GE Voluson 730Pro, Basic User Manual

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PD Mode
9. PD Mode (Power-Doppler Mode)
Sonographic diagnostics can be greatly extended by Color-Doppler sonography. Still, Color-Doppler
sonography has deficits, especially in displaying very slow flow velocities - such as neovascularization
to be found in malignant tumors.
Power-Doppler intends to erase this deficit by displaying such slow flow velocities.
In gynecologic and obstetric applications the advantages can be clearly seen in the display of placental
blood circulation. With an eutrophic fetus the blood flow can be seen over the total extent of the
placenta. In the radiology field too, advantages for slow flows can be seen (e.g, kidney, liver, prostate,
etc.). This new technique is not intended to replace hitherto established sonographic techniques, but to
enhance them especially in the above mentioned fields.
Advantages compared to Color-Doppler:
-
less dependent on the incident angle
- no aliasing
- less dependent on the direction
- wherever slow flows occur
(e.g., blood circulation, veins, etc.)
Functional description:
In contrast to Color-Doppler, a basically different physical parameter of the reflected ultrasound beam
is used for color coding, so that the regularities of coloring, too, are different.
The ultrasound angiography analyzes the amplitude and Color-Doppler the frequency shift of the
reflection. The amplitude is determined by the amount with respect to the density of the blood cell
aggregates collected by the measuring volume of the ultrasound beam, and is thus independent from
the angle between blood flow direction and the incident ultrasound beam, while the frequency shift is
determined by the velocity of the reflectors.
Power-Doppler imaging generates a Color image by using the Doppler principles.
This Color image is overlaid onto the 2D image. The Power-Doppler image provides information
about the energy (Power) of the blood cell motion.
The amplitudes of the Color-Doppler signal are evaluated and displayed with special color coding.
All velocity-determined functions (Baseline, Scale, Display Mode, etc.) are not available in Power-
Doppler imaging.
Power-Doppler can be combined with spectral Doppler.
Power-Doppler is only possible with electronic transducers.
The PD mode is subdivided in two groups. In these groups you will see how to use PD mode and
how to adjust the PD settings.
To use the PD mode review: PD Main Menu (chapter 9.1)
To adjust PD setting review: PD Sub Menu (chapter 9.3)
To use special utilities review: Utilities (chapter 12) and Gray Chroma Map (chapter 12.1)
Voluson® 730Pro - Basic User Manual
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