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anisotropic nerve identification in PNB 

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anisotropic nerve identification in PNB 

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During peripheral nerve block procedures, tilting the probe can highlight highly aniostropic structures like nerves.

In these side-by- side sonograms the sciatic nerve is seen in transverse (short-axis) view. Tilting the transducer from neutral position (A) to approximately 10 degrees (B) markedly reduces the received echoes from the nerve.

https://aneskey.com/introduction-to-ultrasound-assisted-regional-anesthesia-techniques/

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Reverberation: coin in stomach

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posterior acoustic enhancement.

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Mirror image artifact - kidney 'reflected in diaphragm

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https://youtu.be/3H22-AyblIktmrk1

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0:00 / 11:32•Watch full video

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Shadowing artefacts of stones in the gallbladder and enhancement artefacts caused by the fluid in the gallbladder.

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The double aorta artifact is a relatively common ultrasound artifact, which can appear both on standard B-mode and color Doppler imaging, resulting in an artifactually duplicated abdominal aorta in the transverse plane. Knowledge of this artifact is paramount as potential differential diagnoses include life threatening conditions (e.g. aortic dissection).

The artifact is caused by the differential refraction of the ultrasound beam while passing through the relatively echogenic rectus abdominis muscles, and the comparatively hypoechoic fatty tissue underneath. The interface between these tissues creates an acoustic prism effect. The artifact primarily affects curvilinear transducers ¹.

Partially, or less commonly completely duplicated, "double barrel" appearance of the abdominal aorta in the transverse plane is characteristic, which also affects color Doppler imaging. Adjacent structures (e.g. anterior vertebral echo) are duplicated too, but this is usually harder to appreciate.

The artifact can be diminished by changing the angle of insonation in a way that the beam no longer passes through the "acoustic prism" formed by the rectus abdominis muscles and the fatty tissue beneath the linea alba. Rotating the probe into the sagittal plane has a similar result. Note that pulsed wave Doppler ultrasound curves are not affected by this artifact, and will display normal spectral waveform, which also differentiates this phenomenon from its mimickers.

The artifact is more common in younger, athletic patients, and the duplication is usually incomplete ¹.

Note that this phenomenon (albeit rarely) can be encountered in other regions, e.g. during echocardiography 2.

ADVERTISEMENT: Supporters see fewer/no ads

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Double aorta artifact (ultrasound) | Radiology Reference Article | Radiopaedia.org

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The double aorta artifact is a relatively common ultrasound artifact, which can appear both on standard B-mode and color Doppler imaging, resulting in an artifactually duplicated abdominal aorta in the transverse plane. Knowledge of this artifact is paramount as potential differential diagnoses include life threatening conditions (e.g. aortic dissection).

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US image processing assumes that the echoes detected originated from within the main ultrasound beam. The ultrasound beam exits the transducer as a complex three-dimensional bow-tie shape with additional off-axis low-energy beams, which are referred to as side lobes and grating lobes (,3,,4) (,Fig 1). A strong reflector located outside of the main ultrasound beam may generate echoes that are detectable by the transducer. These echoes will be falsely displayed as having originated from within the main beam. This form of artifact is more likely to be recognized when the misplaced echoes overlap an expected anechoic structure (,2).

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US image processing assumes that the echoes detected originated from within the main ultrasound beam. The ultrasound beam exits the transducer as a complex three-dimensional bow-tie shape with additional off-axis low-energy beams, which are referred to as side lobes and grating lobes (,3,,4) (,Fig 1). A strong reflector located outside of the main ultrasound beam may generate echoes that are detectable by the transducer. These echoes will be falsely displayed as having originated from within the main beam. This form of artifact is more likely to be recognized when the misplaced echoes overlap an expected anechoic structure (,2).

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US image processing assumes that the echoes detected originated from within the main ultrasound beam. The ultrasound beam exits the transducer as a complex three-dimensional bow-tie shape with additional off-axis low-energy beams, which are referred to as side lobes and grating lobes (,3,,4) (,Fig 1). A strong reflector located outside of the main ultrasound beam may generate echoes that are detectable by the transducer. These echoes will be falsely displayed as having originated from within the main beam. This form of artifact is more likely to be recognized when the misplaced echoes overlap an expected anechoic structure (,2).

