Frequency response of multi-phase segmented k-space phase-contrast

A theoretical analysis of the temporal frequency response of multi‐phase segmented k‐space phase‐contrast was developed. This includes the effects of both segment duration and the number of cardiac phases that are reconstructed. An increase in the number of views per segment and the corresponding increase in segment duration results in an increased smoothing or low‐pass filtering of the time‐resolved flow waveform. Reconstruction of all intermediate cardiac phases makes the Nyquist sampling frequency independent of the number of views per segment. This analysis was verified experimentally using a multi‐phase phase‐contrast segmented k‐space MR pulse sequence. This sequence reconstructs all intermediate cardiac phases and uses fractional segments at the end of the cardiac cycle if an entire segment does not fit. The use of fractional segments increases the portion of the cardiac cycle over which data are acquired.