Shared excitation phase encode grouping for improved throughput cardiac gated MRI cine imaging

A cine magnetic resonance imaging method in which k-space is segmented into n segments including a central segment having lowest frequency phase encoded views and a plurality of segments having progressively higher frequency phase encoded views, the method comprising:

• (a) monitoring cardiac cycles of a subject in a magnetic resonance imaging region;
• (b) in coordination with each of a plurality of monitored cardiac cycles, generating a series of magnetic resonance echo sequences each sequence generating a magnetic resonance echo with a phase encoding in one of the n segments, and such that each magnetic resonance echo phase encoded with a phase encoding in the lowest frequency segment has magnetic resonance echoes which are phase encoded with a phase encoding from a higher frequency segment of k-space temporal on either side thereof, and such that magnetic resonance echoes phase encoded with a phase encoding from the lowest frequency segment are generated at regular intervals with magnetic resonance echo phase encodings from higher frequency segments therebetween;
• (c) receiving magnetic resonance echo signals corresponding to each of the echoes;
• (d) sorting the magnetic resonance echo signals into groups, each group including a magnetic resonance echo signal phase encoded with a phase encoding from the lowest frequency segment and at least two contiguous magnetic resonance echo signals phase encoded with phase encodings from the higher frequency segments, at least one of the magnetic resonance signals from magnetic resonance echoes between temporal adjacent echoes phase encoded with a phase encoding in the lowest frequency segment being sorted into two groups;
• (e) repeating steps (b), (c), and (d) with each of the groups at substantially the same time in each of a plurality of monitored cardiac cycles;
• (f) reconstructing a magnetic resonance image from each group.

A cine magnetic resonance imaging apparatus comprising:

• means for monitoring cardiac cycles of a subject in a magnetic resonance imaging region;
• means for generating a series of magnetic resonance echoes in coordination with each monitoring cardiac cycle, the magnetic resonance echoes being phase encoded cyclically with low frequency phase encodings and high frequency phase encodings;
• means for receiving the magnetic resonance echoes and generating corresponding magnetic resonance signals, the magnetic resonance signals being phase encoded with the corresponding high and low frequency phase encodings;
• a plurality of data memory means each for storing a set of data that is reconstructible into a frame image representation, each frame image representation corresponding to a selected temporal point in the cardiac cycle;
• means for sorting the magnetic resonance signals such that each of the low frequency phase encoded magnetic resonance signals is stored in a corresponding one of the data memory means and each of the high frequency phase encoded magnetic resonance signals is stored in two data memory means which correspond to the two most temporally contiguous frame image representations;
• means for reconstructing a frame image representation from the magnetic resonance signals stored in each of the data memory means, whereby a plurality of temporally displaced frame image representations is generated for each cardiac cycle in which low frequency phase encoded magnetic resonance signals are unique to one of the frame image representations and high frequency phase encoded magnetic resonance signals are shared by temporally contiguous image representations.

A cine magnetic resonance imaging apparatus in which k-space is segmented into n segments including a central segment having lowest frequency phase encoded views and a plurality of segments having progressively high frequency phase encoded views, the apparatus comprising:

• means for monitoring cardiac cycles of a subject in a magnetic resonance imaging region;
• means for generating a series of magnetic resonance sequences in coordination with each of a plurality of the monitored cardiac cycles, each sequence generating a magnetic resonance echo with a phase encoding in one of a plurality of regions of k-space, the magnetic resonance echoes with a phase encoding in the lowest frequency region of k-space being generated at regular, spaced temporal intervals, the magnetic resonance echoes with phase encodings in higher frequency regions of k-space being generated between the echoes in the lowest frequency region of k-space;
• receiving means for generating magnetic resonance echo signals corresponding to each of the echoes;
• means for reconstructing into frame image representation magnetic resonance signals corresponding to the echoes phase encoded with phase encodings from the lowest frequency region of k-space and the magnetic resonance signals corresponding to echoes phase encoded with phase encodings from higher frequency regions of k-space wherein said higher frequency regions echoes are temporally between two next most contiguous echoes from the lowest frequency regions of k-space.