Relaxation time magnetic resonance imaging

Human skin is the largest organ in the human body. It is fundamentally important to health as the semi-permeable barrier - the first line of defence - between the body and the external world. However, it remains relatively inaccessible to conventional magnetic resonance imaging, firstly because it is thin and therefore requires high spatial resolution, and secondly because it is characterized by relatively short T2 relaxation times, particularly in the outermost stratum comeum. Conventional studies have not usually achieved a resolution better than 70-150 pm, with an echo time of the order of a millisecond or so. As a planar sample, skin has proved amenable to GARField study where it has been possible to use both a shorter echo time and achieve a better spatial resolution, albeit in one direction only. Such studies have attracted the interest of the pharmaceutical and cosmetic industries that are interested in skin hydration and the transport of creams and lotions across the skin. 

The use of magnetic resonance imaging (MRI) to study flow patterns in reactors as well as to perform spatially resolved spectroscopy is reviewed by Lynn Gladden, Michael Mantle, and Andrew Sederman (University of Cambridge). This method allows even unsteady-state processes to be studied because of the rapid data acquisition pulse sequence methods that can now be used. In addition, MRI can be used to study systems with short nuclear spin relaxation times—e.g., to study coke distribution in catalytic reactors. 

Chamuleau RA, Creyghton JH, De Nie I, et al. 1988. Is the magnetic resonance imaging proton spin-lattice relaxation time a reliable noninvasive parameter of developing liver fibrosis. Hepatology 8 217-221. 

Clearly, the basic imaging scheme can be extended to include relaxation-time contrast for discrimination of variations in cross-link density and strain, and the ID MRI-MOUSE (magnetic resonance imaging MOUSE) can be extended with further gradient coils to permit imaging in three dimensions. Numerous applications of the MRI-MOUSE can be envisioned in soft matter analysis, in particular in those areas, where imaging with conventional equipment has proven to be successful, and where smaller, less expensive, and mobile devices are in need. 

Andreasen NC, Ehrhardt JC, Swayze VW, Ii, Tyrrell G, Cohen G, et al. 1991. T1 and T2 relaxation times in schizophrenia as measured with magnetic resonance imaging. Schizophr Res 5 223-232. 

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