GE GA000100, Руководство по обслуживанию

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GE H
EALTHCARE
D
IRECTION
GA091568, R
EVISION
5 VIVID E9 S
ERVICE
M
ANUAL
Chapter 5 - Components and functions (theory) 5 - 15
5-3-9 VIVID E9’s Operating Modes
5-3-9-1 2D-Mode (B-Mode)
2D-mode or B-Mode is a two-dimensional image of the amplitude of the echo signal. It is used for
location and measurement of anatomical structures and for spatial orientation during operation of other
modes. In 2D-mode, a two-dimensional cross-section of a three-dimensional soft tissue structure such
as the heart is displayed in real time. Ultrasound echoes of different intensities are mapped to different
gray scale or color values in the display. The outline of the 2D cross-section is a sector, depending on
the particular transducer used. 2D-mode can be used in combination with any other mode.
5-3-9-2 Octave Imaging
In Octave Imaging, sometimes called “Tissue Harmonic Imaging”, acoustic aberrations due to tissue are
minimized by receiving and processing the second harmonic signal that is generated within the
insonified tissue. VIVID E9`s high performance Octave Imaging provides superb detail resolution and
penetration, outstanding contrast resolution, excellent acoustic clutter rejection and an easy to operate
user interface for switching into Octave Imaging mode. Coded Harmonics enhances near field
resolution for improved small parts imaging as well as far field penetration. It diminishes low frequency
amplitude noise and improves imaging technically difficult patients. It may be especially beneficial when
imaging isoechoic lesions in shallow-depth anatomy in the breast, liver and hard-to-visualize fetal
anatomy. Coded Harmonics may improve the 2D-Mode image quality without introducing a contrast
agent.
5-3-9-3 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.
5-3-9-4 Color Doppler Mode
Color Doppler is used to detect motion presented as a two-dimensional display. There are three
applications of this technique:
• Color Flow Mode - used to visualize blood flow velocity and direction
• Power Doppler (Angio) - used to visualize the spatial distribution of blood
• Tissue Velocity Imaging - used to visualize tissue motion direction and velocity
5-3-9-5 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). 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), 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 be 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.