These gas vesicles are made of a porous wall structure through which noble gas could easily flow in and out. They can act like a fish’s swim bladder, enabling bacterial to control their buoyancy in water. To address this problem, researchers came up with contrast agents that are gas vesicles generated by specific bacteria. MRI sensitivity still remains low and it cannot detect many cellular biomarkers. However, to produce useful signals, MRI needs a high concentration of molecules which cannot be achieved with hyperpolarized xenon. New MRI contrast agent fills up with the harmless xenon gas | Credit: Barth van Rossum/FMP Improving MRI Sensitivity And since xenon is soluble in hydrophobic solvents and waters, hyperpolarized 129Xe could help physicians visualize a wide range of soft tissues. The hyperpolarized form of 129Xe can last up to several hours in the gaseous state. They used 129Xe (an isotope of xenon) to image cavities in porous samples, for example, gas flow within the lungs. Finally, they used the spin exchange process to transfer this polarization to nearby noble gas (xenon in this case) nuclei. Researchers pushed the electrons to higher energy levels and aligned (hyperpolarized) their spins with the help of a laser beam. Reference: ACS Nano | doi:10.1021/acsnano.8b04222 | Caltech | Physics World In this study, researchers created hyperpolarized xenon gas through an optical pumping method. To measure this chemical exchange with higher sensitivity, a technique called hyperpolarized nuclei is applied to different noble gases. Agents can be indirectly identified when they bind and exchange hydrogen atoms with water molecules present in the tissue. These agents contain targeting units that bind them to particular locations of cellular diseases. To enhance the MRI sensitivity, contrast agents are either inhaled or injected into the body. Unlike X-rays and ionizing radiation, MRI generates images of the body by exposing water molecules in the tissue to a strong magnetic field and magnetic field gradients, without harming the organs in the body. Recently, a research team at the California Institute of Technology developed a new kind of contrast agent for MRI that not only solves the issues of conventional contrast media but also configures itself to accommodate various amounts of hyperpolarized noble gas (xenon). Some of them, such as gadolinium-based MRI contrast agents, impose safety issues to some patients. However, the contrast agents (sometimes called dyes) used in MRI face two fundamental issues: they require high-concentrations and are extremely sensitive. It is used to detect anomalies in the brain and spinal cord, breast cancer, certain kinds of heart problems, and many other diseases. Magnetic resonance imaging (MRI) is a tomographic technique that uses a strong magnetic field and radio waves to construct detailed images of organs and tissues within the body. To do this, they created hyperpolarized xenon gas through an optical pumping method.Researchers develop a contrast agent that makes MRI more contrast and sensitive.
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