The investigators plan to prove the feasibility of receive-only phased array coil technology for human brain MR imaging studies at high field strengths (3T-4T). Such a coil will be unique in high field human applications. Improvements in brain imaging at 3T and 4T have been achieved without the benefit of the preferred method for high sensitivity imaging at lower fields: the use of volume coils for homogeneous excitation together with phased arrays of surface coils for high SNR reception. The desirability of this system stems from the combination of the homogeneous excitation provided by the volume coil and the unsurpassed sensitivity of phased array coil detectors. Our previous work developing these coils for neuroimaging at 1.5T has shown a 50-300 percent improvement in sensitivity compared to volume coil receivers for large region of the brain. The benefits are expected to be even greater at 3T and 4T since radiation losses at high frequency (with a frequency dependence approaching v^4) gives further motivation for the use of small surface coil arrays. The receive-only phased array coils proposed in this application will be developed for use with the high frequency homogeneous transmit coils which have already been developed by Nova Medical. Phase I of the current proposal will develop prototype phased array coils for neuroimaging, validate the active decoupling between transmit and receive subsystems and demonstrate the potential advantages of the system in sensitivity and regional coverage.
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