We have developed a technique called polarized spatial frequency domain imaging (pSFDI) to noninvasively image fiber orientation and alignment in tissues with highly aligned structure such as heart valve leaflets. This reflectance-based technique does not require tissue processing (e.g. fixation or clearing) and can be performed dynamically while tissues are being mechanically loaded.
Goth W, Potter S, Allen A, Zolden J, Sacks MS, Tunnell JW. Non-destructive reflectance mapping of fiber alignment in multi-layered tissues. Ann Biomed Engineering 47 (5), 1250-1264, 2019 https://doi.org/10.1007/s10439-019-02233-0
Yang B, Sharma M, Lesicko J, Sacks M, Tunnell JW. Polarized Light Spatial Frequency Domain Imaging for Non-Destructive Quantification of Soft Tissue Fibrous Structures. Biomed Opt Express, 6:1520–1533, 2015 https://doi.org/10.1364/BOE.6.001520