Molecular Imaging Probes for Early Detection and Staging of Liver Fibrosis.

Liver fibrosis, a progressive condition marked by excessive extracellular matrix deposition and activation of hepatic stellate cells, often develops asymptomatically in its early stages, leading to delayed clinical intervention. Conventional imaging techniques typically fail to detect mild fibrosis, resulting in diagnosis only at advanced stages such as cirrhosis, when therapeutic efficacy is significantly compromised. Recent advances in molecular imaging have facilitated the development of targeted contrast agents that enhance diagnostic sensitivity by selectively binding to fibrosis-specific biomarkers or responding to pathological microenvironmental changes. These include both nonresponsive probes that accumulate in fibrotic tissue and activatable probes sensitive to enzymes, small molecules, and other fibrosis-associated signals. This review systematically summarizes these emerging strategies and evaluates their potential for improving early diagnosis, staging accuracy, and therapeutic monitoring, thereby guiding future development and applications in hepatic fibrosis management.