Fig. 1.

Diagram summarizes segmented K-space gradient-recalled echo acquisition in a multiphase, single-slice mode. Each R-R interval is divided into multiple cardiac phases (cine frames). Cine frame has relatively short duration, so that only portion, or segment, of K-space can be acquired. Multiple RF pulses can be applied during this segment, each corresponding to line of K-space. Number of views per segment (NVS) is number of RF pulses that are applied during each segment, shown as NVS = 8 in this diagram. For TR of 10 msec, duration of each cine frame is 10 msec × 8 = 80 msec; hence, multiple cine frames can be acquired during typical R-R interval (which lasts approximately 1000 msec). Two segments are shown here, one obtained during systole and one obtained during diastole. Note that segments of K-space are usually not contiguous (like contiguous segments shown here) but are interleaved to minimize image artifacts. To complete 128 phase-encoding steps requires 128/8 = 16 R-R intervals.