Cameron
F. Roberts,
MD
Intraorbital Mimicking
J. Leehey
Paul
#{149}
III, MD
Wood Foreign Air at CT’
Body
Computed tomography (CT) revealed a 2-cm linear area of extremely low attenuation in the left orbit of a boy who had been poked in the eye with a tree branch. The appearance and attenuation of the area suggested air, so a diagnosis of orbital emphysema was mitially considered. Further research indicated that wood mimicks the CT attenuation and appearance of air. A wood splinter was surgically removed from the orbit. Index terms: abnormalities, Radiology
T
Foreign bodies, 22.461, 22.462 1992;
22.461
#{149} Orbit,
185:507-508
of wood foreign objects at computed tomography (CT) varies according to type of wood, whether it is fresh or dry, the degree of hydration as influenced by adjacent inHE appearance
flammation,
types which icked
and
the
presence
of
some
of paint. We describe a case in a wooden foreign body mimthe appearance of air at CT. CASE
REPORT
11-year-old boy was “poked in the left eye” by a tree branch while running. His local physician removed two wooden foreign bodies from beneath the left upper eyelid and then referred him for ophthalmologic evaluation. ExAn
amination
by
the
ophthalmologist
showed minimal mueosal laceration on the margin of the left upper eyelid, a diagonal corneal abrasion, and a eonjunctival laceration superotemporalby. No foreign bodies were evident at visual inspection or palpation, and ocular motility was normal. The patient was treated
with
administered follow-up there was
an
eye
steroids examination a questionable
patch
and
topically
and antibiotics. the next day, indentation
At
of
Coronal CT image shows a linear object (arrowheads) of low attenuation (-252 FlU) in the upper outer quadrant of the left orbit.
the left globe, suggesting the possibility of a residual foreign body. For this reason, a CT scan was ordered. Axial and coronal 1.5-mm scans were obtained through the orbits with a 9800 unit (GE Medical Systems, Milwaukee). These revealed a linear 2-cm area of extremely low attenuation (Figure) in the upper temporal aspect of the left orbit, just outside the globe, and two adjacent bubbles of air (images not shown). Several standard textbooks were eonsuIted to help identify what this linear low-attenuating object represented (1-3).
The
sema.
sen
From the Department Clinic
Ltd.
of Radiology,
Gundersen-Lutheran
GunderMedical
Center, 1836 South Aye, La Crosse, WI 54601. Received March 12, 1992; revision requested April 15; revision received June 15; accepted June 24. Address reprint requests to C.F.R. C
RSNA,
1992
did
not
mention
Further
research
into
the
litera-
ture, however, showed case reports of wood mimicking the appearance of air, and the ophthalmologist was then notifled that the indentation probably represented a wood splinter. A splinter was subsequently
1
references
that a wood foreign object could have attenuation similar to that of air, and the area of low attenuation was initially considered to represent orbital emphy-
removed
with
the
patient
under general anesthesia. The foreign body broke during surgery. The total length of the two fragments was estimated as 2.5-3.0 cm. This correlated well with the size of the area of attenuation at CT, which might not have displayed the entire length of the foreign body. The patient recovered without complication.
DISCUSSION In our
patient,
was
initially
error
that
Myilyla
Jooma linear
the wood
foreign
misinterpreted
has also been
reported
et al (4), Green
an
by
et al (5), and
et ab (6). We finally “gas”
body
as air,
attenuation
decided was
the
a foreign
body because of its linear configuration, which did not conform to that of an anatomic structure, and on the basis of an article that described a wood foreign body in the forearm as having the appearanee of air (7). Kadir et al (8) soaked various types of wood for 24 hours in water and found CT attenuation ranging from -276 to +27
HU).
EM!
units (-552 (undefined
attenuation
“Heavy”
woods
to +54 in
their paper) showed substantially higher attenuation than that of water, whereas “light” woods, plywood, and particle board showed attenuation simibar to or lower than that of water and sometimes approximated that of air. They speculated that the bow attenuation was due to trapped air, which we presume is the reason for the appearanee
of the
foreign
body
Glatt et ab (9) found balsa, plywood, pine, were hypoattenuating HU).
