Pre-Transplantation Evaluation of Human Liver Using Polarization-Sensitive Optical Coherence Tomography

Introduction:: Human liver transplantation is a standard treatment for certain hepatic cancers and advanced-stage liver chronic diseases. With the massive request for liver transplantation, challenges and difficulties come up with donor quality assessment, recipient selection, immunosuppression, and infectious complications. Monoethyl-glycinexylidide (MEGX) is a primary method to make a dynamic test of liver function for the transplantation. However, this test is invasive and always be affected by gender and other drugs in the donor. To further confirm the quality of donor livers, histopathology is the current gold-standard to assess the donor liver through evaluating the allograft diseases and other tissues for infections to provide the suitability of the donor liver for transplantation. Unfortunately, due to the invasiveness and limited sampling volume of the biopsy, studies have shown controversies in the utility of procurement biopsies for evaluating donor livers. Therefore, there is a critical need to explore new noninvasive ways to predict transplant liver viability through.

Materials and Methods:: >1500 sampling locations from 15 human livers with different ages and genders were imaged using a polarization-sensitive optical coherence tomography (PS-OCT) system. Two-dimensional (2D) and three-dimensional (3D) imaging modes were used to provide cross-sectional, enface, and spatial information of the livers for distinguishing and localizing the distribution of different microstructures and tissues. Three polarization parameters (phase retardation, optic axis direction, and degree of polarization uniformity-DOPU) and three Stokes parameters (Q, U, and V) were utilized for multi-parameter image analyses and quantification. After OCT imaging, each sampling location was biopsied and processed by both standard and special histological staining. The histological score for each biopsied tissue was graded by a board-certified pathologist. The commonly used histology scoring system was used as the gold standard to quantify the performance of PS-OCT in pre-transplantation liver quality evaluation.

Results, Conclusions, and Discussions:: In this study, we observed that globules, steatosis, necrosis, and granuloma, etc. in 2D cross-sectional and enface dimensions were clearly differentiated in PS-OCT structure images, which were consistent with conventional histological images. With the histological staining providing the spatial structure and tissue distribution of liver tissues as the golden standard, PS-OCT precisely identified the fibrosis and collagen and showed the corresponding distributions based on polarization and Stokes parameters in the enface slices at different locations and depths within the whole liver. We found that the distribution and change of microstructures and functional tissues were ununiform and heterogenous within the whole liver, which resulted a big difference in evaluations from different locations on the liver if using biopsy. Compared to the conventional sole biopsy method, PS-OCT was able to noninvasively provide microstructure information and tissue distribution characteristics throughout the whole liver to offer a comprehensive evaluation of pre-transplantation livers. PS-OCT effectively provided evaluation and quantification information on liver microstructure and tissue distributions within human livers using polarization and Stokes parameters, which precisely distinguished and quantified changes in structures and tissues at different locations from the whole liver to offer a comprehensive evaluation of the pre-transplantation liver quality. Our results demonstrated that PS-OCT was promising to provide noninvasively quantitative evaluation of pre-transplantation throughout the whole human liver and had the potential to be used as a tool in transplant clinics.

Acknowledgements (Optional): : This work was supported by grants from the University of Oklahoma Health Sciences Center (3P30CA225520), Faculty Investment Program from University of Oklahoma, Institutional Research Grant number IRG-19-142-01 from the American Cancer Society, National Science Foundation (OIA-2132161, 2238648), National Institute of Health (R01DK133717), Oklahoma Shared Clinical and Translational Resources (NIGMS U54GM104938), Oklahoma Center for the Advancement of Science and Technology (HR23-071), and the medical imaging COBRE (P20 GM135009). Histology service provided by the Tissue Pathology Shared Resource was supported in part by the National Institute of General Medical Sciences COBRE Grant P20GM103639 and National Cancer Institute Grant P30CA225520 of the National Institutes of Health.

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