FAP and Myocardial fibrosis: Radiotracers targeting fibroblast activation protein (FAP),such as 68Gallium fibroblast activation protein inhibitor (68Ga-FAPI),have shown promising application in the early detection and quantitativeassessment of myocardial fibrosis, providing new molecular imaging tools for thestudy of the pathological mechanism and individualized treatment of HFpEF.