Tutorial on Ultrasound Imaging Artefacts

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Tutorial on Ultrasound Imaging Artefacts

• Uni of SA
• Ultrasound Physics 1
• Prepared by Sean McPeake

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Artefact 1
The artefact seen deep to the measured structure
on the image below is one of the important
criteria in the diagnosis of this lesion. 1
Name the artefact and the lesion. 2 Discuss the
formation of the artefact.
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The artefact in question has aided in the
diagnosis of this lesion ( ) too!
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Artefact 2
1 Name the artefact seen deep to the renal
calculus in Image A and discuss its
formation. When a calculus is small, like the one
seen at the left ureteric orifice in Image B,
little or no shadowing will be seen. 2
Approximately how big must a calculus be to cast
a shadow? 3 Why is the depth of the calculus
important? 4 What imaging parameter changes
could be made to improve the visualisation of the
shadow behind such a small calculus? Explain your
answers.
Image A
Image B
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Artefact 2 may be seen deep to calculi as in
Image A but it may also be seen deep to bowel gas
as in Image B. Differentiate between the two
shadows seen
Image B
Image A
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Artefact 3
This image is of a surgical staple in the dorsal
aspect of a foot. The staple itself is the linear
echogenic structure a little under 1 cm long.
1 Name the artefact seen deep to the
staple. 2 Explain in detail the formation of
this artefact
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In image A B the same small cortical cyst in
the left kidney is being imaged. For Image A the
transducer was placed directly over the cyst in
both the beamwidth and slice thickness planes.
For Image B an angled approach was used. Explain
the relative masking of the cyst in Image A.
Image A
Image B
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Artefact 4
In the posterior aspect of this urinary bladder
false echoes (blue arrow) are shown within the
lumen of the bladder. Name and discuss the
formation of this artefact More anteriorly in the
bladder further false echoes are shown (red
arrow) Name and discuss the cause of these echoes.
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Artefact 5
This image was taken at right angles to the one
on the previous slide. What do you think is the
cause of the false echoes seen in the posterior
aspect of the bladder? Name the artefact involved
and contrast it to the artefact seen in the
posterior part of the bladder on the previous
slide. Complete this statement. Artefacts 4 5
are both P _ _ _ _ _ _ V _ _ _ _ _ artefacts
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Artefact 6
Name and with the aid of a sketch describe the
formation of the artefact causing the curvilinear
band of false echoes through the urinary bladder
in the image below.
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Artefact 7
Images A B are transverse images of the
abdominal aorta. For Image A the transducer was
placed slightly away from the midline, whereas in
Image B the transducer was on the abdominal
midline. Explain with the aid of a diagram why
the aorta has a double barrel appearance in
Image B.
Image A
Image B
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From most angles there seems to be only one
calculus in the left VUJ, but when scanning in
the midline there at times appears to be two.
Explain.
MIDLINE SCAN
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Abnormal thickening of the nuchal fold gt6mm at
18-20 weeks gestation has a strong association
with chromosomal abnormality. When this fetus
nuchal fold was scanned through a midline
approach the fold looked thick. However with an
oblique scan away from the midline it looked
normal. Explain
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Artefact 8 9
Though the appearance on the image is similar the
cause of the artefacts shown in Image A B are
different. In Image A the artefact is caused by
the presence of gas in the biliary tree. In Image
B the artefact is caused by the presence of
crystals in abnormal sinuses in the gall bladder
wall. Name the two different artefacts and
briefly discuss the formation of each.
Image A
Image B
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Artefact 10
In this coronal image the upper pole of the left
kidney is being imaged through the spleen but the
lower pole is not. Although only mild in this
case, explain what has caused the apparent
fractured appearance to the kidney.
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Ultrasound imaging identified a contour
abnormality and probable solid mass at the upper
pole of this left kidney (blue arrow). However
subsequent contrast enhanced CT scanning of the
abdomen revealed no abnormality here. What is the
cause of this pseudo-mass then?
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Another example of the same artefact.
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Artefact 11
A subtle but appreciable bend appears to have
occurred in the needle as it passes from
subcutaneous fat to breast tissue during this
FNAB. When the procedure was complete the needle
was examined carefully and appeared completely
straight. What is the explanation of this
appearance?
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Another example of Artefact 11
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Artefact 12
In abdominal ultrasound imaging the soft
tissue-air interface adjacent the diaphragm
almost invariably gives rise to apparent
liver-like tissue superior to the diaphragm on
the image. On occasions a there will be an
apparent double image of a specific structure,
such as the small haemangioma in Image A or the
Hepatic vein and IVC in Image B. With the aid of
a diagram explain the formation of these double
images.
Image A
Image B
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During this Paediatric Renal Ultrasound Scan a
cystic lesion (blue star) was transiently seen
deep to the urinary bladder. The lesion strangely
seemed to come and go as gas in the bowel deep to
the bladder peristalsed around. When the patient
emptied their bladder, careful scanning showed no
cyst in the pelvis. Give a explanation of this
imaging artefact.
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Artefact 13
Image A B are of the same section of the same
Achilles tendon. The only technical difference
between the two Images is a subtle change of scan
angle between images. The anechoic area (blue
arrow) in Image B is not real. Discuss the cause
of this artefact.
Image A
Image B
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The anechoic area (blue star) at the insertion of
this supraspinatus tendon is another example of
the artefact seen on the previous slide. This
artefact is very common in the supraspinatus
tendon because the tendon fibres curve over the
humeral head. Briefly explain how a sonographer
overcomes this in the practical setting.
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Equipment Artefacts
During this Early Pregnancy scan the transducer
was accidentally dropped. When scanning resumed a
vertically aligned anechoic band was seen in a
constant location down the left hand side of the
image. Explain these appearances.
Note appearance of active transducer wiped clean
with an isowipe
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Operator Artefacts
Both of the images below are not of diagnostic
quality. Explain why and what likely operator
errors have caused the artefact in each case.
Image A
Image B