Cardiac Ultrasound Artifacts

Question 1

Speed of sound in tissue?

Answer 1

1,540 m/s

Question 2

Speed of sound in Starr-Edwards mechanical valve ball is __ (higher/lower) than surrounding tisse.

Answer 2

Slower, this makes it look larger and more oval-shaped.

Called propagation speed error artifact.

Question 3

What is a useful tool to determine whether aortic images are artifact or flap?

What type of artifact is this?

Answer 3

M-mode.

Reverberation artifact. There is sometimes a linear artifact in the aorta at twice the distance of LA wall. This is why this artifact typically appears when the aorta is larger than the LA (so that doule the LA distance falls within the aorta). If moves with aortic posterior wall, most likely artifact. If independent movement, likely real.

Question 4

__ results from repeated reflections off the transducer or other strong reflectors.

Answer 4

Reverberation artifacts, Intensity will decrease with distance travelled. Equally spaced and parallel to the main sound beam.

Question 5

What are comet tail artifacts?

Answer 5

Reverberation-type artifact that results in a solid hyperechoic beam of ultrasound distal to the object. Similar to reverberation but does not have equally spaced lines of decreasing intensity. Violation of time of flight and speed of sound assumptions.

Seen commonly with mechanical valves.

Question 6

Where do beam width artifacts occur?

Answer 6

Distal to the focal zone where lateral resolution is the least optimal.

Question 7

Snell’s Law

Answer 7

Describes the principle by which refraction of ultrasound occurs and contributes to the development of reverberation-type artifacts.

SL = sin(transmission angle)/sin(incident angle) = speed of medium 2/speed of medium 1

Question 8

Side lobe artifact

Answer 8

Artifact that appears lateral to the real object. Caused by some of the ultrasound beam being to the side of the central beam. These weak signals will return to the transducer if they hit a strongly reflective object. Will falsely appear within the central beam of the transducer.

Question 9

Refraction artifact

Answer 9

Produced when the transmitted ultrasound beam is deviated from its straight path line due to crossing a boundary between two media with different propagation velocities. Will result in a duplicate structure displayed in the wrong location.

Question 10

How does range ambiguity occur?

Answer 10

Occurs when echoes from deep structures created by a first pulse arrive AFTER the second pulse has been emitted.

Question 11

Mirror-image artifact

Answer 11

occurs when doppler gains are set too high and causes a flow signal (usually less intense than real) on the opposite side of the baseline.

Question 12

Ring-down artifact

Answer 12

Occurs when the sound beam hits a strong reflector that causes multiple reverberations with distal echogenic lines. Often caused by gas particles. Looks similar to comet-tail, tbh.

Question 13

Difference between shielding and shadowing?

Answer 13

Shielding refers to the presence of bright beam ultrasound that obscures the visualization of tissue beyond.

Shadowing refers to attenuation and black echoes after a strong reflector.

Question 14

Ghosting artifact

Answer 14

Develops with color doppler, refers to color doppler that is distorted beyond anatomic borders due to multiple reflections.