Doppler Ultrasonography - Science topic
Ultrasonography applying the Doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. (Stedman, 25th ed)
Questions related to Doppler Ultrasonography
I hope you are doing well.
I am using a Vantage Verasonics Research Ultrasound System to do Ultrafast Compound Doppler Imaging. I acquire the beamformed IQData with compounding angles (na = 3) and ensemble size of (ne = 75) which are transmitted at the ultrafast frame rate (PRFmax = 9kHz) and (PRFflow = 3kHz). Can I used the Global SVD clutter filter to process the beamformed IQData instead of conventional high-pass butterworth filter.
Your kind responses will be highly appreciated.
I recently register a clinical trial in patients with liver cirrhosis. One of the study variables is hepatic vein velocity. There are three hepatic vein and determine hepatic vein velocity is possible to all three veins and in different regions (i.e. proximal to ivc or distal or in sinusoids)
Which hepatic vein velocity is more reliable in cirrhotic patient for determine of hepatic vein velocity? Which section of vein is beter for determine this value?
I am working on a thesis project and I would like to analyse a number of waveforms obtained via ultrasound doppler.
Essentially, I have jpeg. files of the doppler trace but currently unsure how to calculate the area under the curve to determine mean height velocity in an easy, automated way. I thought some sort of program that can pick up the colour differences? And then allow me to have a scale set for both the x and y axis.
I have looked into programs to draw the area manually however this may have significant error.
I have attached a file for reference (see trace at bottom of image).
In Doppler ultrasonography, be it umbilical artery ultrasound or transcranial Doppler the focus is always on the maximal blood flow velocity, i.e. on the envelope of the spectrogram (see attached Figure).
Why is this the case and what are the underlying assumptions? By this I mean, why are we not interested in e.g. the mean flow velocity? I feel the 'maximum' is quite hard to define since the transition region is quite blurry
One assumption, I guess, is that in the insonated vessels such as the middle cerebral artery blood flow is more or less laminar. But still, why the max. velocity?
Thanks a lot!
I would like to do renal doppler ultrasonography after abdominal insufflation with carbon dioxide but the hyperechoic gas inside the abdominal cavity makes this procedure impracticle. I would like to share the experience of anyone who has successfuly conducted intraoperative renal ultrasonography during laparascopy to overcome this problem.
Hey, I have 2 pairs of PZT crystals (Piezoelectric) fixed to a tube in which water flows. The Transit time, or time from input transmitter (>500 KHz) to output receiver is to be measured. The time Along the flow is smaller and time Against the flow is larger. This time difference gives Velocity.
1. When I give a Sine input to both the Tx, I am getting the same phased output at Rx, Without any delay, or sometimes a sudden unmeasurable change of phase.
2. This happens for a pulse also
(The tubes are of resin and steel and have thick walls)
I am trying to generate shear waves of significant amplitude and penetration depth using single element transducer rather than using phased array probe as proposed by the SSI and ARFI-shear wave techniques.
If there is any specific transducer, please suggest me or if there is a chance of using Therapeutic transducer ?