Imaging chemical shift contrast

Chemical shift contrast image and relaxation contrast image... 

Hyperpolarized 129Xe not only allows for sufficient signal intensity for chemical shift selective gas phase MRI, it also provides the means for a unique type of contrast. The imaging contrast derived from the transport of hyperpolarized gases into the material can be utilized to obtain snapshots of the gas flow and diffusion into porous samples. In this context, it is important to appreciate that Figures... 

The NMR-MOUSE is a portable NMR sensor which works in highly inhomogeneous magnetic fields. Because of field inhomogeneity NMR spectroscopy of the chemical shift is not readily possible, but relaxation times and parameters of translational motion can be measured by echo techniques. These are the most important NMR parameters which are exploited for contrast in imaging. Unless fluids are investigated field inhomogeneities are essentially no obstacle for relaxation analysis [80], because molecular motion by translational diffusion is absent. 

In CT, contrast occurs solely because of the attenuation of the X-ray beam by its interaction with tissue. Contrast in MRI depends on how the image is acquired. Proton density images reflect the different amounts of water content in different tissues. Chemical shift imaging can distinguish water from fat, based on the different chemical shifts of these protons. Contrast also can be altered in other ways by the exploitation of differences in water diffusion in tissue, by chemical exchange, and by magnetization transfer effects, to name a few. The majority of scans used clinically derive contrast from differences in the relaxation times Ti, T2, and T2. ... 

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