Quality Assurance in Mammography

IMAGING & THERAPEUTIC TECHNOLOGY
Quality Assurance in
Mammography: Artifact
Analysis1
Jacquelyn P. Hogge, MD • Carolyn H. Palmer, RTR(M) • Caroline C.
Muller, RTR(M) • Sherrill T. Little, MD • Deborah C. Smith,
RTR(M) • Panos P. Fatouros, PhD • Ellen Shaw de Paredes, MD
Evaluation of mammograms for artifacts is essential for mammographic quality
assurance. A variety of mammographic artifacts (ie, variations in mammographic
density not caused by true attenuation differences) can occur and can create
pseudolesions or mask true abnormalities. Many artifacts are readily identified,
whereas others present a true diagnostic challenge. Factors that create artifacts
may be related to the processor (eg, static, dirt or excessive developer buildup
on the rollers, excessive roller pressure, damp film, scrapes and scratches, incomplete fixing, power failure, contaminated developer), the technologist (eg,
improper film handling and loading, improper use of the mammography unit
and related equipment, positioning and darkroom errors), the mammography
unit (eg, failure of the collimation mirror to rotate, grid inhomogeneity, failure
of the reciprocating grid to move, material in the tube housing, compression
failure, improper alignment of the compression paddle with the Bucky tray,
defective compression paddle), or the patient (eg, motion, superimposed objects or substances [jewelry, body parts, clothing, hair, implanted medical devices, foreign bodies, substances on the skin]). Familiarity with the broad
range of artifacts and the measures required to eliminate them is vital. Careful
attention to darkroom cleanliness, care in film handling, regularly scheduled
processor maintenance and chemical replenishment, daily quality assurance
activities, and careful attention to detail during patient positioning and mammography can reduce or eliminate most mammographic artifacts.
Abbreviations: ACR = American College of Radiology, QC = quality control
Index terms: Breast radiography, 00.112 • Breast radiography, quality assurance
RadioGraphics 1999; 19:503–522
1From
the Department of Radiology, Medical College of Virginia of Virginia Commonwealth University, 1101 E Marshall
St, Box 980615, Richmond, VA 23298 (J.P.H., C.P., C.M., S.T.L., P.F., E.S.D.); and the Department of Radiology, University
of Virginia Medical Center, Charlottesville, Va (D.S.). Recipient of a Certificate of Merit award for a scientific exhibit at
the 1997 RSNA scientific assembly. Received February 17, 1998; revision requested June 16 and received July 10; accepted July 14. Address reprint requests to J.P.H.
©RSNA,
1999
503
a.
Figure 1. Static artifact. This artifact may have a “ladybug”
(a) or dramatic lightning-like (b) appearance.
■
INTRODUCTION
Quality assurance refers to all systematic activities undertaken by the breast imaging staff
to ensure high-quality mammography. Quality
control (QC) more specifically refers to the technical aspects of mammography and is evaluated
with the 11 QC procedures outlined in the Mammography Quality Standards Act and performed
by the QC technologist (1,2). High-quality mammography demands a team approach involving
assessment of mammograms on a case-by-case
basis and immediate performance of repeat imaging when needed (3,4). Radiologists and mammographic technologists should be familiar with
the numerous artifacts that may create pseudolesions or mask true abnormalities. An artifact
is defined as any variation in mammographic
density not caused by true attenuation differences
in the breast (4). We have also included foreign
bodies and implanted medical devices in this
definition. Factors that create artifacts may be
related to the processor, the performance of
the examination by the technologist, the mammography unit, or the patient.
In this article, we review a variety of mammographic artifacts, identify their causes, and
discuss measures that can be taken to eliminate
a given artifact.
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PROCESSOR-RELATED ARTIFACTS
All facilities performing mammography are
now required to implement daily processor QC
to meet federal and American College of Radiology (ACR) criteria for accreditation (2). Processing conditions may vary widely from day to
day, which can result in a number of unwanted
artifacts if the processor components are not to
specifications or are improperly maintained.