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Shadow Artefact can cause an acoustic shadow past a structure that may be fluid filled like a cyst.  This causes a shadow beneath the structure with the inability to see what is past it. 

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Shadow Artefact can cause an acoustic shadow past a structure that may be fluid filled like a cyst.  This causes a shadow beneath the structure with the inability to see what is past it. 

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“Ultrasound image slice from 3D ultrasound volume acquired prior to start of resection (a), towards the end of resection with some tumor tissue remaining (b), and after completed tumor resection (c). Notice the signal enhancement below the cavity (marked with arrows) seen in c, which is not observed in a or b. Hence, it is very likely that the enhancement is an artefact and not remaining tumor” (Selbekk, et. al, 2005, p. 977).

Selbekk, T.,  Jakola, A.S., Solheim, O., Johansen, T.F., Lindseth F., Reinertsen I., Unsgård G. (2013). Ultrasound imaging in neurosurgery: approaches to minimize surgically induced image artefacts for improved resection control. Acta Neurochir (2013) DOI 10.1007/s00701-013-1647-7. https://link.springer.com/content/pdf/10.1007/s00701-013-1647-7.pdf

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Artifacts are any alterations in the image which do not represent an actual image of the examined area. They may be produced by technical imaging errors or result from the complex interaction of the ultrasound with biological tissues.

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Artifacts are any alterations in the image which do not represent an actual image of the examined area. They may be produced by technical imaging errors or result from the complex interaction of the ultrasound with biological tissues.

# data[].attributes.headline
Artifacts are any alterations in the image which do not represent an actual image of the examined area. They may be produced by technical imaging errors or result from the complex interaction of the ultrasound with biological tissues.

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Artifacts are any alterations in the image which do not represent an actual image of the examined area. They may be produced by technical imaging errors or result from the complex interaction of the ultrasound with biological tissues.

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Small pocket of fluid trapped by surrounding air bubbles is the source. The ultrasound waves hit a pocket of trapped fluid, and sound waves are produced within the fluid and a continuous sound wave is transmitted back to the transducer

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Radiopaedia.org google this
4 D imaging

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Life in the Fast Lane * LITFL * Medical Blog

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Reverberation Artefact Refresh

An ultrasound machine assumes a single pulse of ultrasound enters the tissues, is reflected off a structure, and returns directly to the transducer for interpretation. When this does not occur ultrasound artefacts are created.

Not infrequently an ultrasound pulse encounters two parallel reflective surfaces lying perpendicular to its path. Some of the pulse becomes caught between the two surfaces, bouncing forwards and backwards before returning in increments, between each reverberation, to the transducer. This reverberation causes a repetitive artefact on the ultrasound image.

The appearance of the reverberation artefact depends on:

The size of the two reflective surfaces

The distance between the two reflective surfaces (long vs short path reverberation artefacts)

How much ultrasound energy is lost - dissipated or attenuated, between each re-reflection.

Comet tail artefact

Comet tail artefact is a short path reverberation artefact that weakens with each reverberation, resulting in a vertical echogenic artefact that rapidly fades as it continues in to the ultrasound image.

Normal lung. Sliding is seen as the two pleural surfaces move against each other through the respiratory cycle. Originating at the pleural surface is an echogenic vertical comet tail artefact. The reverberation focus is a tiny area of interstitial fibrous tissue or fluid with non parallel surfaces.

How comet tail artefact is formed

The ultrasound pulse is trapped between reflective surfaces that are not parallel. Some of the reverberating pulse is reflected back to the transducer but much more is reflected off in other directions.

With each reverberation the ultrasound pulse returning back to the probe is much weaker and it quickly fades.

Alternatively the ultrasound pulse is trapped between two parallel surfaces in a tissue that rapidly attenuates the energy of the pulse. Each returning pulse is therefore significantly weaker and the reverberation artefact fades.

Short path reverberation artefacts explained

Further Reading

An Emergency physician based in Perth, Western Australia. Professionally my passion lies in integrating advanced diagnostic and procedural ultrasound into clinical assessment and management of the undifferentiated patient. Sharing hard fought knowledge with innovative educational techniques to ensure knowledge translation and dissemination is my goal. Family, wild coastlines, native forests, and tinkering in the shed fills the rest of my contented time. | | SonoCPD | Ultrasound library | Top 100 @thesonocave |

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Comet tail artefact * LITFL * Ultrasound Library

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Reverberation Artefact Refresh An ultrasound machine assumes a single pulse of ultrasound enters the tissues, is reflected off a structure, and returns directly to the transducer for interpretation. When this does not occur ultrasound artefacts are created. Not infrequently an ultrasound pulse encounters two parallel reflective surfaces lying perpendicular to its path.

