Hadamard Encoded 3D MRSI of Human Brain at 7T

Hoby Patrick Hetherington¹, Nikolai I Avdievich¹, Oded Gonen², Jullie W Pan¹

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. 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%.