Preliminary experiences using quantitative color velocity imaging (CVI): a simple means to measure fetal volume flow?

Abstract

Purpose: Color velocity imaging (CVI) quantifies blood flow using time domain ultrasonography and M‐mode vessel diameter measurements. It has been validated in vitro and correlates well with Doppler based velocity measurements. The purpose of this study was to apply an easy to use CVI software algorithm in fetal studies.Methods: A high resolution ultrasound system (ATL HDI 5000, 7–4 and 5–2 MHz curved probes) was used. Analysis of ultrasound data was performed using dedicated software (HDILab, version 1.91; CVI_Q plug‐in version 2.0). The content of the cineloop, usually with several cardiac cycles, is stored in digital format, concurrent with an ongoing exam. Volume flow, peak velocity and vessel diameter (derived from color M‐mode) were measured off‐line.Results: Data acquisition is quick and simple. The proximal portion of the intrahepatic umbilical vein with its straight course offers good sampling conditions. The ductus venosus can also readily be measured. Off‐line analysis does not require specific hardware and takes less than 3 min per vessels. There is significant intraobserver variablity, but generally CVI volumes flow measurements agreed with published data derived from invasive or Doppler based methods.Conclusions: CVI volume flow measurement using this system is rapid and easy. The software also delineates the functional lumen diameter (based on color flow information) and calculates blood flow velocities, enabling correlation with Doppler measurements. The calculations are based on the assumption of certain standard conditions (laminar flow and circular cross section, e.g. in adult carotid artery), but restrictions in fetal vessels (e.g. tortuous vessels of the free umbilical cord with regions of non‐laminar flow, fetal and maternal movements) apply.