Method and apparatus for acquiring free-breathing MR images using navigator echo with saturation RF pulse
AssigneeGeneral Electric Company
InventorsMaggie M. Fung, Thomas K. F. Foo
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Abstract
A system and method of free-breathing MR imaging saturates an entire navigator profile at the end of an imaging segment of physiological motion cycle, e.g., heart cycle, thereby providing a uniform recovery of longitudinal magnetization for the next imaging cycle. Through use of at least one dephaser gradient following the image acquisition segment and a navigator RF saturation pulse, residual transverse magnetization is dephased and spins within a navigator tracker are saturated to ensure a uniform recovery of longitudinal magnetization for the next imaging period.
Claims25
An magnetic resonance (MR) imaging apparatus comprising:
- a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images;
- and
- a computer programmed to apply a pulse sequence during an imaging period of a free-breathing gated acquisition, the pulse sequence defined by:
- a navigator RF excitation pulse designed to selectively excite a tracker column;
- an image acquisition segment designed to acquire MR data from a region-of-interest;
- and
- a navigator RF saturation pulse designed to saturate the tracker column such that longitudinal-magnetization recovery in the tracker column is uniform for a next imaging period.
A method of MR imaging comprising the steps of:
- (A) acquiring navigator echo data elicited by an RF navigator excitation pulse applied to a tracker portion of a subject to be imaged;
- (B) applying an imaging sequence to acquire MR data from a region-of-interest;
- (C) applying an RF saturation pulse to saturate spins within the tracker portion after acquisition of the MR data;
- (D) repeating steps (A)-(C) in each cycle of a physiologically gated acquisition;
- and
- (E) reconstructing an image based on the acquired MR data.
A computer readable storage medium having instructions stored thereon that when executed by a computer cause the computer to:
- acquire navigator tracking data from a navigator excitation region;
- acquire imaging data for a segment of k-space from a region-of-interest;
- suppress residual longitudinal magnetization in the navigator excitation region;
- repeat the acquisition of tracking data and imaging data and suppression of longitudinal magnetization every cycle of a gated acquisition until k-space is acquired;
- and
- reconstruct an image based on the imaging data.
Dependencies are inferred from the claim text.