Emergency Imaging. Alexander B. Baxter

Emergency Imaging

for suspected in-ﬂammatory or neoplastic disease.

Facial trauma is common, and in this set-ting the radiologist’s goals are to describe fractures and their displacements, iden-tify speciﬁc fracture patterns, anticipate injuries to adjacent soft tissue structures, and communicate ﬁndings eectively to the surgeon. In the face, the most impor-tant fracture patterns include nasal and naso-orbito-ethmoid (NOE), zygomatico-maxillary (ZMC) complex fractures, Le Fort fractures, orbital wall fractures, and man-dibular fractures.

Noncontrast CT is the primary imaging study for facial trauma, and multiplanar reformations are essential for accurate in-terpretation. Three-dimensional recon-structions aid in surgical visualization and should be included if available. All facial fractures should be individually listed in the report and assigned to whichever frac-ture pattern they most closely correspond. It is unusual for an acute fracture to involve a sinus wall without intrasinus hemor-rhage. Intraorbital air indicates an orbital wall fracture and potential for complicat-ing orbital infection. If the pterygoid plates are intact, all of the Le Fort fractures are excluded.

Facial Trauma Checklist

First Look

• Blood in sinuses?

• Blood in mastoid air cells?

• Pterygoid fracture?

• Orbital emphysema?

• Orbital hematoma or fat stranding?

Bone Survey

• Frontal sinus

• Nasal bones

• Ethmoid air cells

• Medial orbital walls (with attention to the nasolacrimal duct and attachment of the medial canthal ligament)

• Orbital rim

• Zygomatic arch

• Zygomaticofrontal suture

• Lateral orbital wall

• Orbital ﬂoor

• Orbital roof

• Pterygoid plates (involvement of the pterygoid plates deﬁnes the Le Fort fractures)

• Maxillary alveolus

• Maxillary sinus walls

• Mandible and temporomandibular joints

• Teeth

• Sphenoid sinus

• Carotid canals

• Mastoid air cells

• Petrous temporal bone (cochleae, vestibule and semicircular canals, ossicles)

84Emergency Imaging

Approach to Inammatory or Neoplastic Conditions

Suspected inﬂammatory or neoplastic conditions of the face and neck should be evaluated using postcontrast CT. Because of its anatomic complexity, neck CT in-terpretation is aided by grouping related structures.

Nontraumatic Face/Neck Checklist

Airway and Related Structures

• Nasal cavity

• Nasopharynx

• Oropharynx

• Hypopharynx

• Larynx

• Trachea

• Lung apices

• Esophagus

• Thyroid gland

Soft Tissues and Bones

• Muscles

• Blood vessels

• Lymph nodes

• Cervical spine and skull base

Oral Cavity and Salivary Glands

• Tongue

• Tongue base

• Mandible, maxilla, and dentition

• Floor of mouth

• Submandibular glands

• Parotid glands

Orbits

• Globes

• Muscles

• Optic nerve

• Orbital fat

• Orbital walls

Everything else

• Skull base

• Brain

• Temporal bones

Soft Tissue Survey

• Superﬁcial soft tissues

• Nasal septum

• Sinus contents

• Orbital fat (with attention to any orbital stranding, emphysema, or subperiosteal hematoma)

• Globes

• Optic nerves

• Extra-ocular muscles

• Brain (pneumocephalus, hemorrhage)

Indications for Neck CT Angiogram in Trauma

Blunt neck trauma is associated with clini-cally occult vascular injury in up to 3% of hospitalized patients. Early detection of vascular injury and therapeutic antico-agulation or endovascular occlusion can signiﬁcantly reduce the incidence of stroke in this group. The Denver Modiﬁed Blunt Cerebrovascular Screening Criteria deﬁne a high-risk group of trauma patients for whom urgent CT angiographic imaging is indicated:

• Direct signs of vascular injury (hemorrhage, bruit, hematoma)

• Focal neurologic deﬁcit or CT demonstrating acute cerebral infarct.

• Le Fort II or III fracture

• Cervical spine fracture

• Basilar skull fracture involving carotid canal

• Severe brain injury (diuse axonal injury, GCS < 6)

• Hanging injury• Neck contusion

Patients with penetrating injuries who do not undergo immediate surgical ex-ploration should be imaged by CTA or conventional angiography. Typical vascu-lar injuries in both blunt and penetrating trauma include dissection, occlusion, pseu-doaneurysm, and arteriovenous ﬁstula. Urgent CTA should also be considered in patients who present with focal neurologic ﬁndings, as vascular dissection with mini-mal or no trauma is an important cause of stroke, particularly in younger adults.

3 Head and Neck

◆Imaging and AnatomyImaging

Face CT (Noncontrast Helical)

Indications: Facial, orbital, or mandibular trauma.

Technique: 0.6-mm dataset with 1–2-mm axial, 2-mm sagittal, and 2-mm coronal reformations of head, face, and cervical spine. Oblique sagittal images, 1 mm, along the course of the optic nerve may be obtained for evaluation of orbital pathology. Images obtained from orbital roof to hyoid (unless obtained in conjunction with head and cervical spine CT).

Face CT (Helical + Contrast)

Indications: Orbital cellulitis, suspected facial abscess, mass.

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