Doppler artifact

what is the most common artifact we see

aliasing

what is aliasing caused by

sampling too low

When evaluating arteries do you want high or low PRF

high PRF setting

what should you do first when there is aliasing

change your PRF settings, THEN baseline

What is range ambiguity

The second transmitted pulse is transmitted before all the echoes form the first are received

what is range ambiguity common in

superficial and cardiac imaging

what modalities exhibit range ambiguity

ALL pulse wave modalities

why was HPRF created

to intentionally manipulate the artifact

what is mirror image artifact

when a structure is located near a strong reflector

what can cause mirror image in doppler

the reflective vessel wall

how do you know what is real with mirror image artifact

use pulse wave

why can angle cause mirror image

because angles closer to 90 degrees dont allow us to see direction of flow

what causes harmonic double spectral envelope

non linear sound wave propagation which is overstimulation of flow

what causes spectral broadening

overstimulation of the PSV which diminishes the spectral window

what does laminar blood flow tell us

that blood is flowing in layers

what does a filler in spectral window tell us

turbulence, torturous vessels, etc

how can you fix broadening

angle

what is blossoming

occurs when the signal is over gained

what is color bleeding

when the color gain setting is too high and color bleeds out of vessel

How do we fix wall filter saturation

chagne angle and turn down wall filter

how could we fix flash artifact

increase the PRF and turn down color gain

why does spectral drop out occur

angle, high wall falter, sensitivity

how can you tell what true flow reversal is

the black lines

if color wall filter is set too high what happens

it removes low velocity flow that we may need to see

If color wall filter is set too low what happens

tissue movement gets color coded

If we are getting color dropout how do we fix that

turn up the PRF

if we have a small FOV what happens to the frame rate

it increases