Doppler ultrasound provides important information about blood flow that cannot be determined through standard gray-scale ultrasound alone. It allows observation of flow velocity and direction, aiding in diagnosis of various vascular diseases. Doppler works by detecting the frequency shift of sound waves reflected from moving objects like blood cells. There are two main types - Pulsed Wave Doppler which measures flow at a selected sample volume, and Continuous Wave Doppler which evaluates flow over a range of depths. Doppler ultrasound offers advantages over standard gray-scale such as assessing blockages, plaque, abnormal veins, and fetal well-being during pregnancy without known health risks.
2. Ultrasound Then & Now
• Since the ultrasound was first introduced, there are rapid
technological advances in electronics and piezoelectric
materials provided further improvements from to grey scale
images and from still images to real-time moving images.
• The advent of the microchip in the seventies and subsequent
exponential increases in processing power have allowed faster
and more powerful systems incorporating digital
beamforming, more enhancement of the signal and new ways
of interpreting and displaying data , such as power Doppler
and 3d imaging.
• It was not the end. Technology for ultrasound is growing day
by day with lots of new features to improve image quality and
diagnostic capabilities.
3. • Although ultrasound machines can show you the vessels even
in gray-scale without using color (specially arteries due to
pulstality). But it’s not enough to see the pulstality in 2D but it’s
essential to gather the information about flow and velocity of
the flow in vessels.
• In order to know this we have adapted the Doppler technologies
which gives us ability to check/know color flow and the
velocity of blood moving in vessels.
• It’s not about information of blood flow but it helps us to
diagnose various kind of diseases which developed due to
inaccurate velocities in vessels; i.e. Malformation, thickness of
Arteries, blockage in veins (deep Vein Thrombosis-DVT), etc.
4. What is Doppler & how It Works
• Doppler Theory stated that any directional motion between a light
source and an observer would produce a detectable frequency shift or
color change. Doppler’s theory is applicable to both light and sound.
• The Doppler effect is the change in frequency or wavelength of
a wave for an observer moving relative to its source.
• The sound frequency from an approaching source is higher than from
one receding.
5. • The smaller the angle between the insonated vessel and the probe, the higher is the
Doppler shift.
• There are two mainly 2 types of doppler we are using; PW(Pulsed Wave Doppler) &
CW(Continuous Wave Doppler).
**Pls explain the difference b/w PW & CW if required.
6. Advantages of Color Doppler Over Gray-scale
• A Doppler ultrasound test uses reflected sound waves to see how
blood flows through a blood vessel.
• It helps doctors assess the blood flow through major arteries and
veins, for many applications i.e; Abdomen, Vascular, Small Parts,
Obstetrics & Gyn, etc.
• It can show blocked or reduced flow of blood through narrow areas
in the major arteries of the neck & Legs.
• Check for varicose veins or other vein problems.
• Find the presence, amount, and location of arterial plaque. Plaque in
the carotid arteries can reduce blood flow to the brain. This may
increase the risk of stroke.
7. • Find the presence, amount, and location of arterial plaque. Plaque in
the carotid arteries can reduce blood flow to the brain. This may
increase the risk of stroke.
• Guide treatment such as laser or radiofrequency ablation of abnormal
veins.
• During pregnancy, Doppler ultrasound may be used to look at blood
flow in an unborn baby to check the baby's health.
• It may check blood flow in the umbilical cord, through the placenta, or
in the heart and brain of the fetus. This test can show if the fetus is
getting enough oxygen and nutrients.
• There are no known risks linked with a Doppler ultrasound test. This
test will not harm an unborn baby in pregnancy ultrasound.