Processor-related artifacts include static artifact, plus-density (black) or minus-density
(white) linear artifacts, water marks, scratches
and scrapes, film discoloration, and film mottling.
Static artifact may appear as a static “ladybug”
(Fig 1a) or as a dramatic lightning-like artifact
(Fig 1b) (5) and is more likely to occur in the
winter months when humidity is low. Other
causes of static include underreplenishment of
processor chemicals, improper film handling,
and improper electrical grounding of the processor. The ACR Mammography Quality Control
Manual recommends that darkroom humidity
be maintained between 40% and 60% year-round
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a.
b.
Figure 2. Processor-related plus-density (dark) linear artifacts include entrance roller marks (a) and
artifacts caused by inadequate film washing due to improper spring tension in the wash transporter
rack (b). Arrows indicate direction of film travel.
(2). Measures that can be taken to counteract
static include humidity control; installation of
static-reducing countertop materials in the darkroom; and use of static discharge systems, which
provide a continuous flow of ionized air to reduce static charge (2).
Processor-related linear artifacts are varied
and can be caused by a number of mechanisms.
An important first step is differentiation of such
linear artifacts from those related to the mammography unit. The ACR Mammography Quality Control Manual describes a simple test that
can be performed to determine the source of a
linear artifact. Two films are exposed with the
same technique and are then run perpendicular
to each other in the processor. Processor-related
linear artifacts will be parallel to each other on
the two films, whereas artifacts attributable to
the mammography unit or related equipment
will be perpendicular to each other (2,5). Several processor-related linear artifacts have been
identified. Entrance roller marks are wide plusdensity (dark) bands seen on the end of the film
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that first enters the processor (Fig 2a). Dirt on
the rollers can produce minus-density linear artifacts parallel to the direction of film travel (6),
whereas excess build-up of developer on the
rollers may cause plus-density lines (1). Improper
spring tension in the wash transporter rack
may also cause plus-density linear artifacts due
to inadequate washing of processor chemicals
from the film (Fig 2b). Excessive roller pressure
may produce linear artifacts perpendicular to
the direction of film travel (6). Adequate processor cleaning and chemical replenishment
along with proper mechanical adjustment of
the processor should prevent or eliminate this
type of artifact.
Wet roller or surface drying marks (Fig 3)
may be caused by worn and uneven or erratically rotating rollers, underreplenishment of
processor chemicals, improperly low fixer temperature, improperly high dryer temperature, or
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a.
Figure 4.
b.
Water spots with clumping of silver halide granules (arrow).
ineffective exit squeegee rollers. Poor dryer ventilation, excessively low dryer or fixer temperature, or depleted levels of fixer solution may
cause damp films. Clumping of silver halide
granules can occur if the dryer is too hot and
water droplets form during the drying process
(Fig 4). It is recommended that the dryer temperature be set as low as possible while still
producing films that are sufficiently dry when
they exit the processor (7).
Scrapes and scratches create artifacts that are
readily identified and can be caused by a number
of factors including dirty or worn rollers (Fig 5),
incorrect tension on the drive chains, improperly
positioned crossover rollers, misaligned guide
shoes (Fig 6) (5), improper alignment of the film
on the feed tray, improperly mixed processor
chemicals, or a deficient replenishment rate.
Incomplete fixing causes fading and brownish discoloration of films (Fig 7). This problem
may be caused by loss of circulation in the fixer
tank, underreplenished or improperly mixed
fixer, or low fixer temperature.
A power failure that occurs during processing
results in interruption of film travel through the
processor. Artifact is produced by prolonged contact between the film and the developer chemicals, which causes overdevelopment and dark-
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Figure 3. Wet roller or surface drying marks.
This wide, irregular and blotchy linear artifact
(arrowheads) may be due to a variety of causes
(arrow indicates direction of film travel).
ening of the affected area of the film. Additional
linear artifacts are caused by excessive pressure
on the film from the transport rollers (Fig 8).
Contaminated developer produces decreased
contrast, film mottle, and plus-density linear artifacts (Fig 9). Such contamination most often
occurs when the crossover rollers are removed,
cleaned, and replaced without simultaneous replenishment of the processor chemicals. The
developer chemicals should be replenished
whenever the crossover rollers are cleaned (8).
