Feasibility of [68Ga]Ga-FAPI PET Molecular Imaging in Atherosclerosis Compared with [18F]FDG in Oncological Patients

<b>Background:</b> Cardiovascular disease (CVD), driven primarily by atherosclerosis, is a major cause of morbidity and mortality among cancer patients. This study aims to evaluate the diagnostic value of [⁶⁸Ga]Ga-FAPI-PET as a novel molecular imaging tool for atherosclerosis, compared with established, non-specific [¹⁸F]FDG. <b>Methods:</b> We retrospectively analyzed twenty patients with bladder cancer who underwent [⁶⁸Ga]Ga-FAPI positron-emission tomography/magnetic resonance (PET/MR) and [¹⁸F]FDG positron emission tomography/computed tomography (PET/CT) at staging. The target-to-background ratio (TBRs) of both tracers were assessed along six arterial segments, and uptake patterns were compared between the two radiotracers. Additionally, associations between the intensity of PET-active lesions and certain CVD risk factors, as well as the intake of acetylsalicylic acid (ASA), were evaluated. <b>Results:</b> [⁶⁸Ga]Ga-FAPI detects significantly more active arterial PET lesions and shows significantly higher uptake than [¹⁸F]FDG in the per-lesion analysis (TBR_FAPI: 1.7 ± 0.5 vs. TBR_FDG: 1.4 ± 0.2; difference 19%; <i>p</i> < 0.001) and in the patient-based analysis (TBR_FAPI: 1.7 ± 0.4 vs. TBR_FDG: 1.4 ± 0.2; difference 19%; <i>p</i> = 0.018). Arterial hypertension (<i>p</i> < 0.001), dyslipidemia (<i>p</i> < 0.001), and particularly type 2 diabetes mellitus (<i>p</i> < 0.001; difference 34%), were significantly associated with elevated [⁶⁸Ga]Ga-FAPI expression compared to [¹⁸F]FDG uptake. ASA therapy was associated with a significant reduction in arterial [⁶⁸Ga]Ga-FAPI expression than [¹⁸F]FDG (<i>p</i> = 0.02). <b>Conclusions:</b> [⁶⁸Ga]Ga-FAPI-PET imaging, demonstrating superior detection of atherosclerotic activity compared to [¹⁸F]FDG, might be a promising molecular imaging marker for atherosclerosis.