Reviewed by Danielle Ellis, B.Sc.Oct 1 2024
In a recent study published in the Journal of Biomedical Optics, researchers studied the shape and function of lymphatic vessels in vivo using SWIR fluorescence imaging. They compared two imaging modalities (SWIR, 900–1800 nm, and near-infrared first window, NIR-I, 700–900 nm) with two fluorescent probes (indocyanine green, ICG, and silver sulfide quantum dots, QDs) to find out how well SWIR imaging provided detailed lymphatic images in an animal model.
A multispectral imaging system helps visualize and measure circulation within lymphatic vessels. Image Credit: C. Hansen et al.
The lymphatic system, which is the body's second-biggest circulatory network, is essential for the immune system and fluid balance maintenance. Notwithstanding its significance, investigating lymphatic channel function has proven difficult because of the lack of suitable imaging methods.
One of the primary obstacles to research on the lymphatic system is the great variety in the form and arrangement of its vessels. Lymphatic vessels are more difficult to find and study than blood vessels since they do not always have predictable locations and branching patterns. Their small size also makes them more challenging.
Early imaging techniques, such as X-rays, fluorescence lymphangiography, lymphoscintigraphy, and photoacoustic imaging, can show the structure and activity of lymphatic vessels, but they have difficulty accurately measuring lymph movement over time.
In comparison to conventional near-infrared (NIR) imaging, recent developments in shortwave-infrared (SWIR) imaging offer a possible answer by delivering sharper and more detailed images of lymphatic circulation.
The outcomes showed that autofluorescence background and scattering are greatly reduced by SWIR imaging, producing sharper images.
In particular, SWIR imaging with QDs substantially quadrupled the resolution and sensitivity, improving the capacity to differentiate lymphatic vessels, whereas SWIR imaging with ICG provided 1.7 times higher resolution and sensitivity than NIR-I. Comparing this enhancement to traditional NIR-I imaging enables more precise in vivo vessel size estimates.
The study found that SWIR imaging outperforms conventional NIR-I imaging methods in terms of picture resolution, especially when using silver sulfide QDs. This innovation in imaging technology holds enormous potential for increasing understanding of the lymphatic system and its activities.
Journal Reference:
Hansen, C., et al. (2024) Dynamic multispectral NIR/SWIR for in vivo lymphovascular architectural and functional quantification. Journal of Biomedical Optics. doi.org/10.1117/1.jbo.29.10.106001.