In vivo validation of the time domain velocity measurement technique of blood flow in human fetuses.

Time domain ultrasonography is an alternative to Doppler analysis of blood flow direction and velocity. The time domain technique uses timing information between successive echo pulses to measure flow velocities directly through a color display map. This study was undertaken to validate this technique for measuring peak systolic velocity compared to the pulsed-wave Doppler method in human fetuses. Twenty normally developing fetuses were included in the study. The fetal abdominal aorta and the umbilical artery were studied in 12 and eight cases, respectively. We first estimated flow velocity using time domain ultrasonography and immediately after pulsed Doppler was used. The intraclass correlation coefficient was used to assess the agreement between measurements. A close correlation was found (intraclass correlation coefficient = 0.96). Our results show that time domain ultrasonography seems to be a valid technique for imaging fetal vessels and for measuring blood flow velocity.