Apparatus and method for magnetic resonance imaging using partial parallel acquisition (PPA)

An apparatus for magnetic resonance imaging using partial parallel acquisition for projection reconstruction comprising:

• a magnetic resonance scanner including an RF system for exciting nuclear spins in a subject and acquiring radiofrequency signals arising from the excited nuclear spins in a plurality of projection datasets, with a plurality of reception coils having respective sensitivity profiles, and a gradient system which generates a readout gradient under which said projection datasets are read out for entry into k-space;
• a control unit for operating said scanner to under-scan k-space with said coils and form a complete projection dataset by progressively rotating said readout gradient through successive fixed step angles;
• an image computer supplied with said projection dataset for producing a Cartesian resultant dataset by transforming said projection dataset in k-space onto grid points of a first Cartesian grid with a first grid constant;
• said image computer producing a Cartesian reference dataset by transforming a central region of the projection dataset in k-space onto a second Cartesian grid having a second grid constant that is smaller than said first grid constant;
• said image computer calculating the respective sensitivity profiles of said coils from said reference dataset;
• and
• said image computer reconstructing a resultant image of said subject by linking the respective sensitivity profiles of said coils, calculated from said reference dataset, with said resultant dataset.

A computer program product for operating a magnetic resonance imaging apparatus using partial parallel acquisition for projection reconstruction, wherein nuclear spins are excited in a subject and acquiring radiofrequency signals arising from the excited nuclear spins are acquired in a plurality of projection datasets, with a plurality of reception coils having respective sensitivity profiles under a readout gradient and wherein said projection datasets are entered into k-space, said computer program product being loadable into at least one computer of said magnetic resonance imaging apparatus for:

• under-scanning k-space with said coils and forming a complete projection datasets by progressively rotating said readout gradient through successive fixed step angles;
• producing a Cartesian resultant dataset by transforming said projection dataset in k-space onto grid points of a first Cartesian grid with a first grid constant;
• producing a Cartesian reference dataset by transforming a central region of the projection dataset in k-space onto a second Cartesian grid having a second grid constant that is smaller than said first grid constant;
• calculating the respective sensitivity profiles of said coils from said reference dataset;
• and
• reconstructing a resultant image of said subject by linking the respective sensitivity profiles of said coils, calculated from said reference dataset, with said resultant dataset.