A Comparative Evaluation of EPR and OxyLite Oximetry Using a Random Sampling of PO(2) in a Murine Tumor
Overview
Affiliations
Methods currently available for the measurement of oxygen concentrations (oximetry) in viable tissues differ widely from each other in their methodological basis and applicability. The goal of this study was to compare two novel methods, particulate-based electron paramagnetic resonance (EPR) and OxyLite oximetry, in an experimental tumor model. EPR oximetry uses implantable paramagnetic particulates, whereas OxyLite uses fluorescent probes affixed on a fiber-optic cable. C3H mice were transplanted with radiation-induced fibrosarcoma (RIF-1) tumors in their hind limbs. Lithium phthalocyanine (LiPc) microcrystals were used as EPR probes. The pO(2) measurements were taken from random locations at a depth of approximately 3 mm within the tumor either immediately or 48 h after implantation of LiPc. Both methods revealed significant hypoxia in the tumor. However, there were striking differences between the EPR and OxyLite readings. The differences were attributed to the volume of tissue under examination and the effect of needle invasion at the site of measurement. This study recognizes the unique benefits of EPR oximetry in terms of robustness, repeatability and minimal invasiveness.
The Role of Imaging Biomarkers to Guide Pharmacological Interventions Targeting Tumor Hypoxia.
Gallez B Front Pharmacol. 2022; 13:853568.
PMID: 35910347 PMC: 9335493. DOI: 10.3389/fphar.2022.853568.
The clinical utility of imaging methods used to measure hypoxia in cervical cancer.
Waller J, Onderdonk B, Flood A, Swartz H, Shah J, Shah A Br J Radiol. 2020; 93(1111):20190640.
PMID: 32286849 PMC: 7336054. DOI: 10.1259/bjr.20190640.
Dynamic EPR Oximetry of Changes in Intracerebral Oxygen Tension During Induced Thromboembolism.
Hou H, Khan N, Gohain S, Eskey C, Moodie K, Maurer K Cell Biochem Biophys. 2017; 75(3-4):285-294.
PMID: 28434138 PMC: 5651212. DOI: 10.1007/s12013-017-0798-1.
A review of flux considerations for in vivo neurochemical measurements.
Paul D, Stenken J Analyst. 2015; 140(11):3709-30.
PMID: 25977941 PMC: 5310531. DOI: 10.1039/c4an01898b.
Clinical EPR: unique opportunities and some challenges.
Swartz H, Williams B, Zaki B, Hartford A, Jarvis L, Chen E Acad Radiol. 2014; 21(2):197-206.
PMID: 24439333 PMC: 3921887. DOI: 10.1016/j.acra.2013.10.011.