Ultrasound is used for many reasons, including to: View the uterus and ovaries during pregnancy and monitor the developing baby's health Diagnose gallbladder disease Evaluate blood flow Guide a needle for biopsy or tumor treatment Examine a breast lump Check the thyroid gland Find genital and prostate problems Assess joint inflammation (synovitis) Evaluate metabolic bone disease Before your ultrasound begins, you may be asked to do the following: Remove any jewelry from the area being examined. Remove or reposition some or all of your clothing. Change into a gown. You'll be asked to lie on an examination table. During the procedure Gel is applied to your skin over the area being examined. It helps prevent air pockets, which can block the sound waves that create the images. This safe, water-based gel is easy to remove from skin and, if needed, clothing. A trained technician (sonographer) presses a small, hand-held device (transducer) against the area being studied and moves it as needed to capture the images. The transducer sends sound waves into your body, collects the ones that bounce back and sends them to a computer, which creates the images. Sometimes, ultrasounds are done inside your body. In this case, the transducer is attached to a probe that's inserted into a natural opening in your body. Examples include: Transesophageal echocardiogram. A transducer, inserted into the esophagus, obtains heart images. It's usually done while under sedation. Transrectal ultrasound. This test creates images of the prostate by placing a special transducer into the rectum. Transvaginal ultrasound. A special transducer is gently inserted into the vagina to look at the uterus and ovaries. Ultrasound is usually painless. However, you may experience mild discomfort as the sonographer guides the transducer over your body, especially if you're required to have a full bladder, or inserts it into your body. A typical ultrasound exam takes from 30 minutes to an hour. Results When your exam is complete, a doctor trained to interpret imaging studies (radiologist) analyzes the images and sends a report to your doctor. Your doctor will share the results with you. You should be able to return to normal activities immediately after an ultrasound.

1. DR. DHARMENDER
JUNIOR RESIDENT
DEPTT. OF RADIODIAGNOSIS
PGIMS ROHTAK

2.  Artifact is used to describe any part of an image that
does not accurately represent the anatomic structures
present within the subject being evaluated.
 In ultrasonography (US), artifacts may cause structures
to appear in an image that are not present
anatomically or a structure that is present anatomically
may be missing from the image. US artifacts may also
show structures as present but incorrect in location,
size, or brightness.
 US is prone to numerous imaging artifacts, and these
are commonly encountered in clinical practice.
Artifacts have the potential to interfere with image
interpretation.

3. ARTIFACT
PROPAGATION
VELOCITY ARTIFACT
ATTENUATION ERRORS
PATH OF SOUND-
RELATED
GAS-RELATED
ARTIFACTS
BEAM PROFILE–
RELATED
ARTIFACTS
DOPPLER
IMAGING
ARTIFACTS
 Shadowing
 Increased Through
Transmission
 Mirror Image Artifact
 Comet-Tail Artifact
 Refraction
 Anisotropy
 Reverberation Artifact
 Reverberation Artifact
 Ring-Down Artifact
 Dirty Shadowing Artifact
 Side Lobe & Grating Lobe
Artifacts
 Partial Volume Averaging
 Loss or Distortion of
Doppler
Information
 Artifactual Vascular Flow
 Tissue Vibration Artifact
 Aliasing and Velocity
Scale Errors
 Spectral Broadening
 Blooming Artifact
 Twinkle Artifact

4. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
SHADOWING
Shadowing results when there is a marked reduction in the
intensity of the ultrasound deep to a strong reflector, attenuator,
or refractor. Clean dark shadows will be seen behind calcified
objects when the focal zone is at or just below the structure
Gallstone With Shadowing Shadowing From Hernia Repair Mesh

5. Shadowing of Intrauterine Device Coned down view of distal neonatal spine shows shadowing from vertebral bodies that
interrupt the linear appearance of the nerve roots
Shadowing From Ovarian Fibroma. This is a slightly less
“clean” shadow since the fibroma is not as dense as a calcified stone.
Edge shadowing artifact behind the posterior aspect of the fetal skull.
The beam bends at curved surface and loses intensity, producing a
shadow

6. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
Increased Through Transmission
The hepatic parenchyma distal to the cysts is falsely displayed as increased in echogenicity (arrows)
secondary to increased through-transmission artifact. The cyst attenuates 7 dB less than the normal tissue, and time gain curve correction for
normal tissue results in over amplification of the signals deep to the cyst, producing increased through transmission of these tissues
Increased through transmission occurs when an
object (such as a cyst) attenuates the sound waves
less than the surrounding tissues.
Nebothian cyst

7. ARTIFACT
PROPAGATION
VELOCITY ARTIFACT
ATTENUATION ERRORS
PATH OF SOUND-
RELATED
GAS-RELATED
ARTIFACTS
BEAM PROFILE–
RELATED
ARTIFACTS
DOPPLER
IMAGING
ARTIFACTS
 Shadowing
 Increased Through
Transmission
 Mirror Image Artifact
 Comet-Tail Artifact
 Refraction
 Anisotropy
 Reverberation Artifact
 Reverberation Artifact
 Ring-Down Artifact
 Dirty Shadowing Artifact
 Side Lobe & Grating Lobe
Artifacts
 Partial Volume Averaging
 Loss or Distortion of
Doppler
Information
 Artifactual Vascular Flow
 Tissue Vibration Artifact
 Aliasing and Velocity
Scale Errors
 Spectral Broadening
 Blooming Artifact
 Twinkle Artifact

8. PATH OF SOUND-RELATED ARTIFACTS
Mirror Image Artifact
Mirror image artifact in sonography is seen when there is
a highly reflective surface in the path of the primary
beam. (e.g. diaphragm)
The primary beam reflects from such a surface (e.g diaphragm ) but instead of directly being received by
the transducer, it encounters another structure (e.g. a nodular lesion) in its path and is reflected back to the highly
reflective surface (e.g. diaphragm). It then again reflects back towards the transducer.
The ultrasound machine makes a false assumption that the returning echo has been reflected once and hence the
delayed echoes are judged as if being returned from a deeper structure, thus giving a mirror artifact on the other
side of the reflective surface.
It is a friendly artifact that allows the sonographer to exclude pleural effusion by the reflection of the liver image
through the diaphragm.
Examples:
 reflection of a liver lesion into the thorax (the commonest example)
 reflection of abdominal ascites mimicking pleural effusion
 duplication of gestational sac (either ghost twin or heterotopic pregnancy) 3
 duplication of the uterus
To avoid this artifact, change the position and angle of scanning to change the angel of insonation of the primary
ultrasound beam.

9. Mirror Image Artifact. Soft tissue–gas interfaces, such as the diaphragm, are excellent
reflectors of the sound beam owing to the large difference in the acoustic impedance
between the two materials. Therefore hepatic structures are frequently seen mirrored
beyond the diaphragm onto the lungs. These two figures show liver parenchyma, hepatic
veins in part A, and a hepatic hemangioma in part B all inversely projected onto lung.

10. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
Comet-Tail Artifact
The comet tail artifact seen when small calcific / crystalline /
highly reflective objects are interrogated and is believed to
be a special form of reverberation artifact.
 Small renal or ureteric calculi
 Small common bile duct stones
 Adenomyomatosis of the gallbladder
 Pancreatic calcifications of chronic pancreatitis
 Testicular microlithiasis (sometimes)
 Thyroid colloid nodules
 Identification of foreign bodies
Surgical clips
Catheter, Needle tips
Debris/glass/metal
Gallbladder adenomyomatosis

11. Comet-Tail Artifact Behind Von Meyenburg Complex
Thyroid colloid cysts

12. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
REFRACTION
A change in velocity of the ultrasound beam as it
travels through two adjacent tissues with different
density and elastic properties may produce a
refraction artifact such as from muscle to fat.