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Ring down artifact is a special type of resonance artifact. Its appearance is similar to the ladder-like reverberation of comet-tail artifact, but it is produced by a completely different mechanism.

The artifact is only associated with gas bubbles, and occurs when an ultrasound pulse encounters a "horn" or "bugle" shaped fluid collection that is trapped between an inverted tetrahedron of 4 bubbles (3 on top and 1 nestled deep to them). The trapped fluid resonates, emitting a continuous signal back to the transducer. Whereas the transducer pulse is broad spectrum, the returning signal consists of one or more discrete (resonant) frequencies. "Beats" between these frequencies produce the variable appearance of the ring down. There is no "reverberation" ( i.e. multiple reflectances).

This artifact can be eliminated by angling the ultrasound probe.

See also

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Ring down artifact | Radiology Reference Article | Radiopaedia.org

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Ring down artifact is a special type of resonance artifact. Its appearance is similar to the ladder-like reverberation of comet-tail artifact, but it is produced by a completely different mechanism.

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differing propagation speeds and oblique incidence bend the Ultrasound beam and can appear as duplicate structures, edge shadowing, or laterally displaced structures

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REFRACTION ARTIFACTS

differing progagation speeds and oblique incidence bend the U/S beam and can appear as duplicate structures, edge shadowing, or laterally displaced structures.

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REFRACTION ARTIFACTS

differing progagation speeds and oblique incidence bend the U/S beam and can appear as duplicate structures, edge shadowing, or laterally displaced structures.

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Ultrasound artifacts - Beam width artifact

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Ultrasound artifacts - Beam width artifact

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The beam width artifact is created when echoes from objects in the peripheral field are displayed as overlapping the object of interest. This artifact can be resolved by adjusting the focal zone and centering the object of interest.

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Your access to the NCBI website at www.ncbi.nlm.nih.gov has been temporarily blocked due to a possible misuse/abuse situation involving your site. This is not an indication of a security issue such as a virus or attack. It could be something as simple as a run away script or learning how to better use E-utilities, http://www.ncbi.nlm.nih.gov/books/NBK25497/, for more efficient work such that your work does not impact the ability of other researchers to also use our site. To restore access and understand how to better interact with our site to avoid this in the future, please have your system administrator contact info@ncbi.nlm.nih.gov.

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Your access to the NCBI website at www.ncbi.nlm.nih.gov has been temporarily blocked due to a possible misuse/abuse situation involving your site. This is not an indication of a security issue such as a virus or attack.

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The comet-tail artifact is a grey-scale ultrasound finding seen when small calcific / crystalline / highly reflective objects are interrogated and is believed to be a special form of reverberation artifact.

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The comet-tail artifact is a grey-scale ultrasound finding seen when small calcific / crystalline / highly reflective objects are interrogated and is believed to be a special form of reverberation artifact.

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This type of artifact is caused by unshielded  electrical equipment that is too close to the ultrasound machine, causing arc-like moving bands on the image. This can also be caused by a probe malfunction.
https://radiopaedia.org/articles/electrical-interference-artifact-ultrasound?lang=gb

The image shows an ultrasound image of a paravalvular leak, the artifact in this case is clearly recognisable, therefore doesn't have an impact on determining a diagnosis for the patient.

Image:
https://onlinelibrary.wiley.com/cms/asset/2c600524-dc84-4873-9a15-2242cb5bcab2/echo14116-fig-0017-m.jpg

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anhencement artefacts

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Edge artefacts

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Peer reviewed article with images.

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Week 4 - Ultrasound Artifacts with Images

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All artefacts are explained and you can click on link to see images

https://radiopaedia.org/articles/ultrasound-artifacts-3

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Ringdown Artifact

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Figure 4: Example of a ring- down artifact. | Basic physics ...
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Central Venous Catheterization | US Guided Technique
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Pegasus Lectures, Inc. COPYRIGHT 2006 Volume II Companion ...
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Figure 4: Example of a ring- down artifact. | Basic physics ...377 × 328 - 20k - jpgpinterest.ca 9: Artefactos en imágenes IVUS. (a) Ring- down artifact. (b ...600 × 600 - 185k - pngresearchgate.net Central Venous Catheterization | US Guided Technique250 × 200 - 31k - jpgmed.uottawa.ca A ring- down artifact generated by imaging a needle.

