Method and system for NMR using RF pulses producing quadratic phase

A method of obtaining a NMR excited signal from a slab in a sample placed in a NMR system, comprising the steps of:

• providing an adiabatic RF excitation pulse capable producing a spatially varying phase that is substantially quadratic, and capable of producing a sharp slab profile and an excited signal in the slab;
• applying read- and phase-encoding gradients to the slab to spatially localize the excited signal;
• and
• detecting the excited signal.

A computer-readable medium having computer-executable instructions to cause a computer to perform a method of obtaining a NMR excited signal from a sample place in a NMR system, comprising the steps of:

• providing an adiabatic RF excitation pulse capable producing a spatially varying phase that is substantially quadratic and capable of producing a sharp slab profile and an excited signal in the slab;
• applying read- and phase-encoding gradients to the slab to spatially localize the excited signal;
• and
• detecting the excited signal.

In a computer having a processor, a method of forming an MRI image or NMR spectrum of a slab of a sample arranged in a NMR system, the method comprising:

• iteratively providing an adiabatic RF excitation pulse capable of forming a sharp slab profile to the slab;
• varying the phase-encoding gradient levels in each iteration to localize excited signals in the slab;
• detecting the excited signals;
• and
• in the processor, processing the excited signals to form the MRI image of the slab or the NMR spectrum of the slab.

A system for performing slab-select 3-D MRI or NMR spectroscopy of a slab in a sample, comprising:

• means for inducing NMR excitation in the slab that creates a substantially quadratic phase across the slab and that creates a sharp slab profile.
• means for detecting excited signals from the NMR excitation;
• and
• means for processing the excited signals to form a MRI image of the slab or a NMR spectrum of the slab.

A system for performing 3-D MRI or NMR spectroscopy of a slab of a sample, comprising:

• a magnet that creates a constant magnetic field within the slab;
• gradient coils capable of forming phase-encoding gradient magnetic fields within the slab;
• and
• one or more RF coils in operable communication with the slab and capable of providing thereto adiabatic RF excitation pulses capable of forming a sharp slab profile and a substantially quadratic phase across the slab, and detecting an excited signal from the slab.