Frequently Asked Questions

Oxygen is the most important molecule to sustain life. Cells survive and thrive in a precise oxygen environment, and low oxygen or hypoxia is a hallmark of many pathologies.

Hypoxia is known to be an impediment to the success of radiation therapy in cancer. By mapping partial oxygen pressure (pO₂) maps, one can choose which areas require higher radiation dose (e.g., HF10 or below) and avoid the areas which does not require higher dose, thus reducing the overall radiation dose and post-care complications.

Yes, oxygen is important in many pathologies and is an effective response to treatment. Knowledge of oxygen can improve therapies in type I diabetes, cell and gene therapy, neurological disease, wound healing, ischemia, kidney pathologies, blood transfusion, organ preservation, etc.

Triarylmethyl (trityl) OXO71-based electron paramagnetic resonance (EPR) oxygen imaging (EPROI) is the leading and only modality that provides quantitative partial oxygen pressure (pO₂) maps in tissue. EPROI is suitable for in vitro and in vivo pO₂ imaging.

EPR is a magnetic resonance technique that detects unpaired electron spins placed under a constant uniform magnetic field, manipulated by pulse radiofrequency electromagnetic radiation. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944. The technology is similar to MRI principles.

EPR oxygen imaging (EPROI) is an established noninvasive method to map absolute oxygen. EPROI measures electron spin-lattice relaxation rate (R₁) maps of a water-soluble oxygen-reporting trityl OXO71 molecule. The linear relationship between pO₂ and trityl relaxation rate, along with spatial mapping techniques similar to MRI, is utilized for 3D pO₂ imaging.

Being EPR uniquely sensitive to unpaired electrons, it allows us to probe paramagnetic species and their environment. In addition to oxygen, EPR probes can also sense local pH, redox potential, inorganic phosphate, etc.

Blood oxygen level dependent (BOLD) MRI is a qualitative (not quantitative) technique to probe pO₂. BOLD reports on changes in the relaxation rate R₂* of blood as a response to a change in the oxygen demand. It does not provide quantitative pO₂ maps.  

Positron emission tomography (PET) with hypoxia-sensitive tracers, such as ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO), only provides assessment of hypoxia in cells, and does not provide 3D pO2 maps in the full physiological range. In contrast, EPROI provides pO₂ maps between 0 % O₂ (0 torr) and 21% O₂ (160 torr) in the extracellular space.

Oxygen imaging is distinct from pulse oximetry, polarographic electrodes, or oxygen-quenching luminescence sensors, which provide single-point pO₂ values at the location of the probe and do not provide 3D pO₂ maps.

JIVA-25® is a first-of-its-kind preclinical oxygen imager, based on EPROI. JIVA-25® provides three-dimensional oxygen maps of tissues, in vitro and in rodents. Biomaterial samples, cell encapsulation devices, artificial tissue grafts, ex vivo rodent organs, and rodents can be imaged with JIVA-25®. 

JIVA-25® provides both average oxygen over the sample volume as well as three-dimensional oxygen maps of the sample volume.

Yes. JIVA-25® can measure oxygen in various biomaterials so long as there is no paramagnetic component. The examples include, but are not limited to, gelatin, agarose, alginate, etc.

Samples can be as small as cells in a well or as large as a mouse or a small rat.

JIVA-25® is not suitable for oxygen imaging in humans.

25 millitesla (mT).

You can read publications utilizing JIVA-25® here.

JIVA-25® standard protocol for acquiring a 3D oxygen map lasts 10 minutes. Acquisition time can be reduced to 2 minutes, at the expense of T1 measurement precision and/or image resolution.

For samples within 40x32 mm, JIVA-25® features volumetric resonators, so penetration depth does not have an impact on accuracy and sensitivity in this case.