Evaluation of visible diffuse reflectance spectroscopy in liver tissue: validation of tissue saturations using extracorporeal circulation

Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period. Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for...

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Bibliographic Details
Published in:	Journal of biomedical optics Vol. 26; no. 5; p. 055002
Main Authors:	Voulgarelis, Stylianos, Fathi, Faraneh, Stucke, Astrid G, Daley, Kevin D, Kim, Joohyun, Zimmerman, Michael A, Hong, Johnny C, Starkey, Nicholas, Allen, Kenneth P, Yu, Bing
Format:	Journal Article
Language:	English
Published:	Society of Photo-Optical Instrumentation Engineers 01-05-2021
Subjects:	visible-light spectroscopy diffuse reflectance spectroscopy liver transplant tissue saturation
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Summary:	Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period. Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for measuring liver tissue saturation in vivo. Approach: A custom-built vis-DRS probe was calibrated using phantoms with hemoglobin (Hb) and polystyrene microspheres. Ex vivo (extracorporeal circulation) and in vivo protocols were used in a swine model (n = 15) with validation via blood gas analysis. Results: In vivo absorption and scattering measured by vis-DRS with and without biliverdin correction correlated closely between analyses. Lin’s concordance correlation coefficients are 0.991 for μa and 0.959 for μs ′ . Hb measured by blood test and vis-DRS with (R2 = 0.81) and without (R2 = 0.85) biliverdin correction were compared. Vis-DRS data obtained from the ex vivo protocol plotted against the PO2 derived from blood gas analysis showed a good fit for a Hill coefficient of 1.67 and P50 = 34 mmHg (R2 = 0.81). A conversion formula was developed to account for the systematic deviation, which resulted in a goodness-of-fit R2 = 0.76 with the expected oxygen dissociation curve. Conclusions: We show that vis-DRS allows for real-time measurement of liver tissue saturation, an indicator for liver perfusion and oxygen delivery.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Stylianos Voulgarelis and Faraneh Fathi contributed equally to the manuscript and are co-first authors.
ISSN:	1083-3668 1560-2281
DOI:	10.1117/1.JBO.26.5.055002