A new type of MCA pulses combining constant and offset-independent adiabaticity for magnetic resonance

Adiabatic pulses are widely used in magnetic resonance techniques, and their development and refinement remain very relevant. Adiabatic inverting pulses are highly robust for radiofrequency or microwave magnetic field inhomogeneities and enable manipulation of spins over a large frequency range. In this work, new inverting pulses for spin 1/2 are proposed which combine the adiabaticity remaining constant for the single isochromat throughout the pulse and the same adiabaticity for all isochromats in a given bandwidth, but only at the single instant of time when the frequency of the pulse coincides with the frequency of the isochromat. The dependence of inversion performance of these pulses on peak amplitude of RF field, while preserving the pulse shape, is studied. These pulses may be useful for a number of MRI techniques where inverting pulses are an integral part. A comparison with other widely used adiabatic inverting pulses reveals performance improvements, achieving up to 30–40 % enhancement in inversion efficiency.