Fig. 2

This describes the schematic for the application of CRUISE gating to Dual-phase 3D WH bSSFP with separate systolic and diastolic navigators. FH: Foot-head; ACQ_S: systolic acquisition; ACQ_D: diastolic acquisition Top panel: image navigator in systole. Bottom panel: image navigator in diastole. The oscillating line (blue line) represents the calculated image position compared to end-expiration (top line of graph). 600 cardiac cycles are used to generate the final gating threshold. In the first 300 cardiac cycles 3D WH bSSFP k-space was completely filled at any respiratory position. The temporary gating threshold is created by this initial data (green line), which represents the worst (most inspiratory) navigator position. During the second 300 cardiac cycles, the most motion corrupted 3D WH bSSFP k-space segment, as defined by the most inspiratory navigator position, was discarded and re-measured in the following cardiac cycle. If the FH position of the re-acquired segment was higher (closer to expiration) than the temporary inspiratory gating thresh-hold, it was kept, resulting in an updated gating thresh-hold. On the other hand, if the position of the re-acquired segment fell below the threshold it was ignored and re-acquired in the subsequent cardiac cycle. The temporary gating threshold improves until a final gating threshold is reached