Computed tomography in traumatic orbital emergencies: a pictorial essay-imaging findings, tips, and report flowchart

Abstract

Computed tomography (CT) is considered the gold standard technique for the assessment of trauma patients with suspected involvement of the eye and orbit. These traumas can result in dramatic consequences to visual function, ocular motility, and aesthetics. CT is a quick and widely available imaging modality, which provides a detailed evaluation of the orbital bony and soft tissue structures, an accurate assessment of the globes, and is used to guide the patients' treatment planning. For a timely and accurate diagnosis, radiologists should be aware of fracture patterns and possible associated complications, ocular detachments and hemorrhages, and different appearances of intraorbital foreign bodies. This educational review aims to describe all post-traumatic orbital abnormalities that can be identified on CT, providing a list of tips and a diagnostic flowchart to help radiologists deal with this complex condition.

Keywords: Orbital emergencies; Orbital foreign bodies; Orbital fractures; Orbital trauma; Tomography (X-ray computed).

Fig. 1

Coronal CT reconstructions. a Blow-out fracture of the left orbital floor (arrow) with herniation of the intraorbital fat into the maxillary sinus. Presence of intraorbital emphysema, an indirect sign of fracture (empty arrows). b Coronal reconstruction of the follow-up CT 2 months after the orbital wall reconstruction through the position of an absorbable mesh. The integrity of the orbital floor is restored (white arrow); the soft tissue herniation is no longer present

Fig. 2

Coronal CT reconstruction with bone (a) and soft tissues (b) algorithms of an isolated orbital floor fracture. a Right orbital floor fracture with involvement of the medial aspect of the infraorbital groove (white arrow) and dislocation of a bony fragment into the maxillary sinus (empty arrow). b Mild swelling of the right inferior rectus muscle (arrowhead) partially herniated into the bony defect; huge herniation of the intraorbital fat through the fracture gap; within the herniated soft tissue, hematomas are recognizable (asterisks)

Fig. 3

Coronal CT reconstruction with bone (a) and soft tissues (b) algorithms of an orbital floor fracture associated with a lamina papyracea fracture. a Left orbital floor fracture with huge bone defect (arrow), associated with medial wall fracture (white asterisk). b Herniation of the intraorbital soft tissues into the maxillary sinus (white asterisk). The inferior rectus muscle is dysmorphic, elongated, and also partially herniated caudally into the sinus (arrow). In the lower portion of the herniated tissue, a small hematoma is present (arrowhead). The medial rectus muscle (white asterisk) is swollen and partially entrapped in the fracture of the lamina papyracea (empty arrow)

Fig. 4

Coronal CT reconstruction with bone (a) and soft tissues (b) algorithms in a patient with a current fracture of the right orbital medial wall (white arrow) and a previous fracture of the contralateral orbital medial wall (empty arrow). a Huge bone defect of the right lamina papyracea (white asterisk). On the left side, discontinuation of the lamina papyracea caused by a previous fracture is visible, as well as the herniation of the intraorbital fat tissue into the ethmoidal cells (empty arrow). b The medial rectus is thickened and partially displaced through the bone defect (arrow). The left medial rectus muscle shows regular site and morphology (empty arrow)

Fig. 5

Axial CT acquisition with bone (a) and soft tissues (b) algorithms in a patient with a current fracture of the right orbital medial wall (white arrow) and a previous fracture of the contralateral orbital medial wall (empty arrow). a Extensive discontinuation of the right lamina papyracea (white arrow). b The medial rectus muscle is swollen, displaced medially, and partially entrapped into the fracture (asterisk); presence of hemosinus, visible as a right posterior ethmoidal cell occupied by hyperdense material (blood) (arrow)

Fig. 6

Coronal CT reconstruction with bone (a) and soft tissues (b) algorithms of an orbital bone fracture. Non-displaced fracture of the orbital roof (white arrow) (a), associated with intracranial complications: in figure b, a small frontal intraparenchymal brain hematoma is visible as a focal hyperdensity (empty arrow)

Fig. 7

Axial CT acquisition with bone (a) and soft tissues (b) algorithms of a pure fracture of the left lateral orbital wall (white arrow). Slightly displaced fracture of the lateral orbital wall with adjacent intraorbital small air bubbles. A small bony fragment (empty arrow) presents contact with the lateral rectus muscles, that preserves regular morphology and thickness. Hematoma of the subcutaneous soft tissue (asterisk)

Fig. 8

3D reconstructions of a left zygomaticomaxillary complex fractures. Fractures of the lateral orbital wall (white arrow), of the orbital floor (empty arrow), multifocal fracture of the zygomatic arch (black arrows)

Fig. 9

Coronal reconstruction with the bone algorithm of a left lateral orbito-zygomatic fracture. Coexistence of fracture of the orbital floor and the lateral wall (white arrows), fracture of the lateral wall of the left maxillary sinus (empty arrow), and fracture of the zygomatic arch, with medial intraorbital displacement. Presence of intraorbital emphysema (arrowhead) and hemosinus (asterisk)

Fig. 10

Coronal reconstruction (a) and axial CT acquisition (b) of a Naso-orbitoethmoidal Complex Fracture. Coexistence of a fracture of the right orbital floor with the involvement of the infraorbital groove (white arrow, figure a) and of a fracture of the lower third of the right lamina papyracea (empty arrow, figure a), and of a fracture of the nasal septum (arrow) and of the left nasal bone (empty arrow) in figure (b). Evidence of intraorbital (white arrowheads, figure a) and soft tissue (white asterisks, figure a, b) emphysema

