Photoacoustic imaging of vascular hyperpermeability

Area of Science:

• Biomedical Imaging
• Vascular Biology
• Diagnostic Technology

Background:

• Vascular hyperpermeability (VHP) is a hallmark of various diseases, including cancer, infection, and inflammation.
• Current methods for VHP assessment are often invasive or lack real-time capabilities.
• Developing non-ionizing imaging techniques for VHP is crucial for accurate disease monitoring.

Purpose of the Study:

• To develop and validate a real-time, non-ionizing photoacoustic imaging (PAI) method for quantitative analysis of vascular hyperpermeability (VHP).
• To investigate the utility of Evans blue (EB) as a contrast agent for PAI of VHP.
• To assess the efficacy of antivascular ultrasound (AVUS) in inducing and imaging VHP.

Main Methods:

• Hepatocellular carcinoma (HCC) mouse models were used, with one leg serving as the control.
• VHP was induced using ultrasound, with and without microbubbles (AVUS).
• Photoacoustic imaging (PAI) was performed before and after VHP induction, with signal unmixing for Evans blue (EB).

Main Results:

• Antivascular ultrasound (AVUS) significantly increased the photoacoustic (PA) signal of EB (0.18 ± 0.02 au to 0.60 ± 0.19 au), indicating marked VHP.
• Ultrasound alone showed a minor increase in PA signal (0.14 ± 0.04 to 0.18 ± 0.05).
• Histology confirmed vascular disruption and EB extravasation in AVUS-treated tumors, correlating with elevated EB concentrations.

Conclusions:

• Photoacoustic imaging (PAI) provides a promising non-invasive platform for the quantitative assessment of vascular hyperpermeability (VHP).
• The combination of Evans blue (EB) and PAI allows for robust detection of VHP.
• Future temporal analysis of EB signal changes could enhance quantitative permeability assessment in diverse disease contexts.