QUANTITATIVE 3D BRAIN MRSI WITH PHASED ARRAY ACQUISITION

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Brain 1H magnetic resonance spectroscopic imaging (MRSI) has been shown to have significant diagnostic and treatment assessment value. To achieve the goals of short imaging times and robust quantification, we implemented a 3D MRSI sequence at 1.5T with dualband spectral-spatial excitation, spiral k-space readout, 8-channel phased-array acquisition, voxel-by-voxel phasing and automated quantification. Methods and Discussion: A spectral-spatial 90 degree RF pulse and two identical dualband spectral-spatial 180 degree pulses were incorporated into a PRESS sequence to form a spin echo. The 90 degree pulse is designed to fully excite both water and metabolites and the dualband 180 pulse is designed to fully excite metabolites resonances from Choline to NAA, partially excite water, while suppressing lipids signals. During readout, spirals with 4 interleaves were played out for spatial and spectral encoding. The final imaging sequence has the following characteristics: outer volume suppression, dualband spectral-spatial PRESS excitation, partial water suppression, 32/32/16 matrix size, 1cc voxels, and 13 minute acquisition time at 1.5T. The signal from each of the 8 RF coils was reconstructed independently. Phased spectra for each voxel from each coil were combined according to water peak values to achieve maximum SNR. Spectra were then passed to the LCModel software package for quantification. Acknowledgements: Lucas foundation, NIH RR 09784, CA 48269