After
3 days
in our
of immersion
ter, plywood became but the CT appearance
patient.
that dry pieces cedar, and oak (-984 to -356
of
in Wa-
hyperattenuating, of balsa, pine, n#{149},
cedar, and oak was unaffected. Fresh branches of pine, cedar, and walnut were hypoattenuating, with occasional hyperattenuating rings. The CT appearance of a pencil was not different after the surface of paint was shaved off the pencil.
In
their
model,
a wide
ography, CT, and US are negative in a patient with high suspicion for a nonmetaffie intraorbital foreign body. Once a wooden foreign body is diagnosed, Grove (14) advocates culturing a specimen of the wound or foreign body for bacteria and administering systemic antibiotics, then removing foreign objects composed of vegetable matter because of the likelihood that they will lead to abscess formation. If an abscess and fistula form, the fistula tract can be
window
width (up to 1,000 HU) was important in the detection of wood. Because of volume averaging, measurement of absorption coefficients was not useful in distinguishing
small
pieces
of
wood
from air bubbles. Hansen et ab (10) studied twigs of oak, pine, wax myrtle, dogwood, and cedar, both dry and soaked in water for 60 hours. The attenuation of dry wood ranged from -461 Wi (pine) to -88 HU (oak). All woods became more highly attenuating after soaking. Weisman et ab (11) reported a hyperattenuating
wood
intraorbital
foreign
body that caused a temporal lobe abseess. They attributed the hyperattenualion to the coating of paint found on the foreign body. Lindahl (12) also reported a wood foreign body that was hyperattenuating,
which
was
attributed
rounding inflammation mation. The choice of imaging uation
of intraorbital
and
to sur-
abscess
fractures
recommends
cnQ
.
studies foreign
abscesses.
MR imaging
ology
extruded
nated
the
Wood
is often
Clostridium
immunization
tetani,
should
be
infallible
(16,17).
9.
in evab-
bodies
10.
problems
such
Green
et al (5)
if plain
radi-
Weinstein
MA,
Berlin
wood
11.
MT.
2.
Latehaw
RE, ed.
of the head, 3.
4.
as 5.
Computed
neck and spine.
Chicago: eds.
Year
12.
13.
Green
BF, Kraft
traorbital wood: onanee imaging. 608-611.
SF, Carter
KD, et al.
clinical
15.
Ossoinig
Arch Otolaryngol
KC. (letter).
L, Schatz in penetratretained for-
1983; 109:
tomography Aeta Radiol
of in1987;
Detection of wood foreign Ophthalmology 1991; 98:
Grove SG Jr. Orbital trauma. In: Spaeth G, ed. Ophthalmic surgery: principles and practice. 2nd ed. Philadelphia: Saunders, 1990; 496-497. Wesley RE, Wahl
JW, LodenJP,
Management
ies in the orbit. 932.
17.
RC,
intracranial
PJ, Schut
265-268. Lindahl S. Computed traorbital foreign bodies. 28:235-240.
RR.
16.
Plast
limitations of comJ Neurosurg 1988;
tomography.
68:752-756. Weisman RA, Savino
bodies 274.
Cranial
computed tomography. St Louis: Mosby, 1985; 569-573. Myllyla V, Pyhtinen J, Paivansalo M, Tervonen 0, Koskeba P. CT detection and location of intraorbital foreign bodies: experiments with wood and glass. ROFO 1987; 146:639-643.
Ophthalm
Penetrating
wounds:
eign bodies.
tomography
Book Medical, 1985; 369. Williams AL, Haughton VM,
orbit.
