Preclinical detection of liver fibrosis using dual-modality photoacoustic/ultrasound system.

Liver fibrosis is a major cause for increasing mortality worldwide. Preclinical research using animal models is required for the discovery of new anti-fibrotic therapies, but currently relies on endpoint liver histology. In this study, we investigated a cost-effective and portable photoacoustic/ultrasound (PA/US) imaging system as a potential non-invasive alternative. Fibrosis was induced in mice using CCl4 followed by liver imaging and histological analysis. Imaging showed significantly increased PA features with higher frequency signals in fibrotic livers versus healthy livers. This corresponds to more heterogeneous liver structure resulting from collagen deposition and angiogenesis. Importantly, PA response and its frequency were highly correlated with histological parameters. These results demonstrate the preclinical feasibility of the PA imaging approach and applicability of dual PA/US system.