GE Voluson P8 BT16 Basic Service Manual page 215

GE DRAFT
DIRECTION 5723243, R
5-2-1-3 Color Doppler Modes
Color Doppler is used to detect motion presented as a two-dimensional display.
There are following applications of this technique:
• Color Flow Mode (C) - used to visualize blood flow velocity and direction
• Power Doppler (PD) - used to visualize the spatial distribution of blood
• Bi-Directional Angio (HD-Flow) - used to visualize flow direction with spatial resolution and low
artifact visibility
5-2-1-3-1 Color Flow Mode
A real-time two-dimensional cross-section image of blood flow is displayed. The 2D cross-section is
presented as a full color display, with various colors being used to represent blood flow (velocity,
variance, power and/or direction). Often, to provide spatial orientation, the full color blood flow cross-
section is overlaid on top of the grayscale cross-section of soft tissue structure (2D echo). For each pixel
in the overlay, the decision of whether to display color (Doppler), gray scale (echo) information or a
blended combination is based on the relative strength of return echoes from the soft tissue structures
and from the red blood cells. Blood velocity is the primary parameter used to determine the display
colors, but power and variance may also used. A high pass filter (wall filter) is used to remove the
signals from stationary or slowly moving structures. Tissue motion is discriminated from blood flow by
assuming that blood is moving faster than the surrounding tissue, although additional parameters may
also be used to enhance the discrimination. Color flow can be used in combination with 2D and Spectral
Doppler modes as well as with 3D mode.
5-2-1-3-2 Power Doppler
A real-time two dimensional cross-section of blood flow is displayed. The 2D cross-section is presented
as a full color display, with various colors being used to represent the power in blood flow echoes. Often,
to provide spatial orientation, the full color blood flow cross-section is overlaid on top of the gray scale
cross-section of soft tissue structure (2D echo). For each pixel in the overlay, the decision of whether
to display color (Doppler power), gray scale (echo) information or a blended combination is based on
the relative strength of return echoes from the soft-tissue structures and from the red blood cells. A high
pass filter (wall filter) is used to remove the signals from stationary or slowly moving structures.
Tissue motion is discriminated from blood flow by assuming that blood is moving faster than the
surrounding tissue, although additional parameters may also be used to enhance the discrimination.
The power in the remaining signal after wall filtering is then averaged over time (persistence) to present
a steady state image of blood flow distribution. Power Doppler can be used in combination with 2D and
Spectral Doppler modes as well as with 3D mode.
5-2-1-3-3 Bi-Directional Angio (HD-Flow Mode)
Directional Power Doppler is a Power Doppler mode incorporating the flow direction (much like Color
Doppler) into the displayed image. The focus of the settings for Directional Power Doppler is for high
spatial resolution and low artifact visibility, allowing vessels to be seen with less blooming and finer
detail.
6 DRAFT (M
EVISION
Chapter 5 - Components and Functions (Theory)
23, 2018)
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V ™ P8 / V
OLUSON OLUSON
B S M
ASIC ERVICE
™ P6
ANUAL
5-7