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Sheila K

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Imaging Ultrasound Artifacts.
Sheila K.

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Two-dimensional grayscale imaging artifacts arise when the data acquisition and signal-processing assumptions made by the ultrasound imaging system are violated ( Table 3); these were recently discussed by Pamnani and Skubas.8 In evaluating artifacts, the importance of obtaining multiple views of the same object cannot be stressed enough, because the persistence of a finding in multiple views decreases the likelihood that it is an artifact ( Table 4).

TWO-DIMENSIONAL ULTRASOUND ARTIFACTS

Shadowing and Enhancement Artifact

Anechoic or hypoechoic regions may be the result of shadowing. Conversely, hyperechoic areas on an image display may be the result of enhancement. In both instances, the assumption that the ultrasound is attenuated uniformly is violated. Enhancement artifacts resulting in the appearance of extra-anatomic features may occur when the ultrasound beam travels through tissue that attenuates less than its surroundings.9 Shadowing occurs when the transmitting beam encounters a structure with high attenuating properties.10 For example, the highly reflective portions of prosthetic or heavily calcified valves prevent the comprehensive evaluation of left ventricular wall motion in the midesophageal views by displaying anechoic regions distal to the valves ( Fig. 3; Supplemental Digital Content 1, Supplemental Video 1, http://links.lww.com/AA/B289). Evaluating the left ventricle from the transgastric or deep transgastric views will remove the reflector (i.e., valve) from the path of the area of interest and eliminate shadowing (Supplemental Digital Content 2, Supplemental Video 2, http://links.lww.com/AA/B290).

Reverberation Artifact

Reverberation results in a pattern of regularly spaced artifacts; the spacing represents the distance between the proximal and the distal reflector ( Fig. 4, left). The intensity of the reverberation is directly related to the difference in acoustic impedance between the reflector and its surroundings11 and, when intense, reverberations may obscure imaging of anatomic structures distal to the reflectors. When the distance between the reflectors is small, the artifact appears as a smear of signal rather than a discrete anatomic feature. In this case, these reverberations are referred to as "comet-tail" or "ring-down" artifacts.11,12 In reverberations, the assumption that the ultrasound has returned to the transducer after only a single reflection is violated. With reverberation artifacts, the ultrasound beam bounces multiple times between 2 highly reflective surfaces during the listening phase before returning to the transducer.9 Changing the probe position (e.g., from midesophageal to transgastric views) will eliminate these artifacts.

Ring-down artifacts occur when bubbles within a fluid background reflect or resonate sound waves ( Fig. 4, right).12 The appearance of ring-down artifacts should alert the echocardiographer to the presence of gas (e.g., air embolism or post-cardiopulmonary bypass air; Fig. 5; Supplemental Digital Content 3, Supplemental Video 3, http://links.lww.com/AA/B291). In patients who may benefit from electrical cardioversion for atrial fibrillation, the distinction between left atrial appendage thrombi and a reverberation artifact is an important one to make.13,14 Similarly, many linear artifacts mimicking aortic dissections have been attributed to reverberation of the posterior wall,15-24 particularly in a dilated ascending aorta,22 and may result in unnecessary interventions. Comet-tail artifacts have been reported in association with left atrial catheters25 but can occur in the presence of any closely spaced reflectors, such as pacing wires or pulmonary artery catheters. They are often seen radiating from the distal wall of a descending aorta ( Fig. 6; Supplemental Digital Content 4, Supplemental Video 4, http://links.lww.com/AA/B292).

