3D localized in vivo 1 H 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 ( 1 H‐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 × 16 × 4 arrays of 3.5 and 1 ml voxels were obtained in 27 min. The spatially selective HSI 90° pulses incorporate naturally into a PRESS double spin‐echo sequence to subdivide the VOI into four partitions along its short axis. 2D CSI (16 × 16) is performed along the other long axes. Because the hybrid excites the spins in the entire VOI, a √ N signal‐to‐noise‐ratio (SNR) gain per given examination time is realized compared with sequentially interleaving N 2D slices. A two‐fold gain in sensitivity is demonstrated in the brain for N = 4.