UPGRADE OF 47T IMAGING AND SPECTROSCOPY SYSTEM

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The availability of a short bore 4.7 T magnet makes possible a large number of experimental approaches for NIH funded grants in our laboratory and collaborating investigators. This application requests funds to purchase a set of shim and gradient coils for this magnet and to install a complete radiofrequency shield. The shield replaces our current practice of shielding each preparation and probe. The gradient and shim coils are physically separable so that the gradient coils can be removed when not needed allowing a larger diameter than available at present for some spectroscopic studies with larger animals. Thus the requested upgraded to our instrument greatly increases our flexibility and capabilities for our projects. These coils and shield are absolutely essential if currently funded human limb muscle projects are to utilize this instrument as planned. The reason is the distance from the magnet flange to the magnet center is 46 cm instead of the present 76 cm. The gradient strength will be increased more than 2-fold greater (10 G/cm instead of the present 4 G/cm) for improvements in capillary perfusion measurements, water suppression, and coherence transfer spectroscopy. These components will enhance the efficiency and productivity of all other projects using this instrument at our institution. Seven currently funded projects in three departments (Radiology, Bioengineering and Pediatrics) will benefit from the enhanced experimental improvements. Human limb muscle bioenergetics, biomechanics and perfusion studies (Kushmerick and Conley) will for the first time have access to a very high field instrument for their work with clear-cut improvements in resolution and signal to noise and in the ability to utilize more complex pulse sequences than is possible on the lower field Signa (1.5 T) instrument currently available to their work. Studies of in situ heats (Portman) and isolated perfused hearts (Kroll) and of muscle phenotype adaption by chronic AZT administration and other manipulations (Wiseman) will have greatly improved signal to noise because of the RF shield and increased access to their preparations within the bore of the magnet for physiological manipulations and control. The last project to benefit is a project in muscle modeling which will integrate flow and metabolism (Kushmerick) which is a major component in a funded NIH resource (Bassingthwaighte).