Hadamard Encoded 3D MRSI of Human Brain at 7T
نویسندگان
چکیده
Introduction: At 7T in the human brain reduced RF amplitude and increased spectral dispersion result in chemical shift dispersion (CSD) artifacts that can distort metabolite ratios. For 2D encoding within the plane of a slice, CSD artifacts can be eliminated by replacing in-plane gradient based slab selective refocusing with RF shimming based outer volume suppression. However, for 3D acquisitions CSD artifacts during slab selection corrupts the most superior and inferior slices manifesting as artifactually large and small NAA/Cr ratios. Hadamard encoding in the slab direction minimizes this error by providing multiple thin slices with minimal CSD effects, increasing spatial overlap of the Cr and NAA volumes, thereby increasing the overlap of NAA and CR volumes from <40% (conventional 3D CSI) to 92.5%.
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