Fig. 1.1
Normal images of orbit. (a) Posteroanterior, (b) lateral
1.1.2 Normal X-ray Presentations on Dacryocystography
Dacryocystography is used to explore the shape, size, and obstruction (including the severity and location of obstruction) of dacryocyst. Iodine allergy test is required for the patients receiving dacryocystography. The normal nasolacrimal duct is unobstructed; thus, contrast agent could flow to inferior meatus rapidly, and only small amount of contrast agent could be found in the regions of dacryocyst and nasolacrimal duct; in addition, contrast agent could also be found in nasal cavity (Fig. 1.2).
Fig. 1.2
Dacryocystography of the right side. (a) Posteroanterior, (b) lateral
1.2 Computed Tomography (CT)
CT scanning is the most commonly used technology for the examinations of orbit, which could clearly display the anatomic structures, especially the bony structures in ocular region. For the patients with traumatic injuries, three-dimensional CT scanning could directly display the shape of the orbital injuries and thus helps deciding operation plan.
Currently, multi-row spiral CT scanning is routinely used for the CT scanning of orbit, after which the raw images are used for multi-planar reconstruction. Cross-sectional and coronary images are the most commonly reconstructed images. For the patients with posterior orbit wall lesions or postocular lesions, oblique sagittal reconstruction is an effective supplement (Goh et al. 2008). The anatomic features of orbit at the major levels on CT images are described as follows (Fig. 1.3):
Fig. 1.3
The normal orbit by CT scan (Axial CT (a–d), Coronal CT (e–i), Coronal CT (bone window) (j–l), Sagittal CT (m, n)). (a) 1 superior of the eyeball, 2 lacrimal gland, 3 superior rectus, 4 superior margin of the orbit, 5 posterolateral wall of the orbit; (b) 1 eyeball, 2 lacrimal gland, 3 medial rectus, 4 optic nerve, 5 eyelid, 6 ophthalmic artery; (c) 1 atria, 2 lens, 3 vitreum, 4 optic nerve, 5 lateral rectus, 6 superior orbital fissure, 7 lacrimal gland, 8 media rectus; (d) 1 atria, 2 vitreum, 3 inferior rectus, 4 inferior orbital fissure, 5 pterygopalatine fossa, 6 lens, 7 media rectus, 8 posterolateral wall of the orbit, 9 greater wing of sphenoid bone; (e) 1 vitreum, 2 lens, 3 lacrimal sac area, 4 orbital process of frontal bone, 5 eye thimble; (f) 1 lacrimal gland, 2 vitreum, 3 the insertion of media rectus, 4 inferior obliquus, 5 nasolacrimal duct, 6 the insertion of superior rectus, 7 the insertion of lateral rectus, 8 the insertion of inferior rectus; (g) 1 superior muscle group of orbit, 2 lacrimal gland, 3 vitreum, 4 inferior rectus, 5 superior obliquus, 6 media rectus; (h) 1 superior muscle group of orbit, 2 superior ophthalmic vein, 3 superior obliquus, 4 media rectus, 5 inferior rectus, 6 ophthalmic artery, 7 optic nerve, 8 lateral rectus, 9 infraorbital canal; (i) 1 anterior clinoid process, 2 orbital apex, 3 inferior orbital fissure, 4 pterygopalatine fossa, 5 lesser wing of sphenoid bone, 6 superior orbital fissure, 7 greater wing of sphenoid bone, 8 sphenoid sinus, 9 pterygomaxillary fissure; (j) 1 frontal sinus, 2 paries superior orbitae, 3 the upper inner corner of paries superior orbitae, 4 ethmoidal sinus, 5 the lower inner corner of paries inferior orbitae, 6 nasolacrimal duct, 7 maxillary sinus; (k) 1 optic canal, 2 anterior clinoid process, 3 greater wing of sphenoid bone, 4 foramen rotundum, 5 sphenoid sinus, 6 the superior wall of optic canal, 7 superior orbital fissure, 8 orbital apex, 9 medial and lower wall of optic canal; (l) 1 optic canal, 2 anterior clinoid process, 3 orbital apex, 4 foramen rotundum, 5 sphenoid sinus, 6 planum sphenoidale, 7 middle cranial fossa, 8 greater wing of sphenoid bone, 9 vidian canal, 10 processes sphenoid bone pterygoid; (m) 1 lacrimal gland, 2 vitreum, 3 lateral rectus, 4 maxillary sinus; (n) 1 superior muscle group of the orbit, 2 optic nerve, 3 anterior chamber, 4 lens, 5 vitreum, 6 inferior rectus
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