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Imaging of Facial Trauma Part 2: Introduction and Anatomy Rathachai Kaewlai, MD www.RadiologyInThai.com Created: January 2007 "1 Outline Facial fracture epidemiology Types of facial fracture Nasal bone fracture Initial management Naso-orbital-ethmoid fracture Frontal sinus fracture Imaging: CT versus radiography Orbital fracture Zygomatic fracture Normal anatomy Maxillary fracture 3D Mandibular fracture CT (axial, coronal and sagittal planes) Radiography Imaging approach Biomechanics 2 Plain Film Radiography Can be obtained to screen for facial injury if CT is not immediately available If plain film identify a fracture other than a simple nasal bone fracture, further evaluation by CT is indicated Multiple plain film projections are relative to ‘canthomeatal line’; an imaginary line drawn from outer canthus to external auditory meatus Proper positioning (of patient’s head), alignment of x-ray beam is critical for evaluation because facial skeletal anatomy is complex 3 Plain Film Radiography Remember: plain film is a 2D image of a 3D object Overlapping structures significantly obscure anatomic detail This problem is solved by standard views (to minimize overlap, allow visualization of important structures, familiarity for interpretation) Rule of symmetry: two sides of the face are quite symmetrical Symmetry is usual, and asymmetry is suspect Multiplicity: fractures of facial bones are frequently multiple. Do not stop looking for others when see one 4 Plain Film Radiography Facial series Mandible Water’s view (PA view with cephalad angulation) Oblique view, Towne’s view Caldwell view (PA view) Orthopanthogram Towne’s view Lateral view Base view Additional view Lateral view of the nasal bone (nasal technique) Note: The lecture series are focused on CT scan 5 Water’s View The most comprehensive single projection display Excellent view of - Maxilla - Maxillary sinuses - Zygoma - Zygomatic arches - Rims of orbits, esp. floor - Nasal bones 6 Water’s View Key structures 1 = Frontal sinus 2 = Maxillary sinus 3 = Frontal process of Zygoma 4 = Body of Zygoma (malar eminence) 5 = Temporal process of Zygoma Dotted line = zygomatico-frontal suture Dolan’s lines of reference Line A, B, C Rule: smooth, non-disrupted, same contour on both sides 7 Line A - Begins at inner surface of zygomatico-frontal suture, follows orbital surface of zygoma, maxilla, frontal process of maxilla and arch of nasal bone - If drawn to both sides, the line is similar to lazy ‘W’ or half frame of reading glasses Line B - Begins at lateral and inferior margin of maxilla and extends along lateral wall of maxillary sinus and inferior surface of zygomatic arch - Ends at glenoid fossa 8 Line C - Begins at lateral and inferior margins of maxilla, extends along lateral wall of maxillary sinus and inferior surface of zygomatic arch - Ends at glenoid fossa “Friendly Line” - Medial half of Line C is the anterolateral wall of the maxillary sinus. - If it is disrupted, the possibilities of fx include 1) Isolated maxillary antrum 2) Zygomatico-maxillary complex (ZMC) 3) LeFort (unilateral or bilateral) 9 Caldwell’s View Excellent view of - Entire rim of orbit, esp. superomedial rim - Ethmoid sinus - Floor of orbit may be well seen in petrous bones are projected below the inferior orbital rim (not in this example) 10