Fibrotic Disease: from Signaling Pathways and Biomarkers to Molecular Imaging.

Fibrotic diseases are characterized by excessive accumulation of extracellular matrix (ECM) components following tissue injury, ultimately leading to organ dysfunction and failure. The progression of fibrosis is governed by complex molecular signaling pathways, including TGF-β, PDGF, FGF, CTGF, VEGF, and many others, which regulate myofibroblast activation, ECM production, and tissue remodeling. Traditional diagnostic modalities such as magnetic resonance imaging (MRI), computed tomography (CT), and biopsy are limited in their ability to distinguish active fibrogenesis from established fibrosis or detect early molecular changes. Recent advances in molecular imaging such as the development of targeted radiotracers and MRI contrast agents-have enabled more precise detection and characterization of fibrotic processes at both preclinical and clinical levels. The integration of molecular imaging with targeted probes holds promise for improving early diagnosis, guiding therapeutic strategies, and advancing clinical management of fibrosis. This review presents a comprehensive overview of the molecular mechanisms underlying fibrogenesis, highlights key signaling pathways and biomarkers, and discusses current and emerging molecular imaging agents for fibrotic diseases diagnosis and monitoring.