18F-FAPI Outperforms 18F-FDG PET/CT in Detecting Focal Inflammation as a Cause of Refractory In-Stent Restenosis

Inflammation-associated coronary artery disease (I-CAD) is a recognized yet underdiagnosed cause of refractory in-stent restenosis. Conventional imaging modalities often lack sensitivity for detecting focal inflammatory activity. A 74-year-old woman with recurrent ISR was admitted to our institution. Dual-tracer ¹⁸F-FAPI and ¹⁸F-FDG PET/CT revealed locally increased radiotracer uptake within the left anterior descending artery (LAD) stent segment, with more intense uptake on 18F-FAPI than on 18F-FDG. We present the dual-tracer PET/CT findings in this patient with recurrent in-stent restenosis, suggesting active peri-stent fibroblast-related remodeling and an inflammation-associated mechanism. The patient was subsequently managed with anti-inflammatory therapy rather than repeated revascularization.