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Ultrasound Artifacts

  • Intro
 
 
 
 
 
  
Magnetic Resonance Imaging Artifacts Open this link in a new window
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Artifact 

An image artifact is any image attribute, which is not present in the original imaged object. An image artifact is sometime the result of an improper operation of the imager, and in other times a consequence of natural processes or properties of the human body.
Artifacts in diagnostic ultrasound are a reflection or an echo, which appears on the display and represents the real anatomical structure not correctly. An artifact can be a false, multiple or misleading information introduced by the imaging system or by interaction of ultrasound with the adjacent tissue.

Artifacts in ultrasound can be classified as to their source like e.g.:
point physiologic (motion, different sound velocities, acoustical impedances of tissue);
point hardware (dimension of the ultrasound beam and the transducer array);
point imaging technique (B-mode, spectral Doppler, color Doppler, 3D ultrasound).
Image artifacts can occur in each medical ultrasound. Then an interpretation of the image is complicated and can eliminate the structural information of objects looking for.
See also Ultrasound Imaging Procedures.

• View the DATABASE results for 'Artifact' (60).Open this link in a new window.

 Further Reading:
  Basics:
Types of ultrasound artifacts?Open this link in a new window
   by www.frca.co.uk    
  News & More:
Ultrasonographic fata morganaOpen this link in a new window
2003   by ndt.oxfordjournals.org    
Noise 

An undesirable background interference or disturbance that affects image quality.
The noise is commonly characterized by the standard deviation of signal intensity in the image of a uniform object (phantom) in the absence of artifacts. The measured noise may depend on the particular phantom used due to variable effects. Noisy images appear when the signal to noise ratio is too low. There are various noise sources in any electronic system, including Johnson noise, shot noise, thermal noise.
See also Interference Artifact.

• View the DATABASE results for 'Noise' (15).Open this link in a new window.

Image Quality 

The perfect image quality is dependent on some assumptions of the propagation of ultrasound waves in tissues after generating in an imaging system. These assumptions are important for the developing of optimal ultrasound imaging systems.
point The sound velocity in the examined tissue is homogeneous and constant (around 1540 m/s).
point The propagation of ultrasound is straight ahead.
point The ultrasound beam is infinite thin in its thickness and lateral direction.
point The detected echo comes from the shortest sound path between reflector and transducer.
point The ultrasound echo is originated by the last generated sound pulse.
point The amplitudes of the echoes are proportional to the difference of the acoustical impedance caused by different tissue layers.
A lot of steps can be taken to prevent artifacts and to improve image quality, for example beamforming is used to focus the ultrasound beam, and contrast agents decrease the reflectivity of the undesired interfaces or increase the backscattered echoes from the desired regions.
See also Coded Excitation, Validation and Refraction Artifact, Q-Value, Ultrasound Phantom, Dead Zone, Narrow Bandwidth.

• View the NEWS results for 'Image Quality' (8).Open this link in a new window.

• View the DATABASE results for 'Image Quality' (35).Open this link in a new window.

 Further Reading:
  News & More:
Guidelines for the Safe Use of Diagnostic Ultrasound(.pdf)Open this link in a new window
   by folk.ntnu.no    
Real-time B-mode ultrasound quality control test procedures a Report of AAPM Ultrasound Task Group No. 1Open this link in a new window
   by www.aapm.org    
  Artifacts I top
If our house be on fire, without inquiring whether it was fired from within or without, we must try to extinguish it.----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
- Thomas Jefferson
 
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