? The broad goal of the research is to develop a new magnetic resonance imaging (MRI) contrast mechanism based on a quantity called the magnetic field correlation (MFC). The MFC is a measure of how the local magnetic field experienced by water molecules changes as the molecules diffuse through a biological tissue. The MFC can give, for example, information about the microscopic (cellular scale) distribution of iron in the brain, which may be useful in studying a variety of neurodegenerative pathologies, including Alzheimer's and Parkinson's diseases, that are associated with brain iron abnormalities. MFC imaging, when used in conjunction with a paramagnetic contrast agent, may also aid in evaluating tumors. Although the MFC is related to quantities, such as relaxation rates and diffusion constants that can be estimated with standard MR/techniques, there is currently no established method of determining the MFC. The contrast observed in an MFC image will differ from that obtained with standard MR/techniques, and MFC imaging can be regarded as providing a new contrast mechanism. The first phase of the research will be the implementation, optimization, and validation our proposed MFC imaging method. The validation will be accomplished by performing a series of imaging experiments with two types of synthetic models (phantoms). The phantom types will be aqueous suspensions, one with yeast cells and one with polystyrene microspheres. For both types, a paramagnetic contrast agent will be used to systematically adjust the magnetic field inhomogeneities. A careful comparison will be made between the acquired imaging data and the predictions of the theory upon which MFC imaging is based. For the polystyrene microsphere suspensions, the measured MFC can be compared directly, without the use of fitting parameters, to theoretically predicted values. The second phase of the research will demonstrate in vivo MFC imaging in 20 normal human subjects. For all the subjects, MFC images will be obtained of a brain slice containing the basal ganglia. The measured MFC values will be compared with model predictions based on histology and prior MR/studies. The means and standard deviations of the MFC values will be calculated for the subject pool. This will provide baseline data for the application of MFC imaging to neurological disorders. ? ?
