What is persistence in ultrasound?
Table of Contents
What is persistence in ultrasound?
Persistence defines how much of the previous image is taken over into the current frame. This makes the resulting live image appear smoother and less wobbly. This can be useful to a certain extent, especially when working with the US machine for a long time.
What is dynamic range ultrasound?
Abstract. In medical ultrasound imaging, dynamic range (DR) is defined as the difference between the maximum and minimum values of the displayed signal to display and it is one of the most essential parameters that determine its image quality.
How do you optimize an ultrasound image?
- Principles of image optimization in echocardiography. In order to obtain optimal ultrasound images, it is necessary to adjust several parameters continuously during the examination.
- Adjusting image depth and zoom.
- Gain: signal amplification.
- Frequency of ultrasound waves.
- Image focus.
- Frame rate.
What is BB mode in ultrasound?
Brightness mode (B mode) is the basic mode that is usually used. Ultrasound waves are emitted from piezoelectric crystals of the ultrasound transducer. Depending on the acoustic impedance of different materials, which depends on their density, different grades of white and black images are produced.
What is attenuation in ultrasound?
The amplitude and intensity of ultrasound waves decrease as they travel through tissue, a phenomenon known as attenuation. Given a fixed propagation distance, attenuation affects high frequency ultrasound waves to a greater degree than lower frequency waves.
What is reverberation in ultrasound?
REVERBERATION. Reverberation artifacts appear as a series of equally spaced lines. They are produced by an ultrasound beam repeatedly bouncing back and forth between two highly reflective interfaces or between the transducer and a strong reflector.
When is dynamic range used in sonography?
Dynamic Range (Compression) Dynamic Range (also known as Compression) allows you to tell the ultrasound machine how you want the echo intensity displayed as shades of gray. A broad/wide range will display more shades of gray and an overall smoother image.
Which factor will smooth grainy images in ultrasound?
Increasing the DR yields a higher number of gray scale levels (increased spatial resolution by increased contrast levels) and increased image detail and smoother images. Decreasing the dynamic range increases the contrast of the image, with more black and white areas than shades of gray.
What does harmonics do in ultrasound?
Harmonic imaging exploits non-linear propagation of ultrasound through the body tissues. The high pressure portion of the wave travels faster than the low pressure portion resulting in distortion of the shape of the wave.
What is PW mode in ultrasound?
Pulsed wave (PW) Doppler uses the Doppler principle that moving objects change the characteristic of sound waves. By sending short and quick pulses of sound, it becomes possible to accurately measure the velocity of blood in a precise location and in real time.
What causes ultrasound attenuation?
Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries.
What’s the difference between absorption and attenuation?
In Physics, the main difference between attenuation and absorption is that attenuation is the gradual reduction in the intensity of a signal or a beam of waves which is propagating through a material medium whereas the absorption is the way in which the energy of a photon is taken up by matter.
What is anisotropy ultrasound?
Anisotropy in ultrasound examination is an angle-generated artifact. It is produced in tissue that contains multiple, parallel linear sound interfaces (e.g., tendons, ligaments) that lead to the preferential reflection of the beam in one direction.
What causes shadowing on ultrasound?
Clean and dirty shadowing are common phenomena in ultrasound (US) imaging. Clean shadowing is thought to be produced by sound-absorbing materials (ie, stones), and dirty shadowing is thought to be produced by sound-reflecting materials (ie, abdominal gas), but these properties are not consistent.
Why is framerate important in ultrasound?
High frame rates enable us to see rapidly moving structures (such as heart valves) without motion artifacts, and also perform velocity and deformation analysis (i.e. tissue Doppler).
What does harmonic imaging improve?
Harmonics are most prominent in the central section of the transmitted beam. Hence lateral resolution is improved in harmonic mode. Reduced Image artefacts like reverberations, side and grating lobes. Improved contrast resolution as less “noise” and clutter (better signal to noise ratio).
What is the advantage of harmonic imaging?
Potential advantages of harmonic imaging include improved axial resolution due to higher frequencies and better lateral resolution due to narrower beams. Decreased noise from side lobes improves signal-to-noise ratios and reduces artifacts. Deleterious effects of the body wall are also reduced.
