Reverse Loop Order

Reverse Loop Order is used during gating with 3D Fast GRE to shorten scan times by switching loop order of slice- and phase-encoding steps.

• Enter 0 (off) for the system to scan all lines of k-space along the slice encoding direction first and then it is looped along phase encoding direction. Therefore: Scan time = Number of heartbeats = Number of phase encoding lines to be collected. For example, if you have a phase matrix of 128 selected with a Phase FOV of 1, your scan time takes 128 heartbeats to complete.
• Enter 1 (on) for the system to collect all lines of k-space along the phase encoding direction first and then it is looped along the slice encoding direction. Therefore: Scan time = Number of heartbeats = Number of slab locations selected. For example, if you have selected a slab of 44 locations, your scan time takes 44 heartbeats to complete.