Fig. 11

3D reconstructions of Le Fort Fractures. Both patients presented with Le Fort I fracture (black arrows), with horizontal maxillary fracture which passes through the alveolar ridge, lateral nose, and inferior maxillary sinuses wall, separating the teeth from the upper face. Patient a also showed a right Le Fort III fracture (white arrows), also known as craniofacial disjunction, consisting of fractures involving the nasofrontal suture, maxillo-frontal suture, orbital wall, and zygomatic arch/zygomaticofrontal suture. Patient b showed a Le Fort II (empty arrows), with a pyramid shape, with a fracture line involving the nasofrontal junction, the alveolar ridge, and the lateral wall of the right maxillary sinus

Fig. 12

Axial CT acquisition reconstructed with soft tissue algorithm in an orbital blunt trauma with fracture of the left lamina papyracea, in a patient who complained left visual loss. The left optic nerve is stretched, mildly swollen, and hyperdense (white arrow). These findings are suggestive for post-traumatic optic neuropathy. The globe is surrounded by a hyperdense hematoma (asterisks), extended in the retro-orbital fat tissue next to the optic nerve

Fig. 13

Axial CT acquisition showing a left hyphema, visible as a hyperdense (hemorrhagic) focal component in the anterior chamber, anterior to the lens (white arrow). The content of the contralateral chamber is homogeneous and hypodense (empty arrow)

Fig. 14

Axial CT acquisition. Left vitreous hemorrhage visible as a diffuse inhomogeneous hyperdensity of the left eyeball (arrow)

Fig. 15

Axial CT acquisition of a retrobulbar hemorrhage visible as a retrobulbar inhomogeneous hyperdensity (white arrow). Diffuse thickening of the left palpebral subcutaneous soft tissues

Fig. 16

Two cases of post-traumatic lens detachment and dislocation. The left lens (a) and the right lens (b) are not recognizable in their normal sites and are displaced posteriorly (white arrows). Well-defined hyperdensity related to intraocular silicone oil (black asterisk), due to a previous surgical intervention for a retinal detachment in the right globe in (a)

Fig. 17

Axial CT acquisition reconstructed with soft tissues algorithm showing a left retinal detachment. Evidence of folded membranes with hyperdense fluid in the subretinal space (white arrows). The detachment converges posteriorly on the optic disc (asterisk)

Fig. 18

Axial CT acquisition reconstructed with a soft tissue algorithm of a choroidal detachment with choroidal hemorrhage, visible as hyperdense lentiform component on CT (white arrows), that diverges approaching to the optic disc (compared to the retinal detachment that converges to the optic disc)

Fig. 19

Axial CT acquisition reconstructed with soft tissue algorithm of two examples of post-traumatic open globe injuries of the right (a) and left (b) eye. The affected globes are dysmorphic and show volume loss, particularly the one in case (b). The globe borders are irregular due to scleral interruptions (white asterisks). The anterior contour of the globes is flattened (white arrow). Evidence of irregular vitreous hemorrhagic hyperdensities (black asterisks). Bilateral thickening of the palpebral soft tissues

Fig. 20

CT appearance of the various ocular interventions that can mimic open globe fractures and/or vitreous hemorrhages. 32-Year-old patients with an increase of the anteroposterior diameter of the left eyeball, related to a myopic eye, previously treated for e retinal detachment, with current CT evidence of intraocular air-bubble-like components (white arrows), corresponding to perfluoropropane gas bubbles (a). b Coronal CT reconstruction showing a scleral buckle surgery with low attenuation device (black arrow) that mildly indents the temporal aspect of the left globe and encircles the scleral buckle (metallic density ring around the left globe, white empty arrows). c. highly attenuation silicone oil in the left globe (asterisk) placed after surgical vitrectomy to treat a retinal detachment. To help the differential diagnosis with hemovitreous, the attenuation values in Hounsfield Units (HU) can be assessed, with silicone oil having values greater than 100 HU

Fig. 21

Two examples of radiopaque foreign bodies, with intraorbital (a) and intraocular (b) location. a Sagittal reconstruction with bone algorithm showing an intraorbital hyperdense foreign body (a piece of a glass bottle) embedded in the orbital floor (white empty arrow). b Axial acquisition reconstruction with bone algorithm showing an intraocular foreign body causing beam hardening artefacts (metal fragments in a welder, due to an accident at work) (white empty arrow). c, d Show possible mimickers of foreign bodies: in c, bilateral scleral plaques visible as calcifications near the scleral insertion of the extraocular muscles (white arrows); bilateral presence of intraocular lens implants for previous cataract surgery, that are smaller, thinner and less dense compared to the normal lenses. In d, bilateral presence of drusen (white arrowheads), visible as focal calcifications in the optic nerve head

Fig. 22

Flowchart showing the radiological approach to the analysis of post-traumatic orbits CT examinations

Fig. 23

Coronal reconstruction showing the presence of retrobulbar emphysema due to a fracture of the right lamina papyracea, visible as air within the upper right orbit, that mimics the appearance of an eyebrow (asterisk). This is an important indirect sign of orbital bone fracture [42]