Free-breathing MRI with motion compensation
A method for acquiring magnetic resonance imaging data with respiratory motion compensation using one or more motion signals includes acquiring a plurality of gradient-delay-corrected radial readout views of a subject using a free-breathing multi-echo pulse sequence, and sampling a plurality of data points of the gradient-delay-corrected radial readout views to yield a self-gating signal. The self-gating signal is used to determine a plurality of respiratory motion states corresponding to the plurality of gradient-delay-corrected radial readout views. The respiratory motion states are used to correct respiratory motion bias in the gradient-delay-corrected radial readout views, thereby yielding gradient-delay-corrected and motion-compensated multi-echo data. One or more images are reconstructed using the gradient-delay-corrected and motion-compensated multi-echo data.
1. A method for acquiring magnetic resonance imaging data with respiratory motion compensation using one or more signals, the method comprising:
generating, using an MRI scanner, a free-breathing multi-echo pulse sequence comprising:
a gradient delay calibration acquisition module configured to (i) acquire calibration data from positive and negative gradient calibrations in both the x and y directions along a k-space trajectory and (ii) cross-correlate the calibration data to calculate k-space sample shifts in k x and k y directions, respectively; and
an imaging acquisition module configured to (i) acquire radial readout views for all k z increments before rotating to a subsequent azimuthal angle and (ii) correct the k-space trajectory for the radial readout views along each azimuthal angle using the k-space sample shifts;
generating a self-gating signal based on the radial readout views;
using the self-gating signal to correct respiratory motion bias in the radial readout views, thereby yielding gradient-delay-corrected and motion-compensated multi-echo data; and
reconstructing one or more images using the gradient-delay-corrected and motion-compensated multi-echo data.
2. The method of claim 1 , further comprising:
measuring one or more biomarker values using the images; and
displaying the biomarker values in a graphical user interface (GUI).
3. The method of claim 2 , wherein the biomarker values comprise a Proton-Density Fat Fraction (PDFF) value and an effective transverse relaxation rate (R* 2 ) value.
4. The method of claim 2 , wherein the biomarker values comprise a mapping of T 1 relaxation time, T2 relaxation time, and tissue stiffness.
5. The method of claim 2 , further comprising:
applying a background mask to the images to exclude a background air region from the measurement of the biomarker values.
6. The method of claim 1 , wherein the radial readout views are acquired using a golden-angle ordering scheme.
7. The method of claim 1 , wherein the self-gating signal is generated by sampling data points of the radial readout views corresponding to a first echo at a k-space origin.
8. The method of claim 1 , wherein the self-gating signal is generated by sampling data points of the radial readout views corresponding to each individual echo at a k-space origin.