NJ. Computed tomography ing wounds of the orbit with
Berlin
LA. Orbits. In: Haaga JR. Alfidi RJ, eds. Computed tomography of the whole body. St Louis: Mosby, 1983; 309.
in the
RA.
puterized
knowledge
AJ, Modic
bodies
Reconstr Surg 1990; 6:108-114. Hansen JE, Gudeman 5K, Holgate
so tetanus
14. 1.
computerized tomography in the detection of intraorbital foreign bodies. Computerized Tomogr 1977; 1:151-156. Glatt HJ, Custer PL, Barrett L, Sartor K. Magnetic resonance imaging and computed tomography in a model of wooden
Saunders
that wood has variable appearances and can mimic air at CT will increase the accuracy of diagnosis. U
is
Neurol 1984; 21:236-238. Bodne D, Quinn SF, Cochran CF. Imaging foreign glass and wooden bodies of the extremities with CT and MR. J Comput Assist Tomogr 1988; 12:608-611. Kadir 5, Aronow 5, David KR. The use of
contami-
established
The
Jooma R, Bradshaw JR, Coakham HB. Computed tomography in penetrating eranial injury by a wooden foreign body. Surg
foreign
(10). The use of thin-section two-plane (axial and coronal) CT and variable window widths is extremely useful in deteetion of wood foreign bodies and associated injuries and complications, but is not
8.
foreign
Sometimes, retained bodies are spontaneously
(15).
with
and
7.
References
of associated and
followed
removed. foreign
for-
controversial. Ossoinig (13) suggested standardized ophthalmic ultrasonography (US) (combined use of standardized A-sean and B-scan) should be used first, while Hansen et al (10) recommended CT as “the single most effective test and should be the primary diagnostic examination in suspected penetrating orbital and cranial wounds.” CT also allows detection
surgically
body wood
6.
of wooden South
Med
J
Tate E, Cupples H. Detection foreign bodies with computed
Henderson
foreign 1982;
bod-
75:924-
of orbital tomogra-
phy: current limits. AJR 1981; 137:493-495. Woolfson JM, Wesley RE. Magnetic reso-
nance imaging and computed tomographic scanning of fresh (green) wood foreign bodies in dog orbits. Ophthalmic Plast Reeonstr
Surg
1990;
6:237-240.
In-
detection by magnetic resOphthalmology 1990; 97:
November
1992
F. Roberts,
MD
Intraorbital Mimicking
J. Leehey
Paul
#{149}
III, MD
Wood Foreign Air at CT’
Body
Computed tomography (CT) revealed a 2-cm linear area of extremely low attenuation in the left orbit of a boy who had been poked in the eye with a tree branch. The appearance and attenuation of the area suggested air, so a diagnosis of orbital emphysema was mitially considered. Further research indicated that wood mimicks the CT attenuation and appearance of air. A wood splinter was surgically removed from the orbit. Index terms: abnormalities, Radiology
T
Foreign bodies, 22.461, 22.462 1992;
22.461
#{149} Orbit,
185:507-508
of wood foreign objects at computed tomography (CT) varies according to type of wood, whether it is fresh or dry, the degree of hydration as influenced by adjacent inHE appearance
flammation,
types which icked
and
the
presence
of
some
of paint. We describe a case in a wooden foreign body mimthe appearance of air at CT. CASE
REPORT
11-year-old boy was “poked in the left eye” by a tree branch while running. His local physician removed two wooden foreign bodies from beneath the left upper eyelid and then referred him for ophthalmologic evaluation. ExAn
amination
by
the
ophthalmologist
showed minimal mueosal laceration on the margin of the left upper eyelid, a diagonal corneal abrasion, and a eonjunctival laceration superotemporalby. No foreign bodies were evident at visual inspection or palpation, and ocular motility was normal. The patient was treated
with
administered follow-up there was
an
eye
steroids examination a questionable
patch
and
topically
and antibiotics. the next day, indentation
At
of
Coronal CT image shows a linear object (arrowheads) of low attenuation (-252 FlU) in the upper outer quadrant of the left orbit.
the left globe, suggesting the possibility of a residual foreign body. For this reason, a CT scan was ordered. Axial and coronal 1.5-mm scans were obtained through the orbits with a 9800 unit (GE Medical Systems, Milwaukee). These revealed a linear 2-cm area of extremely low attenuation (Figure) in the upper temporal aspect of the left orbit, just outside the globe, and two adjacent bubbles of air (images not shown). Several standard textbooks were eonsuIted to help identify what this linear low-attenuating object represented (1-3).
