Multi-dimensional cardiac and respiratory imaging with MRI
A 5-dimensional imaging method and system is provided to acquire and display the effect of dynamic physiologic changes (either spontaneous or induced) on cardiac function of a patient's heart to elucidate their effects on diastolic myocardial function. In a patient free-breathing magnetic resonance imaging study, 3-dimensional spatial information is encoded by a non-Cartesian 3-dimensional k-space readout trajectory and acquired concurrently with recordings of cardiac and respiratory cycles. The advantage of using non-Cartesian sampling in this invention compared to, for example, Cartesian sampling is higher scan acceleration, improved robustness to motion/flow effects (incoherent instead of coherent artifacts) and robustness to missing data points in k-space.
1. A 5-dimensional magnetic resonance (MR) imaging method of a patient's heart, comprising:
(a) in a patient free-breathing magnetic resonance imaging study of said patient's heart, a magnetic resonance imaging (MRI) computer system acquiring 3-dimensional volumetric spatial information of said patient's heart and concurrently recording cardiac and respiratory cycles of said patient, wherein said 3-dimensional volumetric spatial information is sampled with a non-Cartesian 3-dimensional k-space readout trajectory which is incorporated into a magnetic resonance imaging sequence, wherein said MRI computer system acquisition comprises a plurality of MRI acquisition segments of a plurality of readouts of said heart, whereby each segment is repeated multiple times in order to cover the at least a full period of a cardiac cycle and at least a full period of a respiratory cycle of said patient, wherein the MRI computer system combines the acquired 3-dimensional volumetric spatial information of the non-Cartesian 3-dimensional K-space readout trajectory in the MRI sequence with the plurality of readouts of the heart representing said at least full period of the cardiac cycle and said at least full period respiratory cycle, whereby the plurality of readouts of said heart for both the cardiac and respiratory cycles are defined as 2-dimensional non-spatial information in order to form a 5-dimensional data map of the patient's heart; and
(b) for each cardiac and respiratory temporal phase combination in said recorded cycles, said MRI computer system displaying at least one of the 3-dimensional volumetric spatial measurements of the atria and ventricles of said patient's heart, together with either the rate of change, minimum, maximum, or slope of these volume based measurements with respect to each of said cardiac and respiratory cycles, wherein the MRI system computer displays 3 of the 5 dimensions that are selected from the 5-dimensional data map, and wherein at least one non-spatial dimension is displayed as one of the 3 dimensions selected from the 5-dimensional data map that is displayed.
2. The method as set forth in claim 1 , wherein said non-Cartesian 3-dimensional k-space readout trajectory is selected as either: a non-Cartesian 3-dimensional cones k-space readout trajectory, a non-Cartesian 3-dimensional echo-planar imaging (EPI) k-space readout trajectory, a non-Cartesian 3D Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) k-space readout trajectory, a non-Cartesian 3D stack of spirals k-space readout trajectory, a non-Cartesian 3D stack of rings k-space readout trajectory, or a non-Cartesian 3-dimensional projection reconstruction (PR) k-space readout trajectory, or any other rapid 3D k-space readout trajectory.
3. The method as set forth in claim 1 , wherein said non-Cartesian 3-dimensional k-space readout trajectory traverses data points along arbitrary trajectories instead of the straight rectilinear line trajectories that are common in Cartesian sampling.
4. The method as set forth in claim 1 , wherein said non-Cartesian 3-dimensional k-space readout trajectory traverses data points occurring along intersecting diagonal line trajectories, spiraling trajectories, circular trajectories occurring within a 3D k-space, or a combination thereof.
5. The method as set forth in claim 1 , complementing the acquisition of said 3-dimensional volumetric spatial information with MRI acceleration techniques of parallel imaging, spatiotemporal undersampling and reconstruction, compressed sensing or a combination thereof.
6. The method as set forth in claim 1 , wherein said magnetic resonance imaging sequence utilizes principles of free-induction decay, steady-state free precession, gradient echo, spin echo, magnetization preparation modules, or a combination thereof in order to prepare image contrast from the magnetically resonant spins.
7. The method as set forth in claim 1 , wherein the respiratory and cardiac cycles are recorded by using at least one of: an electrocardiogram (ECG), pulse-ox plethysmograph, respiratory bellows, MRI navigators, MRI self-navigation signals, auxiliary ultrasound information, auxiliary optical sensors, or a combination thereof.
8. The method as set forth in claim 1 , complementing said 3-dimensional volumetric spatial information, respiratory information, and cardiac information with additional flow information, perfusion information or a combination thereof.
9. The method as set forth in claim 1 , complementing said 3-dimensional volumetric spatial information and respiratory and cardiac information with MRI T1-relaxation information, MRI T2-relaxation information, or a combination thereof.
10. The method as set forth in claim 1 , complementing said 3-dimensional volumetric spatial information and respiratory and cardiac information with oxygenation level information, the distribution of an administered contrast agent or a combination thereof.
11. The method as set forth in claim 1 , complementing said 3-dimensional volumetric spatial information and respiratory and cardiac information with diffusion information.
12. The method as set forth in claim 1 , complementing said 3-dimensional volumetric spatial information and respiratory and cardiac information with MR resonant frequency information.
13. The method as set forth in claim 1 , said patient free-breathing magnetic resonance imaging study further comprising internally or externally inducing respiratory pressure variations to said patient with a respiratory bellows.