Philips EPIQ 7 User Manual page 182

Transducers Acoustic Artifacts
thresholding that eliminates structures, and adjacent structure artifacts that add additional
information or hide structures. Editing artifacts result from data deleted from a rendered
image.
Color and Color Power Angio artifacts relating to gain may also be confusing in rendered
images. A color flash artifact can occur when the gain is set high and the transducer or patient
moves. When the gain is set too high, the color ROI box fills with color flash. When the gain is
set low, color bleed can occur. When the gain is set too low, insufficient color data renders the
image undiagnosable.
Color gain, directional, and motion artifacts can present themselves in 3D imaging. Color and
Color Power Angio gain artifacts are mainly related to the use of excessive gain resulting in
random color patterns in the 3D image that might be interpreted as diagnostically significant.
Directional artifacts are due to aliasing or directional confusion: The velocity range must be set
properly, and the relationship between the transducer orientation and the flow vector must be
understood. Patient motion can produce flash artifacts that are less obvious in 3D images than
in 2D imaging.
Dropout and shadowing are present in 3D imaging although they are more difficult to
recognize due to different and unfamiliar displays. Acoustic shadowing and other artifacts look
very different when displayed in 3D volumes and may be more difficult to recognize than on
standard 2D imaging. Those artifacts may produce apparent defects, such as limb abnormalities
or facial clefts, where they are not present. Acquiring data from multiple orientations may
avoid artifacts of this type.
Fetal limb deficit artifacts are specific to 3D volume images. Partially absent fetal limb bones
have been demonstrated. One explanation for the missing limbs was shadowing caused by
adjacent skeletal structures. Overcoming the limb deficit artifact can be accomplished by
changing the transducer position and the acquisition plane.
Motion artifacts in 3D volumes can be caused by patient motion, fetal movement, cardiac
motion, and movement of adjacent structures. Patient motion can produce flash artifacts that
are more obvious in 3D images than in 2D imaging.
Pseudoclefting and pseudonarrowing artifacts may be related to limb deficit artifacts. Artifacts
may be present in 3D imaging of the fetal face. Being aware of pseudoclefting of the fetal face
and pseudonarrowing of the fetal spine can help the sonographer understand and identify
these artifacts. As with 2D imaging, it is important to verify putative physical defects by using
additional images and other modalities.
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