Rapid Quantitative Imaging of Heterogeneous Tissue Hemoglobin Dynamics Using Spatial Frequency Domain Imaging.

Area of Science:

• Biomedical optics
• Physiology
• Medical imaging

Background:

• Arterial insufficiency impacts chronic wounds, diabetes, and peripheral arterial disease, impairing vascular function.
• Accurate tissue oxygenation monitoring is crucial for vascular compromise assessment.
• Existing tools often lack wide-field imaging capabilities for heterogeneous tissue analysis.

Purpose of the Study:

• To evaluate spatial variation in tissue oxygenation during a vascular occlusion test (VOT).
• To compare oxygenation dynamics in microvascular versus macrovascular regions using wide-field imaging.
• To assess the utility of spatial frequency domain imaging (SFDI) for hemodynamic monitoring.

Main Methods:

• Spatial frequency domain imaging (SFDI) was used to map tissue oxygen saturation (StO₂) and hemoglobin concentrations (HbT1, HbT2).
• Vascular occlusion tests (VOT) were performed on 13 subjects.
• Two regions of interest (ROIs) were analyzed: macrovasculature and microvasculature (capillary networks).

Main Results:

• Significant differences in StO₂ were observed between microvascular and macrovascular ROIs at all time points.
• Microvascular ROIs exhibited greater StO₂ changes during occlusion, indicating higher oxygen extraction.
• No significant differences in HbT1 concentrations were found between ROIs.

Conclusions:

• Spatial variation is critical for accurate tissue hemodynamic assessment over time and across subjects.
• Wide-field SFDI enables evaluation of heterogeneous tissue regions, overcoming limitations of probe-based methods.
• Understanding spatial hemodynamics is vital for managing conditions associated with vascular compromise.