Non-linear imaging and characterization of atherosclerotic arterial tissue using combined SHG and FLIM microscopy

Area of Science:

• Biomedical Optics
• Materials Science
• Pathology

Background:

• Atherosclerosis is a major cause of mortality globally.
• Accurate characterization of atherosclerotic tissue is crucial for diagnosis.
• Current diagnostic methods may benefit from advanced imaging techniques.

Purpose of the Study:

• To employ combined SHG-FLIM microscopy for characterizing arterial tissue affected by atherosclerosis.
• To differentiate between normal arterial wall and atherosclerotic plaque using optical properties.
• To assess the potential of SHG-FLIM for clinical diagnostic applications.

Main Methods:

• Utilized combined second-harmonic generation (SHG) and fluorescence lifetime imaging microscopy (FLIM).
• Analyzed optical properties including mean fluorescence lifetime, aspect ratio, and correlation length.
• Compared measurements from normal arterial wall samples with those from atherosclerotic plaque depositions.

Main Results:

• Mean fluorescence lifetime was shorter in plaque depositions (1260 ± 80 ps) than in normal arterial wall (1480 ± 100 ps), distinguishing collagen from lipids.
• Normal arterial wall showed higher anisotropy (Aspect Ratio 0.37 ± 0.02) compared to plaque (0.61 ± 0.02).
• Correlation length differentiated collagen fiber bundles (2.0 ± 0.6 µm) from cholesterol depositions (4.1 ± 0.6 µm).

Conclusions:

• Combined SHG-FLIM microscopy effectively characterizes atherosclerotic arterial tissue.
• The method allows discrimination between collagen and lipids based on fluorescence lifetime.
• Optical parameters like anisotropy and correlation length aid in differentiating tissue components.
• This technique shows promise for future clinical and in vivo applications in atherosclerosis diagnosis.