Journal of Ultrasound in Medicine, Vol 13, Issue 10 735-741, Copyright © 1994 by American Institute of Ultrasound in Medicine
Oversaturation of color may obscure small intraluminal partial occlusions in color Doppler imaging
J. Machi, B. Sigel, A. B. Roberts and M. B. Kahn
Medical College of Pennsylvania, Department of Surgery, Philadelphia 19129.
Color Doppler imaging has been reported to have a low degree of accuracy in
diagnosing nonocclusive deep venous thrombosis. In this modality the color
saturation while diagnosing deep vein thrombosis depends on the blood flow
velocity and the sensitivity setting of the color image. To determine the
effect of color saturation on the detection of thrombi, an in vitro
experiment was performed using a closed-loop tube circulation system with a
simulated small intraluminal partial occlusion. Heparinized blood was
circulated at three different velocities (2, 5.5, and 9 cm/sec) and the
vessels were scanned longitudinally and transversely with color Doppler
imaging at three color sensitivity settings (low, medium, and high
sensitivity). In appropriate color sensitivity settings (i.e., the low,
medium, and high sensitivity for the velocity of 9,5.5 and 2 cm/sec,
respectively), the color was saturated adequately in the tube lumen so that
the partial occlusion was delineated as a color filling defect in the color
field. In undersaturated color conditions, the partial occlusion was
depicted owing to its echogenicity, but not as a color filling defect. In
over-saturated color conditions, such as the high color sensitivity at the
high velocity, the partial occlusion was obscured by the excessive amount
of color. The over saturation of color may be one of the reasons color
Doppler imaging fails to detect deep vein thrombosis, particularly small
intraluminal thrombi.
