## 1 Introduction  
Organ transplantation often remains the last therapeutic option for patients affected by organ failure [1]. The increasing number of patients on the waiting list, the lack of donor organs, and the considerable discard rates for available organ transplants are major problems in transplantation medicine [2]. To address this issue, new strategies have been developed to make optimal use of the potential organ pool. One focus is the evaluation of organ quality ex vivo to predict organ function after implantation. Established clinical evaluation criteria, including histological features or donor characteristics considered in the Kidney Donor Risk Index, have their limitations and could not accurately predict organ function [3; 4; 5; 6]. Due to the current lack of a distinct objective standard, the decision to accept or reject organs often depends on the clinical experience of the transplant team. A promising approach to evaluate organ quality includes the measurement of biomarkers directly during preservation. While traditional static cold storage of the organ on ice offers only limited potential for assessing organ parameters, morphometric machine perfusion (NMP) has gained interest [7]. The objective underlying NMP is to maintain the organ's metabolism, thus its function by ensuring ex vivo oxygen and nutrient supply at physiological temperatures based on the perfusion with blood or a blood-based solution [8; 9; 10]. For kidneys, the analysis of hemodynamic characteristics, perfusate, urine, and tissue biomarkers during NMP offers the opportunity to evaluate graft injury and function [6; 11; 12]. Furthermore, a quality assessment score based on macroscopic appearance, blood flow, and urine output was established for clinical applications [13; 14; 15]. In these studies, it was demonstrated that NMP combined with an organ quality assessment tool can predict postoperative outcome. To enable a more comprehensive and primarily objective measurement of organ quality, additional injury and function markers should be included in the evaluation strategy [16]. One possibility could be the monitoring of ischemia/reperfusion injury (IRI)-induced markers, which occur due to the interruption of the oxygen supply to the organ with subsequent restoration of blood circulation. Numerous biochemical mechanisms are involved in the IRI, including adenosine triphosphate depletion, electrolyte imbalances, the formation of oxygen radicals, and changes in tissue water content (TWC) [17; 18]. The determination of certain selected parameters could significantly contribute to organ quality assessment prior to transplantation. In the medical field, hyperspectral imaging (HSI) has recently been applied to study physiological and pathological changes in both animal and human tissues. By combining imaging and spectroscopy, local information providing morphological features and spectral information characterizing the chemical composition of the tissue can be detected [19]. Emerging applications were diabetic foot analysis [20], retinal analysis in Alzheimer's disease [21], gastroenterological examinations [22], wound healing [23], and tumor detection [24]. Additionally, various tissue parameters were calculated from the HSI data, such as tissue oxygen saturation [25; 26], tissue hemoglobin index, near-infrared (NIR) perfusion index, or tissue water index (TWI) [27]. It is assumed that the TWI corresponds to the TWC. A first case study has shown that the TWC correlated with the function of NMP perfused kidneys [12]. Therefore, it is hypothesized that IRI-related mechanisms can be detected by TWC determination using non-invasive HSI images. In tissues, the TWI was used for the analysis of wound healing [28; 29; 30], scleroderma [31], intestinal perfusion deficits [32], [PERSON]'s disease of the hand [33], gastrointestinal anastomoses [34], ischemic conditions during esophagectomy, and in bowel loops [35; 36].