13. Second gestational sac due to refraction artifact “ghosting”
Refraction artifact (arrowheads) is caused by the interfaces between the ruptured tendon edges and hemorrhage.

14. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
Anisotrophy
Anisotropy is an artifact caused by structures that are
composed of bundles of highly reflective fibers
running parallel to each other, such as tendons and
ligaments
The insertion of supraspinatus tendon
artifactually appears hypoechoic due to anisotropy.
“Peritrigonal blush” region of the white matte
(ellipse) appears relatively echogenic

15. PROPAGATION VELOCITY ARTIFACT
ATTENUATION ERRORS
Reverberation Artifact
Reverberation artifact occurs when a strong
reflector runs perpendicular to the direction of the
beam (i.e., parallel to the probe surface), usually
close to the skin surface.
The sound waves may then get partially “trapped” between the reflector and skin, reverberating back and forth and
causing the appearance of multiple regular lines when some of the waves eventually.
Reverberation artifacts arise when the ultrasound signal reflects repeatedly between highly reflective interfaces near
the transducer, resulting in delayed echo return to the transducer. This appears in the image as a series of regularly
spaced echoes at increasing depth reach the probe. Often the reflectors are the skin and subcutaneous
fascia.Reverberation artifact is angle dependent, so moving the transducer slightly will cause a decrease in or
elimination of the artifact.
Reverberation can be helpful during biopsies, to see a needle. If it is distracting, try changing the angle of insonation,
using a different window, or decreasing the gain.
The highly reflective and mirror like surface of the pacemaker (arrow) results in repeated bouncing of sound wave among the probe
surface, pacemaker and skin.

16. ARTIFACT
PROPAGATION
VELOCITY ARTIFACT
ATTENUATION ERRORS
PATH OF SOUND-
RELATED
GAS-RELATED
ARTIFACTS
BEAM PROFILE–
RELATED
ARTIFACTS
DOPPLER
IMAGING
ARTIFACTS
 Shadowing
 Increased Through
Transmission
 Mirror Image Artifact
 Comet-Tail Artifact
 Refraction
 Anisotropy
 Reverberation Artifact
 Reverberation Artifact
 Ring-Down Artifact
 Dirty Shadowing Artifact
 Side Lobe & Grating Lobe
Artifacts
 Partial Volume Averaging
 Loss or Distortion of
Doppler
Information
 Artifactual Vascular Flow
 Tissue Vibration Artifact
 Aliasing and Velocity
Scale Errors
 Spectral Broadening
 Blooming Artifact
 Twinkle Artifact

17. GAS-RELATED ARTIFACTS The physical pressure of the probe on the soft
tissues, such as the abdominal wall, flattens their
shape in the near field, making them perpendicular
to the surface of the probe and the incident
sound beam. Because gases conform to the shape of
their containers, they too will form a linear and
perpendicular interface to the incident sound beam,
especially when in the form of a large bubble. The
highly reflective gas interface will act like a
mirror,resulting in reverberation artifacts.
Reverberation Artifact
Small amount of gas within the
bladder is recognizable by the
reverberation artifact

18. GAS-RELATED ARTIFACTS
Ring-Down Artifact
 Ring-down artifact has been thought to be a variant of
comet tailartifact. This assumption was based on the
often similar appearance
of the two artifacts.
 In ring-down artifact, the transmitted ultrasound
energy causes resonant vibrations within fluid trapped
between a tetrahedron of air bubbles. These vibrations
create a continuous sound wave that is transmitted
back to the transducer .
 This phenomenon is displayed as a line or series of
parallel bands extending posterior to a gas collection.
Despite the similar sonographic appearance, these two
artifacts have separate mechanisms

19. Ring-Down Artifact- Pneumobilia causing ring-down artifact in the biliary tree (A) and gallbladder (B).
A B
Ring-down artifact-peripheral ducts of the liver(C) Iatrogenic air in the bladder introduced at cystoscopy
appears as a nondependent bright region (D)
C D

20. GAS-RELATED ARTIFACTS
Dirty Shadowing Artifact
Dirty shadowing results from a combination of
reflection,reverberation, and ring-down artifacts arising
from multiple variably sized bubbles in foam.

