HIGH-SPEED H-1 SPECTROSCOPIC IMAGING IN HUMAN BRAIN BY ECHO-PLANAR SPATIAL-SPECTRAL ENCODING

We introduce a fast and robust spatial-spectral encoding method, which enables acquisition of high resolution short echo time (13 ms) proton spectroscopic images from human brain with acquisition times as short as 64 s when using surface coils. The encoding scheme, which was impl emented on a clinical 1.5 Tesla whole body scanner, is a modification of an echo-planar spectroscopic imaging method originally proposed by Mansfield Magn. Reson. Med. 1, 370-386 (1984), and utilizes a series o f read-out gradients to simultaneously encode spatial and spectral inf ormation. Superficial lipid signals are suppressed by a novel double o uter volume suppression along the contours of the brain. The spectral resolution and the signal-to-noise per unit time and unit volume from resonances such as N-acetyl aspartate, choline, creatine, and inositol are comparable with those obtained with conventional methods. The sho rt encoding time of this technique enhances the flexibility of in vivo spectroscopic imaging by reducing motion artifacts and allowing acqui sition of multiple data sets with different parameter settings.