Abstract
Objective: To evaluate the technique of native collagen fluorescence imaging for assessing the extent of welded areas for tissues exposed to different near-infrared (NIR) laser wavelengths. Background: Native fluorescence imaging may be used to identify the distribution of collagen and elastin in tissues. Our past work demonstrated that different welding strengths were obtained under the same laser power conditions using different NIR wavelengths. The role of collagen in tissue welding experiments is not well understood. Methods: Two new NIR tunable lasers were used to weld canine skin. The welded areas on the surface and in cross sections were analyzed by measuring the spatial distribution of native collagen fluorescence at 380 nm excited by 340 nm radiation. Results: The results show that native collagen fluorescence imaging is a useful technique for analyzing the extent of tissue welds produced under a range of laser exposures. Fluorescence imaging reveals the depth of laser interaction with the tissue as well as evaluating collateral damage to the tissue surface. The welded volume obtained in skin using Cunyite laser exposure at 1,430 nm is deeper than that produced with Forsterite laser exposure at 1,250 nm. The post welded tensile strength for the same power density is greater for the Cunyite lasers. Ablated tissue on the surface is more prevalent with Forsterite laser welding at 1,250 nm than with Cunyite at 1,430 nm. Conclusion: Native collagen fluorescence can distinguish between tissue welds that have been produced by different NIR wavelengths. Tissue welding using l,430nm radiation is more effective than that using l,250nm.
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