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6.
Figures 5, 6. (5) Severe emulsion “pick-off” artifact caused by dirty rollers. (6) Scratches (black arrows) caused by misaligned guide shoes (white arrow indicates direction of film travel).
Figures 7–9. (7) Fading and brownish discoloration caused by improper developer fixation.
(8) Plus-density linear artifacts resulting from power failure. (9) Plus-density linear artifacts and film
mottle caused by contaminated developer.
9.
7.
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8.
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a.
Figure 10.
b.
Fingerprints left prior to exposure (arrows in a) and after exposure (b).
TECHNOLOGIST-RELATED ARTIFACTS
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Artifacts associated with performance of the
examination by the technologist include improper film handling or loading, inadequate
screen cleaning procedures, errors in use of
the mammography unit and related equipment,
and positioning and darkroom errors. Grease,
food, lotions, and other substances on the hands
will cause artifacts when the mammographic
film is handled prior to processing. Fingerprints
left before exposure will be minus density (white)
(Fig 10a), whereas fingerprints left after exposure will be plus density (black) (Fig 10b) (5).
Washing the hands prior to film handling and
prohibiting food and beverages in the darkroom
help prevent fingerprint artifacts. Pressure artifacts can be caused by touching the film with
the fingernails or fingertips or by improperly
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storing film boxes lying flat rather than standing on end. Fingernail marks are seen as plusdensity or dark curvilinear artifacts. Fingertip
pressure artifacts appear as minus-density oval
artifacts that may be mistaken for a neodensity
or a nodular density if seen on only one view
(Fig 11). Neither artifact should be present on a
repeat image. Improper storage of film boxes
may cause a minus-density artifact in the same
location on all films from the same box (Fig 12).
In such a case, repeat images should be obtained
with film from a different box and the box containing the films on which the artifact appears
should be discarded.
Poor screen-film contact can be due to a number of causes including air trapped between
the film and the intensifying screen, improper
seating of the film in the cassette, lint, hair, dust,
a warped cassette frame, damage to the cassette
latches, or a dented intensifying screen (1,4).
Poor screen-film contact should be differentiated
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a.
b.
Figure 11. Fingertip pressure artifact. (a) Craniocaudal mammogram of the medial left breast shows
an ill-defined, oval nodular density in the subcutaneous tissues (arrow). The artifact was seen only on
this view; spot compression mammograms of this area (not shown) were negative. (b) Repeat craniocaudal mammogram of the left breast shows no abnormality.
from image blur due to motion or inadequate
compression. Screen-film contact testing is performed initially for new screens, then semiannually and whenever persistent reduced image
sharpness is detected. A copper mesh (40 wires
per inch) is used to test screen-film contact as
specified in the ACR Mammography Quality Control Manual. Five or less small (<1 cm) areas of
poor contact are acceptable. Areas of poor
screen-film contact larger than 1 cm that are
not eliminated by repeat cleaning are unacceptable, and the cassette should be discarded (2).
The most common cause of poor screen-film
contact is air trapped between the film and the
cassette when the film is loaded (6). The ACR
Mammography Quality Control Manual recommends that cassettes be allowed to sit for at least
15 minutes after loading to allow trapped air to
dissipate (2). If the cassette is used too quickly
after loading, trapped air may cause a focal area
of image blur (Fig 13a). This 15-minute waiting
Figure 12. Pressure artifacts caused by improper
film storage. Curvilinear minus-density artifacts (arrows) appeared in the same location on every film
from the same box.
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a.
c.
