Dynamic multispectral NIR/SWIR for in vivo lymphovascular architectural and functional quantification.

Area of Science:

• Biomedical Imaging
• Lymphatic System Research
• Optical Imaging Techniques

Background:

• The lymphatic system's crucial role in fluid balance and immunity is hindered by limited functional characterization methods.
• Current imaging techniques struggle with resolution and contrast for detailed lymphatic vessel analysis.

Purpose of the Study:

• To investigate the utility of shortwave-infrared (SWIR) fluorescence imaging for *in vivo* lymphatic structure and function assessment.
• To compare SWIR imaging with conventional near-infrared first window (NIR-I) imaging for lymphatic visualization.

Main Methods:

• Evaluated subsurface lymphatic circulation in Sprague-Dawley rats using NIR-I (700-900 nm) and SWIR (900-1800 nm) fluorescence imaging.
• Compared indocyanine green (ICG) and silver sulfide quantum dots (QDs) as contrast agents for SWIR lymphatic imaging after intradermal footpad injection.

Main Results:

• SWIR imaging demonstrated reduced scattering and autofluorescence compared to NIR-I.
• SWIR imaging with ICG showed 1.7x better resolution and sensitivity than NIR-I.
• SWIR imaging with QDs achieved nearly 2x better resolution and sensitivity, with enhanced vessel distinguishability.

Conclusions:

• SWIR imaging provides superior resolution and sensitivity for lymphatic vessel visualization compared to NIR-I.
• Silver sulfide QDs in SWIR imaging offer enhanced lymphatic imaging capabilities over ICG in NIR-I.