Transcript Facial Bones Power Point

Facial Bone
Radiography
A five minute guide
to what the
radiologist and
clinician really need.
Facial Bone Radiography
• Severe trauma to the facial area usually
proceeds to CT with 2D and possibly 3D
reconstructions.
• Facial radiographs remain a useful screening
tool for lesser trauma with the advantages of
lesser cost and radiation.
• If you don’t perform these often and are faced
with the exam on the night shift – don’t
despair – here is your guide.
• A good facial bone exam is based primarily on
three projections:
• Lateral
• True Waters
• Modified Caldwell
• A SMV view is added in some protocols.
• The key to a good exam is to take the images
correctly and produce the expected view of
the anatomy.
THE LATERAL PROJECTION
• The lateral view should be taken upright if
possible. A cross table lateral without turning the
head is the next best choice.
• Turning the patients head is not a good plan with
acute trauma but, more importantly, a rotated
projection can mask clues to a basilar skull
fracture and doesn’t allow a correct view of the
cervical/cranial junction.
• Right and Left laterals are not as important as a
patient with a suspected skull Fx will get a CT.
• This lateral view was
taken with the head
turned to the side on
the table.
• An air-fluid level in the
sphenoid sinus is a clue
to a possible basilar
skull fracture which
would be missed as the
fluid would spread out
in the dependant
portion of the sinus.
• This correctly
positioned lateral
displays well the
relationship of the skull
base to the cervical
spine.
• An air fluid level in the
sinuses would be
evident.
Another good lateral. Did you note the air-fluid levels in
the maxillary sinuses? These can be due to sinusitis but
in the setting of acute trauma may be a clue to bleeding
and an orbital floor fracture.
THE WATERS VIEW
• A waters view by definition should show the entire
maxillary sinuses. Faces are different! A common
mistake is to plug in a standard angle which ends up
being too shallow. If a standard angle does not show
the entire sinuses, it should be repeated. This view
shows the anterior orbital rims (not the orbital floor)
and gives the radiologist a good view of the
zygomatic arches, zygomas and orbital roofs.
Differentiation between an orbital rim Fx and an
orbital floor Fx is important to the clinician.
Correctly positioned Waters. Z=zygoma,
OR=orbital rim, ZA= zygomatic arch and
ms=maxillary sinus. Note that the entire
maxillary sinus is displayed.
THE CALDWELL PROJECTION
The Caldwell view is the only projection to
visualize the true orbital floor where blowout
fractures and sometimes entrapment of the
extraocular muscle occurs. The standard
Caldwell will not show the orbital floor well
and a modified Caldwell with steeper angle is
needed. In most patients, this is around 22
degrees. The ideal projection places the
petrous ridges just below the orbital floor.
This standard, 15 degree
Caldwell shows the
petrous ridges (PR)
above the lower orbit
and obscures detail of
the true orbital floor. It
should be repeated
with additional angle of
around 8 degrees.
This is the anatomic view
you want to produce for
a good modified
Caldwell. A lesser angle
obscures the orbital
floor and a steeper
angle approaches a
Waters and shows the
orbital rim instead of
the floor.
Modified Caldwell
If an orbital floor fracture is found, patients should
proceed to CT to evaluate possible muscle
entrapment and fragment position. This CT
coronal image shows a left orbital floor depressed
fracture with entrapment of the inferior rectus
muscle. The patient went to surgery to relieve the
entrapment and diplopia.
A case can be made for a facial bone protocol using just the previous three well
positioned images. Our present protocol also includes a submental vertex view
which gives the radiologist an additional look at the zygomatic arches.
• GOOD POSITIONING
• MAKES EVERYONE HAPPY!