Figure 13. Poor screen-film contact caused by air trapped between the film and the intensifying screen (arrows in a), improper
seating of the film in the cassette (arrowheads in b), and lint (c).
period necessitates that most facilities have at
least eight cassettes of each size. If the film is
not properly seated in the cassette along one
edge, a rectangular area of poor screen-film contact will occur (Fig 13b). Lint (Fig 13c), dust,
and hair usually cause readily identifiable artifacts with a surrounding area of poor screen-film
contact. Occasionally, however, dust or fingernail polish will cause indistinct artifacts that simulate microcalcifications (Fig 14) (3). Because all
cassettes are required to have a unique radiopaque identification number, an artifact caused
by dust or other material on the intensifying
screen may be recognized by noting its recurrence in the same location on films used in the
same cassette. If an artifact is suspected, the
mammographic view on which the finding is
identified should be repeated with a different
cassette. Daily darkroom cleaning and weekly
cleaning of mammographic intensifying screens
are both intended to reduce artifacts caused by
debris or dust in the cassettes (2). In addition,
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b.
many facilities restrict the use of fingernail polish and hand lotions by their mammographic
technologists.
Improper loading of films or the cassette into
the mammography unit are common causes of
unacceptable mammograms. Because mammographic film is single emulsion, the emulsion
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Figure 14. Artifacts
caused by dirty screens.
(a) Minus-density linear
artifact caused by fingernail polish on the intensifying screen. (b) Dust
artifact simulating microcalcifications (arrows).
a.
b.
a.
b.
Figure 15. Underexposure caused by improper loading of film into the cassette. The films in a and b
were exposed with the same technique (112 mAs, 25 kVp); however, the film in a was correctly loaded
with the emulsion side in contact with the intensifying screen, whereas the film in b was incorrectly
loaded and is underexposed.
on the film must be in contact with the intensifying screen for a properly exposed image. If
the film is loaded into the cassette upside down
so that the emulsion is not in contact with the
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intensifying screen, the resultant image will be
underexposed (Fig 15). Accidental loading of
two films into the same cassette will result in a
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16.
17.
18.
Figures 16–18. (16) Grossly underexposed silhouette of the breast caused by accidental
loading of two films into the cassette. (17) Artifact caused by improperly loaded film. The
film became folded upon itself when it was loaded, resulting in a nonexposed area (“cutoff”), poor screen-film contact, and a linear crease. (18) Artifact caused by improperly
loaded film. An irregular light leak (arrows) was produced when the edge of the film was
closed in the cassette hinge during loading.
grossly underexposed silhouette of the breast
(Fig 16). A film that becomes folded upon itself
inside the cassette during loading will have an
underexposed area with a large linear crease
artifact and an adjacent area of poor screen-film
contact (Fig 17). Closure of the film bin door on
a film can also produce crease marks. Films that
have an edge caught in the hinge of the cassette
may have irregularly spaced, ill-defined black
marks at the edge due to light leak (Fig 18).
Errors that occur during the weekly cleaning
of intensifying screens and produce artifacts include loading films too soon after the cleaning
solution is used and failing to use lint-free materials. Films that are loaded too soon after the
screens are cleaned may be covered with a bizarre artifact caused by the removal or clumping of silver halide granules, which form clusters of black specks and white pick-off artifacts
where they have been washed off (Fig 19) (5).
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Figure 19. Artifact caused by improper loading of
film into a cassette that was still damp from cleaning. Bizarre clumping of silver halide granules and
corresponding areas of white pick-off artifact are
seen (arrows).
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20a.
20b.
21.
Figures 20, 21. (20) Artifact resulting from failure to use a grid. The film in a was exposed with
use of a proper grid, whereas the film in b was exposed without the grid in place. Note the degradation
of contrast due to increased scatter in b. (21) Double exposure. This error requires that both images
be repeated. Many of the new mammography units have built-in safeguard mechanisms to prevent
such an error.
recommends cassettes be allowed to air dry for
30 minutes after being cleaned with an acceptable screen cleaning solution (2). Failure to use
lint-free materials may create more minus-density
or pick-off artifacts than were present prior to
cleaning (Fig 14).
