Epilepsy is one of the most common neurological disorders, affecting one to two million Americans. For some 100,000-200,000 Americans its debilitating symptoms cannot be overcome through medication. In some of these patients, surgery is highly effective, however available non-invasive diagnostic procedures such as MRI, PET and scalp EEG provide diagnostic localization in less than 70 percent of the patients with partial seizures. Intracranial EEG measurements while highly accurate are invasive, require hospitalization and are costly. However MR spectroscopy examinations using the ratio of N-acetyl aspartate (NA)/creatine (CR) have recently proven to be highly effective in lateralizing epileptogenic tissue. These studies have used asymmetries in the NA/CR ratio between the temporal lobes as the criteria for determining the seizure focus. Unfortunately this type of analysis precludes the use of this test to: 1) evaluate the patient for evidence of bilateral disease, 2) determine the spatial extent of the disease and 3) determine which compounds are actually changing (CR or NA or both). Therefore the goal of this proposal is to: 1) extend, apply and evaluate 1H CSI methods which permit the localization of the seizure focus based on absolute comparisons to parameters determined from healthy tissue, thereby permitting evaluation of the presence of bilateral disease; 2) determine the origin of the ratio changes seen 3) evaluate the use of other metabolic parameters, specifically glutamate and glutamine content as indicators for the localization of the seizure focus and 4) evaluate the sensitivity and specificity of these methods in comparison to scalp EEG and MRI at 1.5T. These studies will be performed at 4.1T on a whole body imaging/spectroscopy system. Although the number of these systems are extremely limited, the advantages in terms of increased S/N, spatial resolution and spectral resolution, makes it an attractive tool for investigating these changes. Successful validation of this methodology and its subsequent translation to lower field strengths, would provide a highly accurate, non-invasive and cost effective mechanism for pre- surgical planning.
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