? Scientists at the Center for Basic M.R. Research, Evanston, Illinois request partial funding support to purchase a 9.4T/305mm bore horizontal axis MR scanner to image rabbits, rats and mice. The imager will have actively shielded superconducting magnet and will be fitted with two integrated gradient -shim coils, dual channel RF transmitter and dual receiver system. The center has primary affiliation to Evanston Northwestern Healthcare and secondary affiliation to Northwestern University as a core facility of the Robert H. Lurie Cancer Center. Justification of the requested high field imager is based on the demand for higher spatial resolution, temporal resolution, signal to noise ratio and contrast to noise ratio in funded projects that cannot be met by the 4.7T imager currently in use. Support for the request is presented extensively in the form of data obtained at 4.7T and on a vertical axis Omega 400WB spectrometer that is no longer operational. Projects that will use the proposed imager are described under three sections based on the MR methodology employed: (i) functional imaging, (ii) diffusion tensor imaging, and (iii) novel approaches to contrast enhancement. Functional neuroimaging projects that use a conscious rabbit model include studies of learning, memory, aging, anesthesia and the relationship between BOLD fMRI and underlying neuronal activity. The 9.4T imager will benefit these projects by increasing BOLD contrast quadratically for small venuoles and capillaries with minimal contribution from the large vessels. The two-fold increase in SNR expected at 9.4T will allow structures in neuronal circuitry to be studied with greater spatial specificity. High spatial resolution on the order of 0.2mm3 or less is essential to study activation in structures such as cortical columns and cortical layers or those in the sensory-limbic-cerebellar system with specificity. Measurement of anisotropy by diffusion tensor imaging is employed by five projects to advance understanding of changes to the cellular environment in neurological disorders such as AD, ALS, MS, and hypoxia-ischemia. Anisotropy measurements in brain and spinal cord will greatly benefit from the increased SNR available at 9.4T since accuracy in these measurements is severely affected by poor SNR. High spatial resolution requirements in these studies which focus on substructures within gray and white matter compartments of the mouse spinal cord or CA1, CA3 and DG regions in mouse hippocampus can only be met by the increased sensitivity of the 9.4T imager. Research in the area of contrast agents focuses on developing target-specific agents to study cell migration and signaling and on overcoming limitations of paramagnetic agents at high magnetic fields. Strong institutional support for cost-sharing in the purchase of the imager is indicated. Scientific staff responsible for the instrument has expertise and experience in small animal imaging. ? ?
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