Improper operation of the mammography
unit includes failure to use the grid, failure to
change the cassette between exposures, and
improper loading of the cassette into the Bucky
tray. Failure to replace the grid may occur after
a magnification view has been obtained because
an air gap technique rather than a grid is used
to reduce scatter in magnification imaging. Failure to use the grid will result in overall graying
of the mammogram and degradation of image
contrast secondary to increased scatter on the
film (Fig 20) (3). This artifact can be differentiated from poor image contrast due to improper
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processor chemical maintenance in that it represents a sudden change from mammographic
findings seen earlier the same day. Failure to
change the cassette between exposures will result in double exposure (ie, superimposition of
two images) and necessitates that both views
be repeated (Fig 21). Some of the newer mammography units have built-in safeguard mechanisms to prevent double exposure. The cassette
can be improperly loaded into the Bucky tray
of the mammography unit either upside down,
in which case the internal structure of the cassette will appear on the mammogram (Fig 22),
or front-back reversed, in which case the identification flash will appear over a portion of the
breast tissue (Fig 23). Both errors necessitate
repeat imaging.
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22.
23.
Figures 22, 23. (22) Artifact caused by improper (upside-down) loading of the cassette into the
Bucky tray. The internal structure of the cassette is superimposed on the image. (23) Artifact caused
by improper (front-back reversed) loading of the cassette into the Bucky tray. The identification flash
is superimposed over breast tissue.
Figure 24. Artifact caused by running films too
close together through the processor. The two
films were ruined when they became completely
overlapped and stuck together.
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Figure 25. Film fog artifact (arrows) caused
when the technologist briefly turned on the
darkroom overhead light before the film had
entered the processor completely.
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27.
28.
29.
Figures 26–29. (26) Light leak artifact (arrow) caused by a cracked cassette frame. (27) Unusual
light leak artifact (arrows) caused by the cassette being incompletely latched before it was brought
out of the darkroom. (28) Film fog artifact (arrows) on a test strip caused by fluorescent fingernail
polish worn by the technologist. (29) Film fog artifact caused by a fluorescent bandage worn by the
technologist. Note the word “RAD” exposed on the phantom image.
Other technologist-related artifacts include
those caused by running films too close together
through the processor and by film fog. Running
films too close together may cause them to
overlap and stick together, potentially ruining
both films (Fig 24). Film fog will occur if the
film is exposed prematurely (ie, before being
processed). It may also occur if there is a light
leak in the darkroom, an improper safelight is
used, the safelight filter is cracked, improper
processor indicator lights are installed, the film
is stored at too high a temperature, the film bin
is accidentally exposed to light, or the darkroom
overhead light is turned on before the film enters
the processor completely (Fig 25). The safelight
housing and filter should be inspected for any
defects, and only the recommended wattage
should be used. Use of a safelight with higher
wattage than that recommended for the filter
may cause more rapid fading of the safelight fil-
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ter and subsequent film fog (5). The darkroom
should be inspected for structural light leaks,
which commonly occur at the door, in the ceiling, at fixtures, and around through-the-wall
processors. The Mammography Quality Standards Act QC test for film fog is performed initially, semiannually, and whenever bulbs or filters are changed or excessive fog is suspected
(2). Light leaks, which are a variation of film
fog, may result if the edge of the film is caught
in the hinge of the cassette (Fig 16), the cassette
is cracked or broken (Fig 26), or the cassette is
not securely latched before being brought out
of the darkroom (Fig 27). Unusual causes of film
fog include fluorescent T-shirts, fingernail polish (Fig 28), and bandages worn by the technologist during film handling (Fig 29).
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ARTIFACTS RELATED TO THE MAMMOGRAPHY UNIT
■
Artifacts related to the mammography unit usually necessitate a service call to repair the malfunctioning component. Such artifacts may be
caused by failure of the collimation mirror to
rotate out of the field of view during exposure,
grid inhomogeneity, failure of the reciprocating
grid to move, material that has fallen down into
the tube housing, compression failure, improper
alignment of the compression paddle with the
Bucky tray, and a defective compression paddle.
Failure of the collimation or illumination mirror
to rotate out of the x-ray beam during exposure
produces a large, well-circumscribed oval artifact on the mammogram (Fig 30). The shape and
intensity of this artifact vary with the mammography unit being used. Material that has fallen inside the tube housing will create a recurrent
minus-density artifact that can be differentiated
from pick-off artifact (caused by a dirty cassette
screen) by noting that it occurs in the same location on multiple cassettes and has indistinct
margins. Such an artifact will appear indistinct
due to magnification and geometric blurring
caused by the gap between the tube housing
and the mammographic film.
