Multiscale anisotropy analysis of second-harmonic generation collagen imaging of mouse skin

Significance: Morphological collagen signatures are important for tissue function, particularly in the tumor microenvironment. A single algorithmic framework with quantitative, multiscale morphological collagen feature extraction may further the use of collagen signatures in understanding fundamental tumor progression. Aim: A modification of the 2D wavelet transform modulus maxima (WTMM) anisotropy method was applied to both digitally simulated collagen fibers and second-harmonic-generation imaged collagen fibers of mouse skin to calculate a multiscale anisotropy factor to detect collagen fiber organization. Approach: The modified 2D WTMM anisotropy method was initially validated on synthetic calibration images to establish the robustness and sensitivity of the multiscale fiber organization tool. Upon validation, the algorithm was applied to collagen fiber organization in normal wild-type skin, melanoma stimulated skin, and integrin alpha 10KO skin. Results: Normal wild-type skin collagen fibers have an increased anisotropy factor at all sizes scales. Interestingly, the multiscale anisotropy differences highlight important dissimilarities between collagen fiber organization in normal wild-type skin, melanoma stimulated, and integrin alpha 10KO skin. At small scales (similar to 2 to 3 mu m), the integrin alpha 10KO skin was vastly different than normal skin (p-value similar to 10(-8)), whereas the melanoma stimulated skin was vastly different than normal at large scales (similar to 30 to 40 mu m, p-value similar to 10(-15)). Conclusions: This objective computational collagen fiber organization algorithm is sensitive to collagen fiber organization across multiple scales for effective exploration of collagen morphological alterations associated with melanoma and the lack of a10 integrin binding. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.

Automated summary

The study introduced a modified 2D wavelet transform modulus maxima anisotropy method to detect collagen fiber organization in different types of skin, revealing significant differences at multiple scales.