Journal of Ultrasound in Medicine, Vol 15, Issue 10 715-720, Copyright © 1996 by American Institute of Ultrasound in Medicine
Measurement of volume flow with time domain and M-mode imaging: in vitro and in vivo validation studies
K. Harrington, C. Deane and S. Campbell
Department of Obstetrics and Gynaecology, Homerton Hospital, London, United Kingdom.
Color velocity imaging quantification is a commercially available technique
that estimates volume flow within vessels by combining velocity data,
acquired by time domain correlation, with vessel diameter measurements
obtained by M-mode imaging. By integrating the velocity profile over time,
quantitative volume flow calculations may be made. To investigate the
accuracy of this system, we used two flow phantoms over a range of steady
and pulsatile flows for in vitro evaluation, and the common carotid artery
of 10 women on five consecutive occasions was insonated for in vivo
assessment. In flow phantom studies, accuracy was within 8% for flows above
200 ml/min, but decreased at lower flows depending on the depth,
beam-vessel angle used, and steering of the beam. At angles greater than 70
degrees, velocity errors made quantitative measurement of flow unreliable,
whereas at angles less than 30 degrees, the increased error in calculating
vessel diameter led to large errors of area estimation, and hence made flow
measurements unreliable. For the in vivo studies on the carotid artery the
intraoperator repeatability values for the three operators were 9.92% (A),
13.74% (B), and 13.24% (C). The interoperator repeatability for the group
was 15.30%. This study suggests that the color velocity imaging
quantification technique is an accurate and reproducible method of
assessing volume flow in vessels. However, in our experience, obtaining
volume flow data is more time consuming and operator dependent than
traditional Doppler techniques. The color velocity imaging quantification
system may be of use in monitoring conditions in which changes in volume
flow in a vessel or to an organ is an important part of the disease
process.
