Comparative analysis of two timepoints on [¹⁸F]FAPI-42 PET/CT in various cancers.

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Oncology Imaging

Background:

• Fibroblast activation protein (FAP) is a transmembrane protease implicated in tumor stroma.
• [18F]FAPI tracers offer promising diagnostic potential in oncology.
• Optimizing imaging protocols enhances diagnostic accuracy.

Purpose of the Study:

• To evaluate the biodistribution, detection rate, and lesion uptake of [18F]FAPI-42 at early and late time points.
• To compare the performance of early [18F]FAPI-42 PET/CT with 2-[18F]FDG PET/CT.
• To determine the feasibility of early acquisition for [18F]FAPI-42 PET/CT protocols.

Main Methods:

• Prospective study of 60 patients undergoing [18F]FAPI-42 PET/CT at early and late intervals.
• Visual and semiquantitative analysis of tracer uptake in lesions and normal organs.
• Subgroup analysis comparing early [18F]FAPI-42 PET/CT with 2-[18F]FDG PET/CT in 11 patients.

Main Results:

• Early [18F]FAPI-42 PET/CT demonstrated higher lesion detection rates and visual scores compared to late imaging.
• Lesion uptake was significantly higher in early images, with decreased uptake in late images (p < 0.05).
• Early [18F]FAPI-42 PET/CT showed superior detection and uptake compared to 2-[18F]FDG PET/CT.

Conclusions:

• Early [18F]FAPI-42 PET/CT provides consistent lesion detection and uptake.
• Early imaging reduces tracer retention in the biliary system compared to late imaging.
• Acquisition at an early time point is a feasible strategy for optimizing [18F]FAPI-42 PET/CT protocols.