Mirror-Image Artifact

Mirror-image artifacts create the appearance of additional structures on the monitor display. Typically, the duplicated structure is deeper, equidistant, and occasionally lateral to the reflector. Similar to reverberation artifacts, mirror-image artifacts occur when the assumption that the ultrasound echo returns to the transducer after only a single reflection is violated. Instead, the ultrasound beam first hits a large, smooth (mirror-like) reflector during the transmission phase, which directs it to a second reflector (i.e., target). The beam then bounces from the target back to the mirror-like surface on its return to the probe ( Fig. 7). Identifying the smooth reflector using multiple imaging planes will help to differentiate true extra structures from mirror-image artifacts. Similar to the artifacts discussed earlier, changing the probe position (e.g., from midesophageal to transgastric views) to remove the reflector from the path of the area of interest will eliminate these artifacts. Examples of mirror-image artifacts are foreign objects in the left ventricle26,27 or dissections in the descending aorta.22

Beam Width Artifacts

Lateral resolution refers to the ability to distinguish 2 or more structures side-by-side on the monitor as separate. When the ultrasound beam widens distal to the focal zone, 2 separate side-by-side structures may appear as 1 continuous structure on the image display. Poor lateral resolution may be the result of beam width artifacts. These artifacts occur when the assumption that ultrasound waves are infinitely thin throughout is violated. Adjusting the focal zone with the focus knob may help to eliminate these artifacts ( Fig. 8). Beam width artifacts have been attributed to false positives for thrombus in the left atrial appendage for patients undergoing TEE with atrial fibrillation.28

Side and Grating Lobe Artifacts

Side and grating lobe artifacts result in the blurring of the edges of a displayed object (reduce lateral resolution); the assumption that the ultrasound waves are infinitely thin is violated. Grating and side lobes appear similarly around the main beam, but their mechanisms of origin differ ( Fig. 9).29 Side and grating lobes are secondary beams around the central ultrasound beam and are produced by nonaxial vibrations of the piezoelectric elements.

In clinical practice, it can be difficult to differentiate between side and grating lobe artifacts.30 A blurred pacemaker wire or pulmonary artery catheter is considered either a beam width or a side-lobe artifact.31

Side-lobe artifacts are echoes extending lateral of their targets across the arc of the sector scan. They are also part of the differential diagnosis for masses in the left atrial appendage.32 Side-lobe-generated artifacts may contribute to making normal, stented bioprosthetic aortic valves appear abnormally bent.33 Harmonic imaging may reduce the echoes from the side and grating lobes of the ultrasound beam (Supplemental Digital Content 5, Supplemental Video 5, http://links.lww.com/AA/B293).7,34

Refraction Artifact

Refraction occurs rarely in TEE and appears as the misregistration, omission, or side-by-side split imaging of an object ( Fig. 10). Refraction occurs when the ultrasound beam propagates at a different angle from its original path as it travels through tissue interfaces with different propagation speeds. In refraction, the assumption that the ultrasound pulses travel in a straight line is violated. It may disappear when the probe is moved toward areas with similar propagation speeds (e.g., blood next to soft tissue) or by changing the imaging plane. This artifact has been noted to mimic a pseudoaneurysm of the aorta.35 It occurs more frequently during transthoracic echocardiogram36-39 because the ultrasound wave is more likely to travel through tissue interfaces with large differences in propagation speed (e.g., fat versus muscle) compared with TEE.

SPECTRAL AND COLOR FLOW DOPPLER ARTIFACTS

Doppler Shift

When a pulse emitted from the transducer strikes a moving red blood cell, the difference between the transmitted and the reflected frequency (i.e., Doppler shift) is proportional to the speed of the red blood cell. This is expressed in the mathematical formula for Doppler shift where the blood flow velocity (vel) is vel = [(Fr − Ft) × (C)]/[2Ft × cosine θ] and Ft = frequency of transmitted ultrasound beam, Fr = frequency of reflected ultrasound beam, C = velocity of sound in human tissue, assumed to be constant at 1540 m/s, θ = angle between the Doppler beam and the direction of blood flow. In continuous wave Doppler (CWD) and pulsed wave Doppler (PWD), the velocity calculated from the Doppler shift is graphed against time in the x-axis. The velocities above the zero velocity baseline correspond to blood flowing toward the transducer, whereas velocities below the zero velocity baseline correspond to blood flowing away from the transducer. In color flow Doppler (CFD), a sector is superimposed on the 2D image, and the velocity range within this sector is depicted with a preset gradation, with the lightest colors representing highest velocities. Most ultrasound systems have default CFD settings, such that blue represents flow away from the transducer and red represents flow toward the transducer (mnemonic: blue away, red toward [BART]).40

The physics of each modality have been thoroughly reviewed.41,42 In terms of clinical application, CWD measures all blood velocities along the ultrasound beam, whereas PWD and CFD detect velocity information at a specific location. Artifacts in spectral Doppler and CFD are summarized in Table 5 and will be discussed in more detail later.

