Quantitative MRI Oximetry: Combining EPR and OE-MRI for Volumetric Mapping of Hypoxia in Tumors

Motivation: This study is driven by the need for a reliable method to correlate R1 maps from Oxygen-Enhanced MRI (OE-MRI) with absolute hypoxia levels in tumors, to improve outcomes in MR-guided radiation treatment. Goal(s): The aim is utilize electron paramagnetic resonance (EPR) Oximetry to develop a calibration curve between R1 and pO2. Approach: Using a solid tumor model with two implanted EPR probes, OE-MRI was conducted at 21% and 100% oxygen to gather data for calibration. Results: The correlation between OE-MRI R1 data and EPR Oximetry provided a viable hypoxia map, which could be used to increase the efficacy of MR-guided radiation therapy. Impact: This study investigates a calibration method, which could act as a quality assessment tool for the hypoxia maps generated using OE-MRI, potentially improving personalized cancer treatments.