Near infrared spectroscopy system for quantitative monitoring of renal hemodynamics and oxygenation in rats

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Item Type:	Conference or Workshop Item
Title:	Near infrared spectroscopy system for quantitative monitoring of renal hemodynamics and oxygenation in rats
Creators Name:	Gladytz, T., Hoppe, A., Cantow, K., Flemming, B., Pohlmann, A., Niendorf, T., Seeliger, E. and Grosenick, D.
Abstract:	Regulation of renal hemodynamics and oxygenation is complex and its detailed understanding is crucial to improve therapeutic procedures for kidney diseases like acute kidney injury. For the challenging task of monitoring renal hemodynamics and oxygenation in rats, we designed a continuous wave (cw) multispectral near-infrared spectroscopy setup. A fiber probe with a source fiber and eight detection fibers is placed on the ventral surface of the exposed rat kidney in vivo, and an additional source fiber is positioned on the dorsal surface. Nine wavelengths from 658 nm to 1060 nm are used to have sufficient redundancy for reliable quantification of hemoglobin concentration, oxygen saturation of hemoglobin, and tissue water content. To investigate both, the surface layer and deeper tissues, the setup alternates between reflection and transmission at a rate of 10 Hz. Our system relies on spatially resolved reflection and transmission, and multispectral analysis to differentiate absorption from scattering. Monte-Carlo Simulations for a layered tissue structure are used as a model for quantitative characterization of the renal cortex and medulla. Renal parameters are monitored during baseline conditions and during dedicated pathophysiologically relevant interventions including arterial occlusion and changes of inspiratory gas mixture. Together with invasive probes, which monitor arterial blood pressure, renal perfusion and tissue oxygenation, a detailed picture of renal hemodynamics and oxygenation in several pathophysiological conditions is acquired. This detailed information can serve as a quantitative reference to other methods such as MRI.
Keywords:	Renal Hemodynamics, Oxygenation, Near-Infrared Spectroscopy, Tissue Optical Properties, Animals, Rats
Source:	Proceedings of SPIE
Series Name:	Proceedings of SPIE
Title of Book:	Optical Tomography and Spectroscopy of Tissue XIII
ISSN:	0277-786X
Publisher:	International Society for Optics and Photonics (SPIE)
Volume:	10874
Page Range:	108970H
Date:	1 March 2019
Official Publication:	https://doi.org/10.1117/12.2507371

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