Nonalcoholic fatty liver disease (
NAFLD), emerging as one of the most common chronic
liver diseases including simple steatosis and non-
alcoholic steatohepatitis (NASH), is likely to progress to
liver fibrosis and hepatic
carcinoma if not treated in time. Therefore, early diagnosis and treatment of
NAFLD are necessary. Currently, liver biopsy, as the gold standard for clinical diagnosis of
NAFLD, is not widely accepted by patients due to its invasiveness. However, other non-invasive methods that had been reported for
NAFLD (such as magnetic resonance imaging, positron emission tomography, and ultrasound) still suffer from low resolution and sensitivity, which are available as a guide for liver biopsy sometimes. As a non-invasive modality with high spatiotemporal resolution and superior sensitivity, optical imaging methods have been widely favored in recent years, mainly including fluorescence imaging, photoacoustic imaging, and bioluminescence imaging. With these optical imaging approaches, a series of optical probes based on optical and molecular-specific design have been developed for the
biomarker diagnosis and research of diseases. In this review, we summarize the existing non-invasive optical imaging probes for the detection of
biomarkers in
NAFLD, including microenvironment (viscosity, polarity), ROS, RSS,
ions,
proteins, and
nucleic acids. Design strategies for optical imaging probes and their applications in
NAFLD bioimaging are discussed and focused on. We also highlight the potential challenges and prospects of designing new generations of optical imaging probes in
NAFLD studies, which will further enhance the diversity, practicality, and clinical feasibility of
NAFLD research.