18F-FAPI PET/CT for Early Detection and Severity Assessment of Intestinal Fibrosis in a Mouse Model

Area of Science:

• Molecular imaging
• Oncology
• Gastroenterology

Background:

• Intestinal fibrosis is a significant complication of inflammatory bowel diseases, such as Crohn's disease.
• Early detection and accurate staging of intestinal fibrosis are crucial for effective management and treatment.
• Current diagnostic methods have limitations in detecting early-stage fibrosis and assessing its severity.

Purpose of the Study:

• To evaluate the feasibility of using 18F-fibroblast activation protein (FAP) inhibitor positron emission tomography/computed tomography (18F-FAPI PET/CT) for detecting early-stage intestinal fibrosis.
• To assess the capability of 18F-FAPI PET/CT in determining the severity of intestinal fibrosis in a mouse model.
• To explore the correlation between 18F-FAPI uptake and FAP expression or fibrosis scores at different disease stages.

Main Methods:

• A dextran sulfate sodium (DSS)-induced mouse model of intestinal fibrosis was established.
• Mice underwent 18F-FAPI PET/CT scanning at multiple time points (3, 6, 9, and 12 weeks) post-DSS exposure.
• Correlation analyses were performed between 18F-FAPI uptake, FAP expression, and histopathological fibrosis scores.

Main Results:

• 18F-FAPI uptake showed a strong positive correlation with FAP expression throughout all stages of fibrosis (r=0.90).
• In early-stage fibrosis, 18F-FAPI PET/CT demonstrated high diagnostic efficacy (AUC=0.95) and strong correlation with fibrosis score (r=0.89).
• Diagnostic performance and correlation decreased significantly in later stages of fibrosis (AUC=0.46, r=-0.20).

Conclusions:

• 18F-FAPI PET/CT is a promising tool for the early identification of intestinal fibrosis.
• The technique effectively distinguishes the degree of fibrosis in early stages, correlating well with established scoring systems.
• Findings suggest 18F-FAPI PET/CT can provide valuable insights for treatment decisions in patients with Crohn's disease and intestinal fibrosis.