Abstract
Hypoxia occurs in various pathophysiological conditions. Especially, brain can be seriously affected by the oxygen deficiency. However, challenges exist in optically monitoring cerebral hemodynamics with high resolution. As an easily-detected vessel bed, peripheral skin is a potential target for predicting cerebrovascular hemodynamic changes. However, the similarities and differences between cerebral and cutaneous hemodynamics during hypoxia are still unclear. One of the main reasons is that optical imaging techniques are fundamentally depth/resolution-limited due to high scattering properties of turbid tissue. Fortunately, in vivo tissue optical clearing techniques can efficiently overcome these problems, and avoid the side-effects of surgical windows. In this work, we simultaneously monitor the changes in cortical and cutaneous microvascular blood oxygen and blood flow under the assistance of in vivo skull and skin optical clearing techniques, and quantitatively compared the differences between cerebral and cutaneous arteriovenous functional responses to the hypoxic stimulus. The results indicated that the variation tendency of blood oxygen response might be more similar, and cutaneous vascular blood oxygen response has the potential to serve as an accessible indicator for revealing cerebrovascular dysfunction. Moreover, it provides a feasible approach to realize visualization of in vivo monitoring cerebral and cutaneous microvascular reactivity with minimal invasiveness.
Highlights
T ISSUE hypoxia plays an important role in the pathophysiology of various human disorders, e.g., ischemic cardiovascular disease, stroke, chronic lung disease, acute skin woundsManuscript received October 15, 2020; revised January 22, 2021; accepted February 22, 2021
The cortical and cutaneous microvascular SO2 and blood flow velocity maps could be obtained with the high resolution (Fig. 2(a))
The results showed that the skin microvascular blood oxygen response was similar with the cortical microvessels under the hypoxic stimulus, but there were some differences between skin and brain microvessels in the trend of blood flow
Summary
T ISSUE hypoxia plays an important role in the pathophysiology of various human disorders, e.g., ischemic cardiovascular disease, stroke, chronic lung disease, acute skin woundsManuscript received October 15, 2020; revised January 22, 2021; accepted February 22, 2021. T ISSUE hypoxia plays an important role in the pathophysiology of various human disorders, e.g., ischemic cardiovascular disease, stroke, chronic lung disease, acute skin wounds. Date of publication February 26, 2021; date of current version March 30, 2021. The hypoxia has an effect on other tissues and organs including peripheral skin [7]. There have been some researches investigate the changes in blood flow or blood oxygen of brain and skin by using various techniques, i.e., Duong et al employed MRI to monitor the cerebral blood flow velocity changes induced by hypoxia [8]; Palmer et al used spectral imaging to investigate the cutaneous blood oxygen changes around the tumor [9]. The imaging resolutions of these approaches have been greatly limited
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