3B Scientific UE9020400 Doppler Sonography Owner’s Manual
- June 1, 2024
- 3B Scientific
Table of Contents
3B Scientific UE9020400 Doppler Sonography
EXPERIMENT PROCEDURE
- Doppler sonographic examinations of a human model arm.
- Measurement of the flow velocity of the blood.
- Diagnosis of stenosis (vascular stricture) in an arm.
- Recording of Doppler spectra and pulse curves.
OBJECTIVE
Investigating a model arm
SUMMARY
The goal of the experiment is to learn how blood flow measurements are made
with Doppler ultrasound. A realistic arm model is used to show the differences
between continuous (venous) and pulsatile (arterial) flow and between normal
blood flow and stenosis.
REQUIRED APPARATUS
BASIC PRINCIPLE
Doppler sonography uses the Doppler Effect to assess whether structures
(usually blood) are moving towards or away from the ultrasonic probe, and its
relative velocity. By calculating the frequency shift of a particular sample
volume, for example, a jet of blood flow over a heart valve, the speed and
direction of this sample volume can be determined and visualized. Doppler
frequency shift is the difference in ultrasonic frequency between transmitted
and received echoes, i.e. the echo frequency minus the transmitter
frequency. The Doppler frequency is proportional to the blood flow velocity.
Doppler sonography is particularly useful in cardiovascular studies (sonography of the vasculature system and heart) and essential in many areas such as determining reverse blood flow in the liver vas-culture in portal hypertension. The Doppler information is displayed graphically using spectral Doppler or as an image using colour Doppler.
For the experiment, a pump is switched on and the speed is adjusted in a middle range (approx. 4000 min-‘). The mode is GK (continuously, venous). With the Doppler probe and coupling gel, the arm model is scanned for a vessel with a significant audio signal. The flow in the spectral image is analyzed for negative and positive components. The probe direction is then switched by 180°. Then the the vessel is scanned for changes in the spectral image (stenosis) and the differences between the images of the “healthy” vessel and the stenosis will be characterized. Lastly, the pump is switched to P, and P, mode (pulsatile) the images are analyzed and the pulse rate is determined.
EVALUATION
Figure 1 shows a continuous (venous) flow with a mean Doppler shift of approx. -700Hz. The minus in the Doppler shift means a flow away from the probe.
Figure 2 is the spectral distribution with the rotated probe. Flow towards the
probe (the same Doppler shift, but positive).
Figure 3 is the Doppler spectral figure of a stenosis. The differences to a
normal (healthy) figure shown in Figure 1 are:
- A local increase of the maximum Doppler shift (maximum flow velocity).
- A decrease in mean frequency and a broadening of the spectra.
- An increase of reflux phenomenon (negative and positive parts of the spectra). Figure 4 shows the pulsatile flow of P, with a pulse rate of ca. 90min-1.