Color Flow Overview; Acoustic Streaming With Cysts - Siemens Acuson S1000 Instructions For Use Manual

Color Flow Overview

During Color imaging, the system applies color to indicate velocities of blood flow in a defined
region of interest (ROI) within a 2D image. Color is supported by all imaging transducers.
Color Doppler Velocity (CDV) applies color to the velocities and directions of blood flow

within the ROI.
Color Doppler Energy (CDE), or Power mode, applies color to the energy measurement

generated by the blood flow within the ROI.

Acoustic Streaming with Cysts

WARNING: Acoustic streaming may occur in fluid filled cysts under certain conditions, for
example, when it is necessary to repetitively image a fluid filled cyst with long ultrasound pulses.
To verify that flow inside of a cyst is actually acoustic streaming, use spectral Doppler with a
large gate and low scale and filter settings and move the sample volume around the inside of the
cyst.
Acoustic streaming is a well-known physical phenomenon that can occur while imaging fluid
filled cysts. Under typical imaging conditions, the color flow and Doppler scale and filter settings
are set too high to see the low velocity acoustic streaming, however, physical artifacts may be
generated under the following conditions:
Long ultrasound pulses are repetitively used to image a fluid filled cyst about 1 centimeter

or larger.
The fluid in the cyst has low viscosity.

The center of the cyst is located near the elevation focus of the transducer.

The PRF setting is low. (Acoustic streaming flow is typically visible between 1 to 2

centimeters per second.)
The wall filter setting is low. (Acoustic streaming velocities are usually set by filters.)

You can confirm the flow inside of a cyst is acoustic streaming by using a large gate and low
scale and filter settings and then moving the sample volume inside the cyst.
Note: Flow away from the transducer is visible at multiple locations throughout the center of the cyst
if it is acoustic streaming. It is more difficult to generate acoustic streaming near the edge of the cyst.
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