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. 2020 Nov 12;2(6):e200219. doi: 10.1148/ryct.2020200219

Figure 1:

Five-dimensional flow MRI framework. A, Pulse sequence: continuous acquisition with spatial encoding following a three-dimensional (3D) radial, spiral phyllotaxis sampling pattern, interspersed with superior-inferior (SI) projections, which were used to extract, B, cardiac and respiratory self-gating signals. Bipolar flow–encoding gradients were added to spatial-encoding gradients in patterns of four successive repetition times (TR) required for 3D velocity-encoding. The total number of TRs per interleaf has been reduced in this figure for demonstration purposes (see Methods). C, Data are retrospectively binned into cardiac, respiratory, and velocity-encoded dimensions and gridded onto Cartesian coordinates for reconstruction using a compressed-sensing framework with a data-fidelity term and cardiac and respiratory regularization. The electrocardiogram (ECG) is shown for demonstration purposes only. TR representations are lengthened relative to the ECG. Gx, Gy, and Gz represent the magnetic gradients in the x, y, and z directions, respectively. RF = radiofrequency pulse.

Five-dimensional flow MRI framework. A, Pulse sequence: continuous acquisition with spatial encoding following a three-dimensional (3D) radial, spiral phyllotaxis sampling pattern, interspersed with superior-inferior (SI) projections, which were used to extract, B, cardiac and respiratory self-gating signals. Bipolar flow–encoding gradients were added to spatial-encoding gradients in patterns of four successive repetition times (TR) required for 3D velocity-encoding. The total number of TRs per interleaf has been reduced in this figure for demonstration purposes (see Methods). C, Data are retrospectively binned into cardiac, respiratory, and velocity-encoded dimensions and gridded onto Cartesian coordinates for reconstruction using a compressed-sensing framework with a data-fidelity term and cardiac and respiratory regularization. The electrocardiogram (ECG) is shown for demonstration purposes only. TR representations are lengthened relative to the ECG. Gx, Gy, and Gz represent the magnetic gradients in the x, y, and z directions, respectively. RF = radiofrequency pulse.