21. Dirty Shadowing Posterior to Emphysematous Cholecystitis
Dirty Shadowing in the Kidney Due to Emphysematous Pyelonephritis

22. ARTIFACT
PROPAGATION
VELOCITY ARTIFACT
ATTENUATION ERRORS
PATH OF SOUND-
RELATED
GAS-RELATED
ARTIFACTS
BEAM PROFILE–
RELATED
ARTIFACTS
DOPPLER
IMAGING
ARTIFACTS
 Shadowing
 Increased Through
Transmission
 Mirror Image Artifact
 Comet-Tail Artifact
 Refraction
 Anisotropy
 Reverberation Artifact
 Reverberation Artifact
 Ring-Down Artifact
 Dirty Shadowing Artifact
 Side Lobe & Grating Lobe
Artifacts
 Partial Volume Averaging
 Loss or Distortion of
Doppler
Information
 Artifactual Vascular Flow
 Tissue Vibration Artifact
 Aliasing and Velocity
Scale Errors
 Spectral Broadening
 Blooming Artifact
 Twinkle Artifact

23. BEAM PROFILE–RELATED ARTIFACTS
Side Lobe & Grating Lobe Artifacts
Side lobe artifacts occur where side lobes reflect sound from
a strong reflector that is outside of the central beam, and
where the echoes are displayed as if they originated from
within the central beam. Side lobe beams are low-intensity
beams that surround the central beam
Side lobe artifacts are echogenic, linear or curvilinear
artifacts. Strong reflectors include bowel gas adjacent to the
gallbladder or urinary bladder.

24. Pseudosludge
Echoes seen in the nondependent portion of
the bladder. Note also the shadowing behind
the bladder stone

25. BEAM PROFILE–RELATED ARTIFACTS
Partial Volume Averaging
The ultrasound beam not only has a complex shape in the imaging
plane but also has a real profile in the third dimension, called
the “elevation plane” or “Z plane.” The ultrasound image appears
as a flat two-dimensional image, but the brightness of each pixel
is representative of the average sum of all the echoes received
within the thickness of the beam in the elevation plane. This
results in echoes being projected in structures that should be
anechoic.
Partial Volume Averaging. The bladder wall is indistinct
in region of this image. It is unclear if there are masses or if this is due
to grating lobe artifact or partial volume artifact or both. Moving the
patient or transducer to avoid bowel gas and putting the focal zone in
the region in question should aid in evaluation. For the area closer to
the patient’s anterior abdominal wall, a higher-frequency transducer
might be helpful

26. ARTIFACT
PROPAGATION
VELOCITY ARTIFACT
ATTENUATION ERRORS
PATH OF SOUND-
RELATED
GAS-RELATED
ARTIFACTS
BEAM PROFILE–
RELATED
ARTIFACTS
DOPPLER
IMAGING
ARTIFACTS
 Shadowing
 Increased Through
Transmission
 Mirror Image Artifact
 Comet-Tail Artifact
 Refraction
 Anisotropy
 Reverberation Artifact
 Reverberation Artifact
 Ring-Down Artifact
 Dirty Shadowing Artifact
 Side Lobe & Grating Lobe
Artifacts
 Partial Volume Averaging
 Loss or Distortion of
Doppler
Information
 Artifactual Vascular Flow
 Tissue Vibration Artifact
 Aliasing and Velocity
Scale Errors
 Spectral Broadening
 Blooming Artifact
 Twinkle Artifact

