Plain Films

Radiographic evaluation of severe facial trauma requires some essential radiographic projections and, although CT with three-dimensional reformatting has become the imaging modality of choice in complex facial trauma, plain films are still widely used in the initial evaluation of the trauma patient. The facial bone series consists of three to five projections, including the lateral cephalic, Caldwell’s lateral oblique, and Waters’ views. The submentovertex (SMV) and Towne’s view can also be obtained to help delineate fractures not seen on the other views (Fig. 12-2).

Towne’s view is the most useful for assessing subcondylar fractures because it is the only plain radiographic study that optimally demonstrates lateral or medial angulation and/or displacement in these fracture patterns (Fig. 12-3). It is also useful for the evaluation of the orbits because it provides optimal demonstration of the inferior orbital fissure. Towne’s view also provides additional exposure of the maxillary sinuses and inferior orbital rims, aiding in the postoperative evaluation after fracture repair. When Towne’s view is obtained from a posteroanterior (PA) angulation it is useful to evaluate areas such as the petrous ridges and mastoid air cells, as well as the foramen magnum, dorsum sellae, and occipital bone.⁶ In the reverse Towne’s projection, which is a reverse of the half-axial or Towne’s view, the same fracture patterns seen on the PA Towne’s view can be observed.⁷

Lateral cephalic views can provide information for evaluation of the airway, retropharyngeal soft tissue, anterior and posterior maxillary antral walls, and anterior alveolar ridge, as well as fractures involving the midface, such as LeFort I, II, and III fractures and nasal fractures (Fig. 12-4). PA films are also useful for evaluating midface and mandibular fractures (Fig. 12-5). The Caldwell view is used for evaluation of the midface and paranasal sinuses and provides the best view of the orbits and posterior facial structures. This view is particularly useful for evaluating the nasofrontal and vertical segments of the zygomatic buttresses, nasal fossa, and mandible. Lateral oblique views can be used for evaluation of the mandibular angle and condyles. Waters’ view is useful for evaluating the midface and delineating fractures of the orbital rims, zygomatic arches, and anterior facial structures. The SMV view provides a good view for zygomatic arch and midface fractures.

As supplemental films, the panoramic radiograph is extremely useful when evaluating for mandibular fractures, including fractures of the condyle. In addition, occlusal films can be used to evaluate dentoalveolar injuries.

Cervical Spine Films

In cases of facial trauma, cervical spine (C-spine) injuries should be ruled out with a complete cervical spine series, which includes lateral view (cross table), odontoid (open mouth), and oblique views before any manipulation of the neck. Undiagnosed cervical spine injury can occur in 15% to 30% of patients and lateral views have a false-negative rate of 26% to 40%.⁸ In equivocal clinical cases, CT is recommended because it identifies more fractures and is more accurate in locating the position of bone fragments. CT scans are also recommended for all unconscious patients with suspected neck trauma and all alert conscious patients who complain of neck pain and spasms after high-velocity injuries. CT, however, is not adequate for identifying ligamentous injuries in the cervical spine and, although they can be identified in flexion-extension lateral views, this is a potentially hazardous procedure. It must be done only for alert and cooperative patients with minimal spasm who have no evidence of a potentially unstable fracture on plain film or CT imaging. MRI, on the other hand, can identify ligamentous injuries and should be considered if the previous investigations remain unhelpful or cannot be undertaken.

One of the primary purposes of C-spine imaging is to identify potentially unstable injuries; one of the most helpful classifications of instability has been proposed by Denis.⁹ This classification divides the spine into three columns (Fig. 12-6):

An injury is considered unstable if two or three columns are disrupted. An alert asymptomatic patient without a distracting injury or neurologic deficit, and who can complete a functional range of motion evaluation, may safely be cleared from cervical spine immobilization, even without radiographic evaluation.¹⁰

Computed Tomography

Although plain films will often provide adequate information, CT scans will often yield additional information or can be used when C-spine precautions or other injuries do not permit standard facial films. There is wide agreement that the exact anatomic identification and quantification of facial fractures, recognition of the true extent of bone displacements, and precise assessment of major bone and soft tissue complications can be effectively and accurately imaged with high-resolution CT.¹¹

Since the introduction of CT in the late 1970s and early 1980s, there have been major advancements in the diagnostic imaging of maxillofacial injuries. CT scanning allows for the visualization of injuries of each of the osseous components of the facial skeleton in the axial and coronal planes and allows for the evaluation of various soft tissue injuries. Continued improvements in software have enabled multiplanar reconstruction of image slices in various planes using the digitized data obtained in the initial axial evaluation. These advances in computer technology enable automatic reconstruction of surface models using digitized contour lines and three-dimensional representation on a graphic terminal (Fig. 12-7). Three-dimensional reconstruction of facial bones from two-dimensional images can help guide treatment of facial injuries; in addition to trauma, it is helpful for the evaluation of congenital malformations and pathology.