The
sema.
sen
From the Department Clinic
Ltd.
of Radiology,
Gundersen-Lutheran
GunderMedical
Center, 1836 South Aye, La Crosse, WI 54601. Received March 12, 1992; revision requested April 15; revision received June 15; accepted June 24. Address reprint requests to C.F.R. C
RSNA,
1992
did
not
mention
Further
research
into
the
litera-
ture, however, showed case reports of wood mimicking the appearance of air, and the ophthalmologist was then notifled that the indentation probably represented a wood splinter. A splinter was subsequently
1
references
that a wood foreign object could have attenuation similar to that of air, and the area of low attenuation was initially considered to represent orbital emphy-
removed
with
the
patient
under general anesthesia. The foreign body broke during surgery. The total length of the two fragments was estimated as 2.5-3.0 cm. This correlated well with the size of the area of attenuation at CT, which might not have displayed the entire length of the foreign body. The patient recovered without complication.
DISCUSSION In our
patient,
was
initially
error
that
Myilyla
Jooma linear
the wood
foreign
misinterpreted
has also been
reported
et al (4), Green
an
by
et al (5), and
et ab (6). We finally “gas”
body
as air,
attenuation
decided was
the
a foreign
body because of its linear configuration, which did not conform to that of an anatomic structure, and on the basis of an article that described a wood foreign body in the forearm as having the appearanee of air (7). Kadir et al (8) soaked various types of wood for 24 hours in water and found CT attenuation ranging from -276 to +27
HU).
EM!
units (-552 (undefined
attenuation
“Heavy”
woods
to +54 in
their paper) showed substantially higher attenuation than that of water, whereas “light” woods, plywood, and particle board showed attenuation simibar to or lower than that of water and sometimes approximated that of air. They speculated that the bow attenuation was due to trapped air, which we presume is the reason for the appearanee
of the
foreign
body
Glatt et ab (9) found balsa, plywood, pine, were hypoattenuating HU).
After
3 days
in our
of immersion
ter, plywood became but the CT appearance
patient.
that dry pieces cedar, and oak (-984 to -356
of
in Wa-
hyperattenuating, of balsa, pine, n#{149},
cedar, and oak was unaffected. Fresh branches of pine, cedar, and walnut were hypoattenuating, with occasional hyperattenuating rings. The CT appearance of a pencil was not different after the surface of paint was shaved off the pencil.
In
their
model,
a wide
ography, CT, and US are negative in a patient with high suspicion for a nonmetaffie intraorbital foreign body. Once a wooden foreign body is diagnosed, Grove (14) advocates culturing a specimen of the wound or foreign body for bacteria and administering systemic antibiotics, then removing foreign objects composed of vegetable matter because of the likelihood that they will lead to abscess formation. If an abscess and fistula form, the fistula tract can be
window
width (up to 1,000 HU) was important in the detection of wood. Because of volume averaging, measurement of absorption coefficients was not useful in distinguishing
small
pieces
of
wood
from air bubbles. Hansen et ab (10) studied twigs of oak, pine, wax myrtle, dogwood, and cedar, both dry and soaked in water for 60 hours. The attenuation of dry wood ranged from -461 Wi (pine) to -88 HU (oak). All woods became more highly attenuating after soaking. Weisman et ab (11) reported a hyperattenuating
wood
intraorbital
foreign
body that caused a temporal lobe abseess. They attributed the hyperattenualion to the coating of paint found on the foreign body. Lindahl (12) also reported a wood foreign body that was hyperattenuating,
which
was
attributed
rounding inflammation mation. The choice of imaging uation
of intraorbital
and
to sur-
abscess
fractures
recommends
cnQ
.
studies foreign
abscesses.
MR imaging
ology
extruded
nated
the
Wood
is often
Clostridium
immunization
tetani,
should
be
infallible
(16,17).
