Artifacts in echocardiography

Artifacts in Echocardiography

1. Artifacts in Echo Dr Dilzith

2. Contents Artifacts In 2D Echo In Doppler In Colour flow In TEE

3. Artifacts Extraneous US signal that results in appearance of structures that are not actually present Failure to visualize structures that are present An image of a structure that differs in size or shape or both from its actual appearance

4. 2-D Echo

5. Suboptimal Imaging Cause is poor ultrasound tissue penetration Body habitus with interposition of high attenuation tissue. (Lung, Bone) Increased distance ( Adipose tissue) THI can improve the image quality TEE may be required

6. Acoustic Shadowing Reflection of entire US signal by a strong specular reflector Ex: prosthetic valves. Heavily calcified Native structures Contrast containing blood also produces shadowing. Try alternate acoustic window or different transthoracic view TEE may be required

7. Reverberations Multiple linear high amplitude echo signals originating from two strong specular reflectors Results in back and forth reflection Typically, a reverberation artifact that originates from a fixed reflector will not move with the motion of the heart.

8. Beam Width Superimposition of structures within the beam profile (Including side lobes) into a single tomographic image Can be due to strong reflectors at the edge of a larger beam will be superimposed on structures in central zone. Can be due to consequences of varying lateral resolution

9. Range Ambiguity Echo from previous pulse reaches transducer on next cycle. Results in appearance of deep structures closer to the transducer than their actual location Second type of range ambiguity is a double image on the vertical axis Echoes being re-reflected by a structure close to the transducer (ex. Rib) Results in signal received twice normal and can form double image. Range ambiguity can be eliminated by decreasing depth or adjusting the transducer position

10. Refraction Deviation of US signal from a straight path along the scan line. Appearance of side-by-side double image Commonly seen in parasternal short axis view

11. Near Field clutter Also called as “ Ringdown artefact” Arises from high amplitude oscillations of the piezoelectric elements. The artifact is troublesome when trying to identify structures that are particularly close to the transducer Greatly reduced in modern day systems

12. Doppler Artifacts

13. Velocity Underestimation Due to non-parallel intercept angle between the US beam and direction of blood flow

14. Signal Aliasing Inability to measure maximum velocity Can be due to non-laminar disturbed flow and high velocity laminar flow Can be controlled by using low-frequency, change Nyquist limit and use of CW doppler

15. Beam width Superimposition of Doppler signals from adjacent flows Beam width artifacts in Doppler imaging can be clinically useful . beam width artifact often has less desirable effects . Ex: a large sample volume may hinder one's ability to distinguish aortic stenosis from mitral regurgitation .

16. Range ambiguity It’s a speed of sound artefact Doppler signals from more than one depth along the US beam are recorded. 1.misregistration of targets 2.distortion of interfaces 3.errors in size and 4.defocusing of the ultrasound beam . It can be reduced by decreasing the depth or width to the minimum required

17. Mirror Imaging Also called as “Cross Talk” Such mirror images are usually less intense but similar in most other features to the actual signal. can be reduced by decreasing the power output or gain and optimizing the alignment of the Doppler beam with the flow direction.

18. Transit Time Effect Change in the velocity of the US wave as it passes through a moving medium results in overestimation of Doppler shifts Results in broadening of the velocity range at a given time point. (Blurring on the vertical axis)

19. Colour Doppler

20. Shadowing and Ghosting Shadowing:- may occur, masking color flow information beyond strong reflectors . Ghosting:- is a phenomenon in which brief patterns of color are painted over large regions of the image. Ghosts are usually a solid color (either red or blue) and bleed into the tissue area of the image. These are produced by the motion of strong reflectors such as prosthetic valves.

21. Background Noise Also called as Gain setting artifacts Too much gain can create a mosaic distribution of color signals throughout the image. Too little gain eliminates all but the strongest Doppler signals and may lead to significant underestimation. Gain level just below the random background noise can optimize the flow signal

22. Other artifacts .. Intercept angle : Change in colour (or absence at 90 degrees) due to angle between flowstream and US beam Aliasing : On colour flow results in “wraparound” of the velocity signal. Electronic interference: Instrument dependent

23. In TEE

24. Multiple reflections

25. Misplaced reflections

26. Thank You!!