FREQUENCY-RESPONSE OF MULTIPHASE SEGMENTED K-SPACE PHASE-CONTRAST

A theoretical analysis of the temporal frequency response of multi-pha se segmented k-space phase-contrast was developed. This includes the e ffects 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. R econstruction of all intermediate cardiac phases makes the Nyquist sam pling frequency independent of the number of views per segment. This a nalysis was verified experimentally using a multi-phase phase-contrast segmented k-space MR pulse sequence. This sequence reconstructs all i ntermediate cardiac phases and uses fractional segments at the end of the cardiac cycle if an entire segment does not fit. The use of fracti onal segments increases the portion of the cardiac cycle over which da ta are acquired.