Investigation of MR Imaging With 64 Receiver Channels

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DESCRIPTION (provided by applicant): The objective of this project is to develop and characterize RF coil arrays for parallel MR Imaging at acceleration rates of up to 64 using a prototype 64 channel receiver system. Advances in gradient system and pulse sequence design have made dynamic MRI an important diagnostic tool. However, further increases in speed using conventional gradient based imaging appears limited by fundamental problems including gradient induced peripheral nerve stimulation and high RF power absorbtion rates. Parallel imaging, in which spatial localization is performed partially by the unique information contained in the reception patterns of an array of receiver coils, has become an important tool to reduce scan times without increasing gradient switching rates. These methods, known as SMASH, SENSE, SPACE-RIP and other variations, show great promise, but have only been explored to acceleration factors of 8, and 2 to 3 is more typical. This is partially due to the lack of availability of MRI systems with more than 8 receiver channels. In this project, planar and cylindrical array coils with 64 elements will be designed, fabricated and tested at the Magnetic Resonance Systems Lab on a 4.7 T scanner equipped with a 64 channel MRI receiver prototype that has been built and tested in the MRSL. Arrays will be characterized for SNR, artifact power and resolution at different levels of acceleration and imaging planes. An important feature of using the proposed large arrays is that the element size is on the order of the pixel, and differ from one another only by translation. Because of this, the point spread function of the array element itself can potentially be used to provide enhanced, or "superresolution". Superresolution techniques used in areas such as astronomical imaging and synthetic aperture radar will be investigated for their potential to provide improved spatial resolution, and sliding window techniques to provide improved spatial resolution with frame rates as high as one image per echo. both spatially and temporally, have the potential to provide improved resolution. The use of other resolution enhancement techniques including sliding window techniques will be investigated for imaging close to the array plane. It is expected that this project will advance our understanding of parallel MR imaging at very high frame rates, and provide researchers in this emerging field with data to test parallel imaging algorithms with more channels than previously available.