Grid lines were sometimes seen on the images
produced with the stationary grids used on older
mammography units. However, stationary grids
are no longer recommended for use in mammography; current mammography units make
use of reciprocating grids, so that grid lines are
not seen unless the grid fails to move and produces inhomogeneous white and black lines
(Fig 31). In such cases, repeat imaging is mandatory because calcifications may be either simulated or obscured. An unusually long or short
exposure or an improper Bucky timing rate will
produce faint grid lines (Fig 32). Recurrence of
these lines necessitates a service call to adjust
the rate at which the Bucky tray moves. Grid
inhomogeneity may be detected on phantom
images and may be due to warping of the grid.
Improperly aligned compression devices may
result in linear or rectangular cutoff due to superimposition of the posterior lip of the compression paddle on the mammogram (Fig 33). A
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Figure 30. Large, well-circumscribed oval artifact
resulting from failure of the collimation mirror to rotate
out of the path of the x-ray beam during exposure.
similar artifact can be caused by a compression
paddle that is too thin and bends under compression (4). The compression paddle and the
image receptor should be the same size, and
the compression paddle should remain parallel
to the image receptor during compression, with
the posterior lip of the compression paddle just
behind the posterior edge of the image receptor.
The posterior lip of the compression paddle
should be straight rather than curved, and its
vertical component should be high enough to
prevent the overlapping of skin or other body
parts on the image (2,4). Failure to maintain compression for the duration of the exposure results
in image blur due to both motion and inadequate
compression.
■
PATIENT-RELATED ARTIFACTS
Patient-related artifacts may be caused by motion
or by superimposition of objects or substances
such as body parts, jewelry, clothing, hair, implanted medical devices, foreign bodies, or substances on the skin. Many deodorants (Fig 34),
powders (Fig 35), ointments (Fig 36), and lotions
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32.
Figures 31, 32. (31) Inhomogeneous white and black lines owing to failure of the reciprocating
grid to move. (32) Faint regular grid lines caused by an unusually short exposure.
Figure 33. Artifact caused by
an improperly aligned compression paddle. Improper alignment
of the compression paddle with
the Bucky tray causes the posterior lip of the paddle to be superimposed on the mammogram,
creating a linear area of cutoff (arrows). This situation may also be
caused by a compression paddle
that is either broken or too flexible, and bends with compression.
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Figure 34.
Deodorant artifact (arrows).
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35.
Figures 35, 36. (35) Powder artifacts. The patient presented
with new bilateral “calcification clusters” for which she had
been encouraged to undergo biopsy at another institution, although no magnification views had been obtained. On magnification views obtained at our institution, the “calcifications” proved
to be powder artifacts (arrows). (36) Artifact caused by ointment (arrows).
contain radiopaque components such as zinc,
aluminum, and magnesium, which may simulate
calcifications at mammography. Many facilities
request that women not wear deodorant or powders on the day of their examination to reduce
the occurrence of artifacts. Pharmaceutical skin
patches such as nicotine or estrogen patches may
create a pseudomass (3) consisting of a poorly
defined area of opacity, usually on the mediolateral
oblique projection. Such an artifact can be more
easily identified when bubbles of air are trapped
under the patch (Fig 37). The mammographic
technologist is responsible for examining the
patient prior to mammography and removing
any pharmaceutical patches that will appear in
the field of view.
Motion artifact is usually due to patient motion during mammography and is more frequently
seen on the mediolateral oblique projection because the breast is not supported by the Bucky
tray as it is for craniocaudal views (Fig 38). Recurrent motion artifact in multiple patients may
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36.
indicate that the compression mechanism is
not functioning properly. Motion artifact may
also result if the cassette drops slightly during a
mediolateral or mediolateral oblique exposure.