9.
in evab-
bodies
10.
problems
such
Green
et al (5)
if plain
radi-
Weinstein
MA,
Berlin
wood
11.
MT.
2.
Latehaw
RE, ed.
of the head, 3.
4.
as 5.
Computed
neck and spine.
Chicago: eds.
Year
12.
13.
Green
BF, Kraft
traorbital wood: onanee imaging. 608-611.
SF, Carter
KD, et al.
clinical
15.
Ossoinig
Arch Otolaryngol
KC. (letter).
L, Schatz in penetratretained for-
1983; 109:
tomography Aeta Radiol
of in1987;
Detection of wood foreign Ophthalmology 1991; 98:
Grove SG Jr. Orbital trauma. In: Spaeth G, ed. Ophthalmic surgery: principles and practice. 2nd ed. Philadelphia: Saunders, 1990; 496-497. Wesley RE, Wahl
JW, LodenJP,
Management
ies in the orbit. 932.
17.
RC,
intracranial
PJ, Schut
265-268. Lindahl S. Computed traorbital foreign bodies. 28:235-240.
RR.
16.
Plast
limitations of comJ Neurosurg 1988;
tomography.
68:752-756. Weisman RA, Savino
bodies 274.
Cranial
computed tomography. St Louis: Mosby, 1985; 569-573. Myllyla V, Pyhtinen J, Paivansalo M, Tervonen 0, Koskeba P. CT detection and location of intraorbital foreign bodies: experiments with wood and glass. ROFO 1987; 146:639-643.
Ophthalm
Penetrating
wounds:
eign bodies.
tomography
Book Medical, 1985; 369. Williams AL, Haughton VM,
orbit.
NJ. Computed tomography ing wounds of the orbit with
Berlin
LA. Orbits. In: Haaga JR. Alfidi RJ, eds. Computed tomography of the whole body. St Louis: Mosby, 1983; 309.
in the
RA.
puterized
knowledge
AJ, Modic
bodies
Reconstr Surg 1990; 6:108-114. Hansen JE, Gudeman 5K, Holgate
so tetanus
14. 1.
computerized tomography in the detection of intraorbital foreign bodies. Computerized Tomogr 1977; 1:151-156. Glatt HJ, Custer PL, Barrett L, Sartor K. Magnetic resonance imaging and computed tomography in a model of wooden
Saunders
that wood has variable appearances and can mimic air at CT will increase the accuracy of diagnosis. U
is
Neurol 1984; 21:236-238. Bodne D, Quinn SF, Cochran CF. Imaging foreign glass and wooden bodies of the extremities with CT and MR. J Comput Assist Tomogr 1988; 12:608-611. Kadir 5, Aronow 5, David KR. The use of
contami-
established
The
Jooma R, Bradshaw JR, Coakham HB. Computed tomography in penetrating eranial injury by a wooden foreign body. Surg
foreign
(10). The use of thin-section two-plane (axial and coronal) CT and variable window widths is extremely useful in deteetion of wood foreign bodies and associated injuries and complications, but is not
8.
foreign
Sometimes, retained bodies are spontaneously
(15).
with
and
7.
References
of associated and
followed
removed. foreign
for-
controversial. Ossoinig (13) suggested standardized ophthalmic ultrasonography (US) (combined use of standardized A-sean and B-scan) should be used first, while Hansen et al (10) recommended CT as “the single most effective test and should be the primary diagnostic examination in suspected penetrating orbital and cranial wounds.” CT also allows detection
surgically
body wood
6.
of wooden South
Med
J
Tate E, Cupples H. Detection foreign bodies with computed
Henderson
foreign 1982;
bod-
75:924-
of orbital tomogra-
phy: current limits. AJR 1981; 137:493-495. Woolfson JM, Wesley RE. Magnetic reso-
nance imaging and computed tomographic scanning of fresh (green) wood foreign bodies in dog orbits. Ophthalmic Plast Reeonstr
Surg
1990;
6:237-240.
In-
detection by magnetic resOphthalmology 1990; 97:
November
1992