27. DOPPLER IMAGING ARTIFACTS
Loss or Distortion of Doppler
Information
The appearance of color Doppler signal is affected by several
variables including color-write priority, gray-scale gain, and
pulse repetition frequency. If the color gain is too low, flow
might not be visualized. If the gain is too high, artifactual flow
may be seen in adjacent soft tissues, and thrombus within the
vessel might be missed.
Incorrect gain, wall-filter, and velocity scale can all lead to
loss or distortion of Doppler signal.
Frequency, the rule of thumb is to use a Doppler angle less than
60 degrees (but not 0). Wall filters eliminate low-frequency
noise, but a high setting can lead to loss of signal.
In general, wall filters should be kept at the lowest practical
level, typically in the range of 50 to 100 Hz.

28. A (PRF = 700 Hz) B (PRF = 4500 Hz)
Artifactual Lack of Flow. Color Doppler image of a carotid artery and jugular vein. In (A), the pulse repetition frequency
(PRF) is 700 Hz and there is aliasing in the carotid artery, but slow flow in the jugular vein is seen. In (B), the PRF is 4500 Hz,
eliminating aliasing in the artery but also suppressing the display of the low Doppler frequencies in the internal jugular vein.

29. Artifactual Lack of Flow. (A) Color Doppler image shows flow in the portal vein. (B) When a color image is taken to assess
the common duct, no flow is visible in the portal vein. Note the difference in overall gain in image B.
A B

30. DOPPLER IMAGING ARTIFACTS
Artifactual Vascular Flow
The Doppler effect (shift) is not specific to vascular flow and
occurs with movement of any reflector toward or away from the
ultrasound beam. Fluid or solid tissue motion can mimic
vascular flow. Transmitted pulsations, especially close to the
heart or major arteries, can therefore result in artifactual
appearance of flow within thrombosed veins or avascular areas.
Artifactual vascular flow can also be visualized if the color gain
is too high or the color-write priority is too high.
Color Doppler jets in the bladder use color motion
to indicate that there is flow from each ureteral
orifice

31. Color flow Doppler signal in pleural fluid with debris. (A) Gray-scale sonogram shows left pleural fluid
with much debris. (B) Color flow Doppler signal
A B

32. Color Streaking Artifact. (A) This complicated cyst contains floating punctate echoes that move posteriorly
while being scanned,creating a scintillating appearance on gray-scale sonography. (B) Power Doppler
ultrasound pushes the echoes posteriorly faster and with more energy than does the gray-scale beam. The
echoes move fast enough that color persistence creates the appearance of “color streaking” artifact

33. Flash Artifact From Pulsation. In this image of the left portal vein, note how
transmitted pulsation from the heart causes artifactual flow in the
adjacent liver owing to motion.

34. DOPPLER IMAGING ARTIFACTS
Tissue Vibration Artifact
The color bruit or tissue vibration artifact is a type of color
Doppler ultrasound artifact which results in color signal
overflowing to the perivascular tissues most often caused by
stenosis, AV fistulas, or shunts. Thus, this artifact is useful by
pinpointing areas of potentially pathological blood flow.
Tissue Vibration Artifact From Common Femoral Artery
to Common Femoral Vein Arteriovenous Fistula. Turbulent
flow through the fistula may affect surrounding tissues,
causing a tissue vibration artifact, which may be the first
clue that an arteriovenous fistula (AVF) is present. Common
femoral artery to common femoral vein
AVF. (A)
Color Doppler shows common femoral artery to common
femoral vein AVF. Note the adjacent tissue vibration artifact
(arrowheads).
Turbulent flow causes vibration of the vessel wall and
perivascular soft tissues, resulting in a detectable doppler
shift which typically results in a mixture of red and blue
speckles .
The color bruit is a beneficial artifact that helps with
localizing areas of critical stenosis or turbulent flow due to
other reasons