Mammograms with motion artifact must be repeated because calcifications will be obscured
(3,8). Motion artifact should be distinguished
from poor screen-film contact and from image
blur due to poor compression, which is most
commonly seen anteriorly in patients with large
or thick breasts. An additional anterior compression view should be obtained to complete the
study in such cases (5).
Most artifacts caused by superimposed objects
are readily identified and are easily corrected
by repeating the exposure after first making sure
that the overlapping object is safely out of the
path of the x-ray beam. Such objects may include
the opposite breast (Fig 39), shoulder, chin, nose
(Fig 40), earlobe, fingers (Fig 41), adipose tissue,
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39.
40.
41.
Figures 39–41. (39) Artifact caused by superimposition of the patient’s opposite breast and clothing.
(40) Artifact caused by superimposition of the patient’s nose. (41) Artifact caused by superimposition of
the patient’s fingers.
Figure 37. Artifact caused by a pharmaceutical
patch (arrowheads). Note the bubble of air trapped
under the patch.
Figure 38. Severe motion artifact. Repeat mammography was performed because calcifications
and masses would have been obscured.
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a.
Figure 42. Hair artifact. (a) Curvilinear white
lines (arrowheads). (b) Tiny minus-density artifacts (arrowheads) simulating microcalcifications posteriorly on craniocaudal mammograms.
The tip of a hair braid was responsible for this
artifact.
b.
43.
44.
Figures 43, 44. (43) Artifact caused by clothing (arrowheads) simulates a ruptured saline breast
implant. (44) Artifact caused by a pacemaker.
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45.
46.
Figures 45, 46. (45) Artifact caused by a retained Dacron cuff from a Hickman catheter (marked with a metallic BB). The patient presented with a palpable lump that represented the cuff from a previously removed
catheter. (46) Artifact caused by bilateral axillary-femoral grafts.
Dacron cuffs from Hickman catheters (Fig 45)
(9,10), and vascular grafts (Fig 46). Large implanted devices such as pacemakers prevent
adequate visualization and compression of adjacent breast tissue, usually in the axillary tail on
the mediolateral oblique view. Foreign bodies
that may cause artifacts include calcified suture
material, fishhooks (Fig 47), transected wires
from previous needle localization procedures
(11), metallic clips or coils from stereotactic biopsy or embolization procedures (12–14), surgical sponges (15), residual silicone from previous implant rupture (Fig 48), or bullets or metallic fragments from gunshot wounds (Fig 49).
Tattoos are usually not visible mammographically, although lymphatic intravasation of the
dye used for tattooing may occasionally be
seen (Fig 50).
Figure 47.
Artifact caused by a fishhook.
■
jewelry, or glasses. Extremely kyphotic patients, patients with paralysis, and uncooperative patients may present positioning challenges.
Artifact from hair may be seen as large, curvilinear white lines (Fig 42a) or may simulate calcifications and be more difficult to recognize
(Fig 42b). Hair artifact, which is usually seen on
the craniocaudal projection, is largely prevented
on current mammography units with use of extended face shields. Artifacts caused by clothing or examination gowns are also usually readily
identified and corrected but may simulate a ruptured saline breast implant (Fig 43). Implanted
pacemakers (Fig 44), catheters, automatic implantable cardioverter-defibrillators, retained
March-April 1999
CONCLUSIONS
Many artifacts are easily identified and do not
present a diagnostic challenge. Other artifacts
may create pseudolesions or mask true abnormalities. Radiologists and technologists should
be familiar with the broad range of artifacts and
the measures required to eliminate them. Careful attention to darkroom cleanliness, care in
film handling, regularly scheduled processor
maintenance and chemical replenishment, daily
quality assurance activities, and careful attention to detail during patient positioning and performance of mammography can reduce or eliminate most mammographic artifacts.
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48.
49.
50.
Figures 48–50. (48) Artifact caused by residual silicone from previous implant rupture (arrow). (49) Artifact caused by metallic fragments from a gunshot wound (arrows). (50) Artifact caused by lymphatic intravasation of dye used in creating a tattoo (arrows). The tattoo itself was not visible mammographically.
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Volume 19
Number 2