GE Voluson E8 Service Manual page 191

GE H DRAFT
EALTHCARE
D KTD102576, R
IRECTION
5-2-1-2 M-Mode
In M-mode, soft tissue structure is presented as scrolling display, with depth on the Y-axis and time on
the X-axis. It is used primarily for cardiac measurements such as value timing on septal wall thickness
when accurate timing information is required. M-mode is also known as T-M mode or time-motion mode.
Ultrasound echoes of different intensities are mapped to different gray scale values in the display.
M-mode displays time motion information of the ultrasound data derived from a stationary beam.
Depth is arranged along the vertical axis with time along the horizontal axis. M-mode is normally used
in conjunction with a 2D image for spatial reference. The 2D image has a graphical line (M-line)
superimposed on the 2D image indicating where the M-mode beam is located.
5-2-1-2-1 MCFM Mode (M Mode + Color Flow Mode)
Color Flow Mode and Color M Mode are Doppler modes intended to add color-coded qualitative
information concerning the relative velocity and direction of fluid motion within the 2D mode or M
mode image. Color Flow overlays color on the M mode trace using velocity and variance color
maps. The Color Flow wedge overlays the 2D mode image and M mode timeline.
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
• Tissue Doppler (TD) - used to visualize tissue motion direction and velocity
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.
7 DRAFT (A
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Chapter 5 - Components and Functions (Theory)
23, 2012)
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