Hyperspectral imaging for monitoring oxygen saturation levels during normothermic kidney perfusion

Abstract

Abstract. The development of improved preservation techniques and the reliable assessment of donor grafts are main fields of research in transplantation medicine. Normothermic machine perfusion (NMP) is a promising alternative to static cold storage of organs, maintaining physiological conditions during preservation. In combination with NMP, we introduce hyperspectral imaging (HSI) as a novel approach for the monitoring of physiological kidney parameters. A line-scan HSI camera system was used to record images of porcine kidneys during NMP. Based on a dual-wavelength algorithm, the oxygen saturation levels were calculated from HSI recordings. Furthermore, we observed HSI images in the near-infrared (NIR) range in order to detect water characteristics of the kidney tissue. We found increasing levels of oxygenation during NMP and could discriminate between perfused and non-perfused areas. Cysts at the renal capsula were characterized by an absorption increase in the NIR band. Within this work, we showed that HSI is able to detect relevant chemical changes during NMP and allows the identification of pathologic variations.

Surgical spectral imaging

“…(2014) ; Kumashiro et al. (2016) Spatial Spectrograph 400–800 5–10 72 640 × 480 0.06–0.2 (~10–90 s) Colonoscopy, neurosurgery, gastroscopy Stomach, brain, bowel Tetschke et al. (2016) Spatial Spectrograph 500–1000 5 100–750 640 × 480 0.1 (40 s) Machine perfusion Kidney …”

“…Spatial scanning involves acquiring the spectral information from a single point (whisk-broom ( Qiu et al., 2010 )) or line (push-broom, Fig. 2 (c); ( Khoobehi et al., 2004 ; Clancy et al., 2016b ; Tetschke et al., 2016 )) and scanning across the field-of-view using galvanometer (galvo) mirrors or robotic actuation mechanisms ( Avila-Rencoret et al., 2015 ). Spectrometers and imaging spectrographs enable high spectral resolution (a few nm, band full-width at half-maximum (FWHM)) at hundreds of wavelengths.…”

“… Manufacturer Model Spectral resolution (nm) Spatial Resolution Bands Spectral Range (nm) Datacube Acquisition Time (s) Citing articles Diaspective Vision GmbH TIVITA (formerly TI-CAM) 5 640 × 480 100–750 500–1000 5 Holmer et al. (2016) ; Tetschke et al. (2016) ; Holmer et al.…”

“…More complex and physiologically-realistic optical properties can be achieved with multi-layer agar-based phantoms, with absorption and scattering properties set using India ink and intralipid, respectively ( Nishidate et al., 2011 , 2013 ). More relevant phantoms incorporate blood or haemoglobin, and include reference gas probes in tandem with temperature, pH, flow and oxygenation control ( Saito and Yamaguchi, 2015 ; Sakota et al., 2015 ; Tetschke et al., 2016 ; Gehrung et al., 2019 ). Realistic models include both solid and liquid elements, with simulated vessels running through an agarose tissue ( Luthman et al., 2018 ).…”

“… Lu and Fei (2014) describe the main approaches used to assemble the datacube, which may be broken down into scanning (either in the spatial or spectral dimensions) and snapshot (acquiring spatial and spectral information simultaneously) modalities. These spectral data can then be used to generate maps of tissue function ( Tetschke et al., 2016 ; Kawauchi et al., 2019 ), structural abnormalities ( Bedard et al., 2013 ) or enhanced contrast between different organs and structures ( Akbari et al., 2008a , 2008b ).…”