Simultaneous and interleaved multinuclear chemical-shift imaging, a method for concurrent, localized spectroscopy

A method is proposed for carrying out chemical-shift imaging simultaneously on several nuclei (1H and 31P in this example), using a commercial clinical NMR imager fitted with a second RF channel and a dual-tuned birdcage coil to fit the human head. Nuclei of different gamma are examined at the same field of view by exciting each nucleus successively at times proportional to gamma during the same phase-encoding gradient waveform. Thus, each higher-gamma nucleus is exposed to a smaller area of the gradient. Additionally, since in vivo protons typically have a shorter T1 and roughly an order of magnitude higher sensitivity than phosphorus, it is possible to interleave 1H-only acquisitions between the simultaneous 1H, 31P observations while the lower-gamma nucleus relaxes. Consequently, additional information is obtained with either higher spatial resolution or greater sensitivity (more signal averaging) without lengthening the duration of the examination.