A novel Electron Paramagnetic Resonance (EPR) oximetry
technique will help clinicians directly measure oxygen and schedule treatments
at times of high oxygen levels in cancer and stroke patients to improve outcomes,
the EPR team at Dartmouth's Geisel School of Medicine has found.
The team, led by
Harold Swartz, MD, PhD, published their groundbreaking progress on the
decades-old conundrum of how to measure oxygenation in deep-sited tissue in a
paper titled, 'Deep-Tissue Oxygen Monitoring in the Brain of Rabbits for Stroke
Research,' published in Stroke.
Nadeem Khan, PhD,
first author said, "This is a major step forward. It brings EPR oximetry
technique to the forefront of biomedical research for clinical applications."
Oxygen is necessary
to sustain life. A certain level of oxygen in a cell or tissue is necessary to
maintain the generation of energy by cells. Oxygen also plays a key role in the
development and treatment of various diseases.
The effectiveness of
several therapies also depends on the oxygen levels in a malignancy. For
example, a very low level of oxygen in cancer is known to develop aggressive
phenotypes, varies with the growth of tumors, and also compromises the
effectiveness of chemotherapy and radiation. Hence, it is very important to
directly measure oxygen levels to understand disease progression, develop
strategies to improve oxygen levels, and optimize the efficacy of therapies.
in deep-sited tissue has been a challenge for several techniques, which has
unfortunately limited the understanding of various pathologies in large animals
and humans. To solve the problem, Dartmouth's EPR team developed implantable
resonators made of thin nonmagnetic copper wire to facilitate direct and
repeated measurement of tissue oxygenation at any depth from the surface. In
their most recent experiment, which demonstrated the efficacy of in vivo EPR
oximetry, they used a one-time implementation of the oxygen probes in the brain
of a rabbit and successfully monitored oxygen levels for several weeks.
"Other than the
implantation, which is done under anesthesia, the rest of the procedure for
oxygen measurements is entirely non-invasive. We anticipate that a better
understanding of oxygen levels in stroke, for instance, will guide the
development of strategies to significantly improve oxygen levels in the
ischemic regions of the brain and thereby improve outcomes," explained
conclude that real-time monitoring of tissue oxygenation using implantable
resonators will be a powerful tool in stroke and cancer research.