Highlighting Fibroblasts Activation in Fibrosis: The State-of-The-Art Fibroblast Activation Protein Inhibitor PET Imaging in Cardiovascular Diseases

Abstract

Fibrosis is a common healing process that occurs during stress and injury in cardiovascular diseases. The evolution of fibrosis is associated with cardiovascular disease states and causes adverse effects. Fibroblast activation is responsible for the formation and progression of fibrosis. The incipient detection of activated fibroblasts is important for patient management and prognosis. Fibroblast activation protein (FAP), a membrane-bound serine protease, is almost specifically expressed in activated fibroblasts. The development of targeted FAP-inhibitor (FAPI) positron emission tomography (PET) imaging enabled the visualisation of FAP, that is, incipient fibrosis. Recently, research on FAPI PET imaging in cardiovascular diseases increased and is highly sought. Hence, we comprehensively reviewed the application of FAPI PET imaging in cardiovascular diseases based on the state-of-the-art published research. These studies provided some insights into the value of FAPI PET imaging in the early detection of cardiovascular fibrosis, risk stratification, response evaluation, and prediction of the evolution of left ventricular function. Future studies should be conducted with larger populations and multicentre patterns, especially for response evaluation and outcome prediction.

PET/CT in leukemia: utility and future directions

“…The patient underwent a [ 68 Ga]Ga-FAPI PET scan, revealing significant cardiac uptake initially, which subsequently resolved following treatment [130]. This finding highlights the potential value of [ 68 Ga]Ga-FAPI PET imaging in evaluating treatment response in such cases [130].…”

“…Moreover, [ 68 Ga]Ga-FAPI exhibited a superior tumor to background ratio in surrounding tissue, making it a valuable tool for visualizing myeloid sarcoma [129]. Cui et al conducted a review in which they observed a patient diagnosed with eosinophilic leukemia who presented with eosinophilic myocarditis, a prevalent complication affecting approximately half of eosinophilic leukemia patients [130]. The patient underwent a [ 68 Ga]Ga-FAPI PET scan, revealing significant cardiac uptake initially, which subsequently resolved following treatment [130].…”

“…Cui et al conducted a review in which they observed a patient diagnosed with eosinophilic leukemia who presented with eosinophilic myocarditis, a prevalent complication affecting approximately half of eosinophilic leukemia patients [130]. The patient underwent a [ 68 Ga]Ga-FAPI PET scan, revealing significant cardiac uptake initially, which subsequently resolved following treatment [130]. This finding highlights the potential value of [ 68 Ga]Ga-FAPI PET imaging in evaluating treatment response in such cases [130].…”

Molecular subtypes of ischemic heart disease based on circadian rhythm

“…Cardiac fibroblasts play a central role in maintaining homeostasis of the extracellular matrix (ECM). Fibroblast activation protein is expressed by myofibroblasts derived from smooth muscle cells in human atherosclerotic plaques and is involved in the pathogenesis and progression of atherosclerosis, particularly in inflammatory processes 51 , 52 . This promotes the deterioration and progression of CAD, which also matches that Type2 is predominantly in the advanced stage and development of CAD.…”