Brain edema has been extensively studied through ultrastructural and chemical investigations over the past decade. Recently, nuclear magnetic resonance (NMR) spectroscopy has been used to study the molecular aspects of brain edema and NMR imaging has been introduced as a tool to study the entire brain in vivo. NMR imaging is in its infant stage and information is lacking in regard to its ability to quantitate brain edema or to define different types of edema based upon longitudinal (T1) and transvers (T2) relaxation values or image intensities. Questions arise as to how early can the appearance of edema be detected by NMR imaging, what role do the hydrogen protons of liberated brain lipids in brain edema play in NMR imaging, and how well do NMR imager T1 and T2 values correlate with T1 + T2 values obtained by a high resolution NMR spectromter in the study of the same tissue sample? T1 and T2 relaxation values of sodium ions of edema fluid and the phosphorus of liberated membrane lipids in brain edema can be investigated by high resolution NMR spectroscopy relative to normal brain tissue and their alterations may be of significance in brain edema.
The aims of this proposal are to provide answers to these questions by studying brain edema in animal models of impact brain injury, infarct, cold lesion, brain tumor, and brain abscess with NMR imaging, high resolution NMR spectroscopy of hydrogen protons, sodium and phosphorus, microgravimetry and wet/dry weights, cerebral blood volume determination, brain phospholipid and free fatty acid assays, and histologic examination of edematous brain tissue. The long term goals of this proposal are to achieve a better understanding of brain edema, to make the NMR imager a more understandable and useful diagnostic tool, and to expand the horizons of NMR scanning to include sodium and phosphorus nuclei as a basis for imaging.
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