O-space imaging: highly efficient parallel imaging using complementary nonlinear encoding gradient fields and receive coil geometries

A magnetic resonance imaging method of performing parallel O-Space imaging comprising:

• performing, with a magnetic resonance imaging magnet system and an encircling circumferential array of RF imaging coils, an excitation of nuclear spins in an object;
• applying spatially-varying second-order nonlinear gradient encoding magnetic fields, which encodes the excited nuclear spins as a series of O-space imaging projections, with these encoded O-space imaging projections replacing conventional phase encoding;
• whereby each O-space imaging projection, is a projection onto a set of frequency isocontour rings that are concentric about different center placements (CPs) in a field of view (FOV) of the object;
• wherein the different center placements (CPs) correspond to successive echoes in an O-space imaging projection;
• and
• wherein these O-space imaging projections are a combination of Z2 spherical harmonic gradients along with X and Y linear gradients that functionally off set each O-space projection in an imaging plane, with the center of the Z2 spherical harmonic function being shifted off-center using the X and Y gradients for each echo encoded;
• optimizing the O-space imaging protections by using linear combinations of multiple spherical harmonics in order to form gradient shapes tailored so the gradient spatial encoding applied is complementary to the spatial encoding provided by the encircling circumferential array of RF imaging coils;
• measuring in parallel the received RF echo signals that are induced by the nuclear spins in the presence of the spatially-varying second-order nonlinear gradient encoding magnetic fields, of the Z2 spherical harmonics in the O-space imaging projections, by the encircling circumferential array of RF receiver coils;
• and
• reconstructing a magnetic resonance image, with the magnetic resonance imaging magnet system that is then provided and/or displayed.