Medical MRI

Hardware, Software arid Areas of Application of Non-medical MRI 67... 

Multiple receive systems with multi-coil arrays have become widely distributed in medical MRI. The benefit is the enhancement of the signal-to-noise ratio per time or a reduction of the acquisition time. This technique is not used in NMR microscopy for objects of intermediate size in standard bore (52-mm id) and wide bore (89-mm id) magnets, which are the most widely distributed magnet types for NMR microscopy. The main reason is the restricted space in such magnets for the shim... 

Because the major cost of a commercial MRI is the magnet, there have been attempts to develop portable MRI consoles, that is, the requisite instrumentation for MRI minus the magnet, that could be transported to a medical MRI facility so that a scientific experiment could be set up independently of the medical MRI console (see Chapter 2.2). There are also efforts to develop compact NMR/MRI instruments for non-traditional uses. Granular studies would easily fit into this category. 

Clearly, it would be difficult at present to predict future development of the field, but the results already obtained leave no doubts that such applications are very promising. A great deal of further work is needed to develop these demonstrations into a practical set of tools for routine use, and the current pace of the progress in the field of non-medical MRI applications leaves no doubts that this goal can be achieved. 

Traditionally the technique of the medical physicist, magnetic resonance imaging (MRI) has long been used to investigate the internal structure of the human body and the transport processes occurring within it for example, MRI has been used to characterize drug transport within damaged tissue and blood flow within the circulatory system. It is therefore a natural extension of medical MRI to implement these techniques to study flow phenomena and chemical transformations within catalysts and catalytic reactors. 

Figure 3.55 Two commercial medical MRI systems, (a) Female patient being placed in the bore of the Toshiba EXCEL ART MRI system, (b) The four pole open magnet Toshiba OPART MRI system. (Photos courtesy of Toshiba America Medical Systems http //medical.toshiba.com.)...

The fact that the peak location of xenon in emulsion is approximately 100 ppm different from either gaseous xenon or xenon dissolved in blood or in tissue is a unique advantage for medical MRI. This could be exploited, for instance, for studying tumor vascularity by using hyperpo-... 

Imaging of solids (or other systems with very short T2 or T2 ) involves special techniques to overcome the need to encode spatial data very quickly. The approaches are not dissimilar to those of medical MRI, but the demands on the machine are more extreme, and the topic has developed a specialized scientific community of its own. 

Mobach, A.E. E. Toth, 7%e Chemistry of Contrast Agents in Medical MRI. 2001, Wiley, Chichester. 

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