Aliasing

Aliasing, also called Doppler shift ambiguity, appears as a "wrap-around" of the velocity in PWD and CFD. In PWD, the velocity continues beyond the limit of the scale and reappears at the opposite part of the scale. In CFD, the wrap-around is displayed as patches of light blue adjacent to patches of bright yellow ( Fig. 11). In the presence of aliasing, the displayed velocities cannot be resolved.

Aliasing occurs because the velocity that can be measured accurately by PWD and CFD is limited; this maximum resolvable velocity corresponds to a Doppler shift equal to half of the pulse repetition frequency (i.e., Nyquist limit).42 Aliasing may be reduced by shifting the baseline, maximizing the velocity scale, decreasing the sector depth, decreasing the transmitted ultrasound frequency, or decreasing the sector.43

The ability to use aliasing may be clinically useful in detecting a turbulent lesion across valves and vessels,44-46 as well as in diagnosing diastolic dysfunction and the severity of valvular regurgitation. When aliasing is used for the subjective grading of regurgitation or stenosis, using a low-velocity scale (i.e., setting the Nyquist limit too low) will make the flow appear worse than it is (Supplemental Digital Content 6, Supplemental Video 6, http://links.lww.com/AA/B294).

Aliasing does not occur with CWD because separate elements on the probe transmit while others simultaneously "listen." This eliminates the limitation set by the pulse repetition frequencies (i.e., pulses emitted per second).

Spectral Doppler Mirroring

Spectral Doppler mirror-image artifacts appear as a duplicate of the velocity spectrum above and below the baseline. Causes of spectral Doppler mirror-image artifacts are cross talk and directional ambiguity. Cross talk results from erroneous signal transfers when the echo exceeds the operating range of the circuit and results in the appearance of velocity on both sides of the baseline. On one side, the velocity is usually more intense and brighter (i.e., true Doppler shift) than the one on the other side ( Fig. 12A). Reducing the Doppler gain or output power may eliminate the artifact. Directional ambiguity occurs when the Doppler angle is near 90°. Also known as "indeterminate flow direction,"47 the intensity on both sides of the baseline is relatively uniform ( Fig. 12B). When Doppler spectral mirroring is related to directional ambiguity, gain and power have little effect on reducing the artifact.

Artifacts in CFD

Artifacts in CFD are due to the same mechanism as in B-mode imaging. Mirror-image artifacts also occur in CFD images. Reflections from a mirror surface do not alter the Doppler shift, but the apparent flow direction (and color coding) may be affected. If the transmitted and reflected pulse encounters the blood flow from the same direction (relative to the flow direction), then the duplicated (mirrored) color Doppler pattern will be the same as the flow inside the true structure. If they encounter the flow from opposing directions, then the Doppler pattern will have the opposite color (i.e., suggesting flow in the opposite direction; Fig. 13; Supplemental Digital Content 7, Supplemental Video 7, http://links.lww.com/AA/B295). This has been seen as a duplication of the right ventricular outflow tract with parallel flow secondary to a thickened pericardium.48 Shadowing is commonly seen in CFD as an area of missing velocity information distal to a strong attenuating object such as a prosthetic valve (Supplemental Digital Content 8, Supplemental Video 8, http://links.lww.com/AA/B296).

Blooming

In "blooming," soft tissues are color-coded as if they contain true blood flow. Also known as "color bleed," this artifact results from abnormally high-gain settings and the artifact may potentially obscure pathology47 such as severe atherosclerosis in the aorta ( Fig. 14). Doppler gain does not affect the intensity of the transmitted pulse.

Pseudoflow

Motion of fluids other than blood, such as ascites, amniotic fluid, pleural effusion, and urine can be imaged with CFD; this "pseudoflow" is an artifact because spectral imaging will not typically show characteristic arterial or venous waveforms.47 Pericardial effusions seen during an echocardiographic examination may demonstrate flow because of their proximity to the heart ( Fig. 15; Supplemental Digital Content 9, Supplemental Video 9, http://links.lww.com/AA/B297).

