Optimizing Spectral Doppler
LOGIQ 7 Online Help 5-99
Direction 2392536-100 Rev. 1
PRF
Description Adjusts the velocity scale to accommodate faster/slower blood
flow velocities. Velocity scale determines pulse repetition
frequency.
If the sample volume gate range exceeds single gate PRF
capability, the system automatically switches to high PRF mode.
Multiple gates appear, and HPRF is indicated on the display.
High PRF High Pulse Repetition Frequency (HPRF) is a special operating
mode of PW Doppler. In HPRF mode, multiple energy pulses
are used. This allows higher velocities to be detected without
causing aliasing artifacts. HPRF mode is used when detected
velocities exceed the processing capabilities of the currently
selected PW Doppler scale or when the selected anatomical site
is too deep for the selected PW Doppler scale. The pulse
repetition frequency (PRF) is displayed to the left of the
spectrum in frames per second.
NOTE: Ensure that only one gate overlays a blood vessel at a time.
Otherwise, signals from more than one flow area are
superimposed.
Adjusting To raise/lower, adjust the PRF on the Touch Panel (PRF and
Wall Filter share the same control. Press the control to toggle
between PRF and Wall Filter). The display updates velocity
scale parameters after you adjust the velocity scale.
Values Velocity Scale values vary by probe and application. In Triplex,
when you change the velocity scale in Color Flow, the Doppler
Mode velocity scale is also updated.
Velocity Scale values are returned to the factory or user preset
value when you change the following: Probe, Exam Category,
Exam Calcs, or New Patient.
Benefits Blood flow information is not cut off due to the effect of aliasing.
Affect on other
controls
When you raise the velocity scale, the spectral waveform may
decrease in size; when you lower the velocity scale, the spectral
waveform may increase in size. Changes in the spectrum are
relative to changes in the velocity scale, that is, it sizes
accordingly. When you adjust the velocity scale, CINE memory
is cleared. Adjustments may affect sample volume size and
Doppler wall filter.
Bioeffects Changing the velocity range may change the TI and/or MI.
Observe the output display for possible effects.
To Next Page
Loading...
Need help?
General