Although two-dimensional CT scans can be helpful when evaluating facial trauma, one of the difficulties is obtaining coronal sections because they require significant movement of the patient’s neck. Thus, the examination is restricted to axial sections and the impossibility of obtaining sagittal sections requires the additional use of conventional tomography.¹² Interpretation of three-dimensional reconstruction allows for easier evaluation and the use of three-dimensional images for the assessment of facial injuries ensures a high degree of reliability in morphologic diagnosis.

CT can also be useful to rule out neurologic injury in the maxillofacial patient and thus can be used to supplement the facial injury evaluation. This imaging is also the most useful in acute situations because of the rapid acquisition times, excellent detail of bone, and ability to examine anatomy in multiple planes. CT scans should also be considered in patients in whom plain films are difficult to assess. For example, midface fractures are difficult to evaluate with plain radiographs because of the overlap of anatomic structures. In these cases, CT scans in several spatial planes of space—axial and coronal and possibly three-dimensional reconstruction—should be considered.

With the increasing role of CT for the assessment of trauma patients, most clinicians advocate its use. It is considered the gold standard for radiographic evaluation of the facial trauma patient. In the past, the use of traditional or single-slice acquisition CT produced images by data collected from detectors after a 360-degree rotation. After each tomographic image, the patient table was moved and another image obtained. A time delay of 10 to 15 seconds between each slice was necessary, which made image acquisition a slower process. The development of spiral or helical scanning has allowed for faster image acquisition.13,14 Spiral CT involves the simultaneous movement of the patient table and x-ray tube, which results in a volume acquisition of data from which individual tomographic images can be reconstructed. Because a volume data set is acquired, excellent multiplanar reformations are possible when using thin image slices (≤3 mm).⁹ Thus, spiral CT scanners can rapidly scan acutely traumatized patients in less than 1 minute and can generate direct images in the scan plane and three-dimensional images in a matter of seconds.

Multidetector CT is another improvement over spiral CT; whereas spiral CT uses a single row of detectors, multidetector CT uses a matrix of detectors that allows for the acquisition of multiple tomographic images per revolution, which greatly increases the speed of imaging. Also, fracture detection has been shown to be significantly higher with thin multiplanar reformations.¹⁵ These are currently considered state of the art imaging for the patient with severe maxillofacial injuries.

Although CT scans of maxillofacial injuries have proven to be invaluable for the diagnosis and treatment of these fractures, one must remember that a treatment plan is based on other variables, including the patient’s age, physical status, and preexisting conditions. CT scans should be used as an adjunct in the development of the treatment plan.

Computed Tomography Angiography

CT angiography (CTA) is an important tool in the maxillofacial field for a variety of indications, ranging from the management of traumatic injuries to the treatment of pathologic conditions such as vascular malformations or vessel aneurysms. CTA in combination with MR angiography (MRA) is highly efficient for the diagnosis of most arterial and venous traumatic lesions in the acute setting and when patients develop delayed symptoms. Conventional angiography is mainly recommended for therapeutic purposes or when the diagnosis remains unclear after performing cross-sectional imaging.¹⁶ Taking into consideration that approximately 25% of penetrating injuries to the neck result in vascular injury, in addition to an 80% chance of carotid artery injury and a 43% chance of vertebral artery injury in the trauma patient, the development of vascular imaging techniques has been beneficial for the diagnosis of these injuries.

Additional diagnostic modalities include dacrocystography, ultrasound, and sialography, which become useful in the delayed management of lacrimal/salivary duct injury.¹⁷ Currently, multidetector row CT provides isotropic data acquisition, allowing imaging reformats with high resolution. This provides an excellent noninvasive evaluation of the major vascular structures of the head and neck regions. Studies have reported 100% sensitivity and 98% specificity in diagnosing vascular occlusion, pseudoaneurysms, fistulas, and partial thrombosis.⁷

Magnetic Resonance Imaging

MRI has become the preferred diagnostic tool for examination of the soft tissue structures of the extracranial head and neck. In the early 1980s, the first MRI scan became available after the independent and simultaneous work of Felix Bloch and Edward Purcell in the 1940s, which led to their being awarded the Nobel Prize for Physics in 1956.¹⁸

Magnetic resonance is a dynamic and flexible technology that allows one to tailor the imaging study to the anatomic part of interest and disease process being studied. With its dependence on the more biologically variable parameters of proton density, longitudinal relaxation time (T1), and transverse relaxation time (T2), variable image contrast can be achieved by using different pulse sequences and by changing the imaging parameters. Signal intensities on/>