Abstract: Improved nuclei excitation for NMR applications is provided by employing a sequence of RF pulses for exciting the nuclei. Non-linearities in pulse excitation are compensated by applying at least one additional RF pulse thereby improving slice definition and/or phase characteristics. In one application, one or more initial RF pulses establish an intermediate state for the nuclei from which the nuclei can be tilted to a final desired magnetic moment state by the application of a single RF pulse. The order of applying the magnetic pulses can be reversed when the flip/angle is 180 degrees.

Abstract: A method of collecting image data with selective spectral suppression for at least two species is provided. A sequence of RF excitation pulses is repeatedly applied, whereby a repeated sequence of at least two substantially different spectrally selective steady-state magnetizations is established. Magnetic gradients are applied between said RF pulses. A plurality of magnetic resonance image (MRI) signals is acquired. The plurality of MRI signals is combined using a weighted combination where the weights depend on a control parameter that adjusts a trade-off between selective spectral suppression and signal-to-noise ratio (SNR).

Abstract: Multiple inversion recovery flow imaging employs at least four spin inversion pulses following saturation of static nuclei spins to null nuclei in static material having different spin-lattice relaxation times (T.sub.1) with the inversion pulses being spaced in time to substantially reduce the longitudinal magnetization of the T.sub.1 species present. The saturation of static nuclei spins includes applying a sequence of saturation pulses with adjacent pulses being separated by a diphasing gradient to avoid refocusing coherence. The detection of signals includes applying at least one RF read-out pulse near the nulling point.