/CT findings improved the prognostic value, potentially providing a non-invasive guide for clinical management. Finally, increased fibroblast activity in PDAC-induced obstructive pancreatitis may be associated with poor patient survival rates.