Twinkling

Used for diagnostic purposes in noncardiac imaging,49-51 "twinkling" artifacts are a mosaic of rapidly changing blue and red patches of color near strongly reflective surfaces resulting in patterns that imitate abnormal flow ( Fig. 16; Supplemental Digital Content 10, Supplemental Video 10, http://links.lww.com/AA/B298). Twinkling may be the result of a type of intrinsic scanner noise dubbed "phase" or "clock jitter."52 Spectral Doppler-mode interrogations in the region of this artifact will produce a spectral pattern consistent with noise ( Fig. 16, right). Intracardiac flow that is present throughout the cardiac cycle should also be considered twinkling as part of the differential diagnosis. First described in 1996, this artifact may mimic blood flow,53 such as a regurgitant jet, paravalvular leak, or shunt. It has been described in association with echogenic intracardiac foci in the fetal heart,54 as well as calcified and noncalcified cardiac valves.55 Vena contracta measurements become inaccurate in association with a twinkling artifact.55

THREE-DIMENSIONAL ULTRASOUND ARTIFACTS

Matrix array transducers allow for real-time acquisition and display of cardiac structures in 3D. These transducers are capable of performing 2D multiplanar and live or electrocardiogram-gated 3D imaging of cardiac structures. Three-dimensional ultrasound imaging is subject to the same types of artifacts seen in 2D grayscale images (Supplemental Digital Content 11, Supplemental Video 11, http://links.lww.com/AA/B299), and the mechanisms of artifact formation are similar.56,57 The mechanism for artifacts "specific" to 3D imaging, such as poor elevational resolution and anisotropy, is discussed later and summarized in Table 6.

Name: Huong T. Le, MD.

Name: Nicholas Hangiandreou, PhD.

Name: Robert Timmerman, MD.

Name: Mark J. Rice, MD.

Name: W. Brit Smith, MD.

Name: Lori Deitte, MD.

© 2016 International Anesthesia Research Society

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Two-dimensional grayscale imaging artifacts arise when the data acquisition and signal-processing assumptions made by the ultrasound imaging system are violated ( Table 3); these were recently discussed by Pamnani and Skubas.8 In evaluating artifacts, the importance of obtaining multiple views of the same object cannot be stressed enough, because the persistence of a finding in multiple views decreases the likelihood that it is an artifact ( Table 4).

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REVERBERATION ARTEFACT - coin in the stomach 

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http://medicalplaza.com.ua/

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http://medicalplaza.com.ua/

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ultrasound artefacts images. see www.ultrasound images google and click on images

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ultrasound artefacts images. see www.ultrasound images google and click on images

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short explanation see WWW.Artefact in ultrasound imaging.htm

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Ring Down artifacts is a line or series of parallel bands extending posterior to the collection of gas.
Physics; Ultrasound energy causes resonant vibration of air bubbles.
It occurs posterior to the collection of gas

Tairu.

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A line or series of parallel band extending posterior to pocket of gas collection.
Physics; Ultrasound energy causes resonant vibrations of air bubbles
It occurs posteriorly to the collections of gases e.g pneumobilia.

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 Color doppler twinkling artifact: A misunderstood and useful sign. Hirsch,M et al

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 Color doppler twinkling artifact: A misunderstood and useful sign. Hirsch,M et al

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The “twinkling artifact”, also called “color comet- tail artifact” is visible on Color Doppler Ultrasound (US) examinations as a rapid alternation of color immediately behind a stationary echogenic object, acquiring a false appearance of movement. (Figure 1). It may also manifest when power Doppler and Spectral Doppler scannings are performed, appearing as a sign of heterogeneous spectral expansion composed of adjacent vertical lines with no waveform at all(1,2). Some authors have considered this artifact as an imaging sign, because of its effectiveness and usefulness in promoting pathology detection, especially lithiasis. Revista Chilena de Radiología. Vol. 17 No 2, año 2011; 82-84.

