TIME-DOMAIN ULTRASONOGRAPHY DURING PREGNANCY

Time-domain ultrasonography is an alternative to Doppler analysis of b lood flow direction and velocity. The technique uses timing informatio n between successive echo pulses to measure flow velocities directly t hrough a color display map. Volume flow quantification also can be ach ieved by combining time-domain methods with M-mode ultrasonography. Th is report describes our preliminary experiences with fetal vascular im aging by time-domain ultrasonography, compares Doppler peak velocity c orrelation to time-domain sonography, and examines the in vitro accura cy of time-domain sonography combined with M-mode volume flow measurem ents. Excellent agreement was found between peak Doppler velocity meas urements and time-domain ultrasonography for a variety of maternal and fetal vessels (N = 29). Close volume-flow correlation was observed be tween a flow pump and time-domain ultrasonography under constant and p ulsatile conditions. Time-domain ultrasonography appears to be a usefu l alternative to Doppler techniques for imaging small fetal vessels an d also may provide the basis for accurate volume flow measurements dur ing pregnancy.