Metabolic Lesions in Focal Epilepsy Studied by MRI and Spectroscopy (Whitaker Foundation) Introduction: Up to 20% of focal epilepsy patients (about 400,000 in the USA) fail to respond to anti-epileptic medication. Fewer than one-third of these refractory patients are currently considered candidates for the highly effective surgery to resect the seizure focus because the presurgical evaluation is costly, inaccurate, and often invasive (thus risky). It is also thought that seizures may induce secondary neuronal dysfunction in brain tissue remote from the primary seizure focus. Methods: Using quantitative MRSI (Core Project I) and MRI (Core Project IV) methods, determine the optimal combination of MR measures for localization of the epileptogenic seizure focus. Results: Early studies indicate that a combination of 1H MRSI and relaxometry is highly sensitive and specific. In patients whose seizures are eliminated by surgery, recovery of normal metabolism and MRI measures has been observed one year after surgery in tissue with secondary neuronal dysfunction detected before the surgery. Discussion: The high sensitivity and specificity of noninvasive MRSI and MRI for localization of the epileptogenic seizure focus could reduce the cost and risk of presurgical evaluation and could qualify more refractory patients for effective surgical treatment. When the head gradient coil and rapid imaging are implemented (Core Projects IV and II), then volumetry, diffusion, and perfusion measurements at 4.1T will be routinely included in the protocol. From this full MR protocol, an optimal combination will be determined.