SIMULTANEOUS AND INTERLEAVED MULTINUCLEAR CHEMICAL-SHIFT IMAGING, A METHOD FOR CONCURRENT, LOCALIZED SPECTROSCOPY

A method is proposed for carrying out chemical-shift imaging simultane ously on several nuclei (H-1 and P-31 in this example), using a commer cial clinical NMR imager fitted with a second RF channel and a dual-tu ned birdcage coil to fit the human head. Nuclei of different gamma are examined at the same field of view by exciting each nucleus successiv ely at times proportional to gamma during the same phase-encoding grad ient waveform. Thus, each higher-gamma nucleus is exposed to a smaller area of the gradient. Additionally, since in vivo protons typically h ave a shorter T-1 and roughly an order of magnitude higher sensitivity than phosphorus, it is possible to interleave H-1-only acquisitions b etween the simultaneous H-1, P-31 observations while the lower-gamma n ucleus relaxes. Consequently, additional information is obtained with either higher spatial resolution or greater sensitivity (more signal a veraging) without lengthening the duration of the examination. (C) 199 4 Academic Press, Inc.