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http://es.slideshare.net/ansaripv/ultrasound-artifact

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http://www.criticalecho.com/content/tutorial-1-basic-physics-ultrasound-and-doppler-phenomenonhttp://www.criticalecho.com/content/tutorial-1-basic-physics-ultrasound-and-doppler-phenomenon

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http://www.u.arizona.edu/~rwitte/PDF/Taljanovic_et_al_2014_Artifacts_in_Musculoskeletal_Ultrasonography.pdf

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http://www.slideshare.net/ICNUploads/signs-in-lung-ultrasound-36821639

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In B-Mode, small tapering lines that diminish distally (compared to B-lines which go to bottom of image). Reverberation artifact
Know your Z-line characteristics:

1. ill defined (not laser like)

2. do not erase A lines

3. do not move with lung sliding

4. do not extend to bottom edge of screen

http://www.critcaresono.com/page.php?page=27

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A-Lines are transeverse linear reverberation artifacts from the pleural line. They are present in 2/3 of normal lung US

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A-Lines are transeverse linear reverberation artifacts from the pleural line. They are present in 2/3 of normal lung US

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http://www.slideshare.net/fergua/focused-thoracic-ultrasound

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In lung US, B-Lines are a "ring down" artifact from small sub-pleural fluid collections. They go to bottom of screen.

1-2 are normal, multiple B-Lines are strongly suggestive of alveolar/interstitial fluid characteristic of lung oedema. Multiple B-Lines may be called lung rockets
Clinical Chest Ultrasound, Bollinger CT. pp79

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Pseudo-Sludge in Gallbladder due to Side Lobe Artefact [Ron Janes]

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Pseudo-Sludge in Gallbladder due to Side Lobe Artefact [Ron Janes]

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- taken from http://www.slideshare.net/shaffar75/ultrasound-of-the-gallbladder

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Speed displacement artifact is a gray scale ultrasound finding that can be identified as an area of focal discontinuity and displacement of an echo deeper than that its actual position in an imaged structure.  The artifact is due to the image processor's assumption that the velocity of the ultrasound beam within the imaged anatomy is uniform and that distance of the structure from the transducer is the sole factor determining that structure's location1.  However, objects imaged by portions of the ultrasound beam slowed by tissue the beam traverses, will appear discontinuous and artificially deep.  A commonly encountered scenario is speed displacement artifact due to slowing of the ultrasound beam by focal fat.

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What do we see, and why do we see it in this way? The artefact is pointed out by the arrow! ^Pim Hendriks - Mentor

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Maybe hard to see, but this Mirror-artefact could cause an entire structure to appear in the wrong place. Do you understand the underlying error? please share! ^Pim Hendriks - Mentor

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Clear example of the Side lobe artefact. Do you understand how this occurs? Please post it on the discussion board ^Pim Hendriks - Mentor

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Mirror artifacts in obstetric ultrasound (Akramul Shishir)

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Mirror artifacts in obstetric ultrasound (Akramul Shishir)

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A mirror artifact in a patient with a singleton gestation at 18 weeks. The image was interpreted as consistent with a twin gestation using transabdominal. The differential diagnosis consisted of an abdominal heterotopic pregnancy. The presence of synchronized but opposite movements of both fetuses, and the blurred image of the second fetus, suggested a mirror artifact. The reflective surface was created by the interface located between a distended rectosigmoid filled with gas and the posterior uterine wall. Mirror artifacts can lead to diagnostic errors. This case illustrates how a distended rectosigmoid colon can generate an image that simulates either a twin gestation or an abdominal heterotopic pregnancy.

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Artefacts occur when any of four assumptions are broken:

1- The speed of sound in tissue is constant

2- Attenuation is constant

3-The beam travels in a straight line

4-Echoes arise from the centre of the beam

http://www.rcemlearning.co.uk/modules/ultrasound-image-acquisition/artefacts/

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Gall Bladder/GallStone.  By Mojitola Idowu

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Gall Bladder/GallStone.  By Mojitola Idowu

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Acoustic shadowing caused by gallstone in the gall bladder.  It can be seen that a shadow its present directly below the gallstone and nothing can be viewed in this region.

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Interesting article regarding the origin of ultrasound artifacts and how to recognize them and prevent them.

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Example of a reverberation artifact and the underlying principle. The artifact can be recognized as multiple linear reflections, which have equal distances to each other and arises in the presence of two parallel, highly reflective surfaces in which the ultrasound beam is reflected back and forth before being detected. This tricks the ultrasound machine, as the time between sending and returning the sound waves is used for depth estimation.

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Example of a beam width artifact, which can be recognized when misplayed echoes overlap an expected anechoic structure, for example, the bladder. Adjusting the focal zone to the level of interest and placing the transducer at the center of the object of interest should help and improve image quality.