Clinical electron paramagnetic resonance (EPR) oximetry using India ink

Area of Science:

• Biomedical Engineering
• Medical Physics
• Oncology

Background:

• Direct measurement of tissue partial pressure of oxygen (pO(2)) is crucial for managing oxygen-dependent diseases and therapies.
• Existing methods for tissue oximetry have limitations in accuracy and invasiveness.
• Electron paramagnetic resonance (EPR) oximetry offers a non-invasive approach for absolute pO(2) quantification.

Purpose of the Study:

• To evaluate the feasibility and clinical utility of EPR oximetry for measuring subcutaneous and tumor pO(2) in human subjects.
• To demonstrate the potential of EPR oximetry in guiding and optimizing oxygen-dependent therapies.
• To establish EPR oximetry as a tool for characterizing disease status and therapeutic response.

Main Methods:

• Utilized low-frequency (1.2 GHz) EPR spectroscopy with surface loop resonators for in vivo measurements.
• Employed India ink as an oxygen reporter for absolute pO(2) quantification.
• Conducted studies in healthy volunteers (subcutaneous foot tissue) and cancer patients (tumor tissues).

Main Results:

• Successfully performed repeatable, non-invasive EPR oximetry measurements in superficial tissues.
• Demonstrated feasibility of tumor oximetry in patients undergoing radiation and chemotherapy for various cancer types.
• Collected longitudinal data, with some measurements spanning up to 5 years, showcasing reliability.

Conclusions:

• EPR oximetry is a feasible technique for clinical application, providing quantitative tissue pO(2) measurements.
• This method has the potential to significantly aid in the characterization of diseases and optimization of oxygen-dependent treatments.
• Wider adoption of EPR oximetry could enhance clinical outcomes for patients with various oxygen-dependent conditions.