3D localized in vivo H-1 spectroscopy of human brain by using a hybrid of 1D-Hadamard with 2D chemical shift imaging

We report acquisition of 3D image-guided localized proton spectroscopy (H-1-MRS) in the human brain on a standard clinical imager. 3D coverage is achieved with a hybrid of chemical shift imaging (CSI) and transverse Hadamard spectroscopic imaging (HSI). 16 x 16 x 4 arrays of 3.5 and 1 ml voxels were obtained in 27 min. The spatially selective HSI 90 degrees pulses incorporate naturally into a PRESS double spin-echo sequence to subdivide the VOI into four partitions along its short axis. 2D GSI (16 x 16) is performed along the other long axes, Because the hybrid excites the spins in the entire VOI, a root N signal-to-noise-ratio (SNR) gain per given examination time is realized compared with sequentially interleaving N 2D slices. A two-told gain in sensitivity is demonstrated in the brain for N = 4.