35. Tissue Vibration Artifact. Postbiopsy arteriovenous fistula. Color Doppler image shows markedly increased lower-pole
blood flow (arrows) with adjacent soft tissue color artifact related to tissue vibration (arrowheads)

36. DOPPLER IMAGING ARTIFACTS
Aliasing and Velocity Scale Errors
Aliasing is an artifact due to undersampling of Doppler
signal, resulting in incorrect estimation of flow velocity
To measure the Doppler frequency shift appropriately by
pulsed Doppler, at least two samples from the cycle are
required (Nyquist limit). If the pulse repetition frequency is
less than twice the maximum
frequency shift produced by movement of the target, aliasing
results. The Doppler signal wraps around either the spectrum
(spectral Doppler) or the color scale (color Doppler). The most
common methods for correcting for aliasing are to shift the
baseline down or up, or increase the pulse repetition
frequency (or velocity scale). A lower-frequency transducer
can also be used to help in correcting for aliasing. As
angulation approaches 90 degrees, directional ambiguity can
occur, suggesting bidirectional flow. Errors in Doppler angle
correction can also lead to misleading assessments of flow
velocity.
Tissue Vibration Artifact. Spectral waveform at site of
superior mesenteric artery stenosis shows very high systolic
velocity, and diastolic velocities of greater than 500 cm/sec.
Color portion of the image shows color bruit consisting of
color outside the vessel near the stenosis site. Color bruit is
believed to be caused by tissue vibration aliasing prevents
precise calculation of the maximum systolic velocity

37. A B
Aliasing (A) appears in the spectral display as a “wraparound” of the higher frequencies to display below
the baseline. (B) In color Doppler display, aliasing results in a wraparound of the frequency color map
from one flow direction to the opposite of unsaturated color.
Aliasing in Superior Mesenteric Artery (SMA) Due to
High-Velocity Flow

38. DOPPLER IMAGING ARTIFACTS
Spectral Broadening
Spectral broadening occurs when there are multiple
different velocities of flow within a vessel. This can be a sign
of stenosis.
However, artifactual spectral broadening can occur owing to
improper positioning of the sample volume near the vessel
wall, use of an excessively large sample volume, or excessive
system gain.
Spectral Broadening. The range of velocities
detected at a given time in the pulse cycle is
reflected in the Doppler spectrum
as spectral broadening. (A) Normal spectrum.
Spectral broadening may arise from turbulent
flow in association with vessel stenosis.
(B and C)
Artifactual spectral broadening may be
produced by improper positioning
of the sample volume near the vessel wall, use
of an excessively large sample volume (B), or
excessive system gain (C)

39. Spectral Broadening. True spectral broadening due to ECA
stenosis.

40. DOPPLER IMAGING ARTIFACTS
Blooming Artifact
Blooming artifact occurs when color reaches beyond the
vessel wall, making the vessels look larger than expected. It
is gain dependent in that lowering the gain will decrease
blooming. It is also wall filter and color-overwrite
dependent, in that increasing the wall filter will decrease the
artifact
Two images of the same carotid artery. In (A) the gain and wall filter are appropriate to show the flow centrallyin the vessel. In (B) the
gain and wall filter have been changed (in a manner beyond what would be used in clinical imaging) to demonstrate how these can
make the vessel “bloom” and appear larger

41. DOPPLER IMAGING ARTIFACTS
Twinkle Artifact
Twinkle artifact occurs as a focus of alternating
colors on Doppler signal behind a reflective object
(such as a calculus), which gives the appearance of
turbulent blood flow 2. It appears with or without an
associated color comet tail artifact.
The underlying mechanism of this artifact is thought
to be a result of inherent noise within the ultrasound
scanner, specifically phase (a.k.a. clock) jitter within
the Doppler electronics
Twinkling artifact is more sensitive for detection of
small stones (e.g. urolithiasis,cholelithiasis ) than is
acoustic shadowing.

42. Ureterovesical junction stone