This document provides recommendations for imaging the orbit and eye. It discusses ultrasound, CT, and MR as modalities for evaluating intraocular lesions and complex orbital structures. Ultrasound is recommended as the first-line modality due its non-invasiveness. CT provides excellent evaluation of bone structures and detection of calcifications. MR offers superior soft tissue contrast for evaluating orbital and intracranial structures. Imaging protocols for CT and MR of the orbit and eye are outlined, including recommended sequences, planes of imaging, and use of contrast. Anatomical diagrams illustrate orbital bones and structures visible on different imaging views.

1. ORBIT Imaging anatomy

2. Imaging Recommendations
Radiography
Ultrasound
• First line modality for intraocular lesions
• Noninvasive, readily available
CT & MR are complementary techniques; both are indicated
for evaluation of complex lesions
CT
• Excellent evaluation of orbit aided by natural contrast.
between fat, bone, air & soft tissues.
• Easily detects calcifications.

3. MR
• Optimal soft tissue contrast for globe, optic nerve, orbital
structures, and intracranial findings.
• Stronger gradients, faster sequences, surface coils, routine use
of fat suppression ± gadolinium improve image quality

4. Radiography
WATERS PROJECTION
CM- canthomeatal line; CR- central ray.
(a, frontal sinus; b, medial orbital wall;
c, innominate line; d, inferior orbital rim;
e, orbital floor; f, maxillary antrum;
g, superior orbital fissure; h, zygomatic-frontal suture;
i, zygomatic arch)

5. CALDWELL PROJECTION
a, frontal sinus;
b, innominate line;
c, inferior orbital rim;
d, posterior orbital floor;
e, superior orbital fissure; f, greater wing of sphenoid;
g, ethmoid sinus; h, medial orbital wall;
i, petrous ridge; j, zygomatic-frontal suture

6. LATERAL PROJECTION
a, orbital roof;
b, frontal sinus;
c, ethmoid sinus;
d, anterior clinoid process;
e, sella turcica; f, planum sphenoidale

7. BASAL PROJECTION (SUBMENTO-VERTEX)
a, zygomatic arch;
b, orbit;
c, lateral orbital wall;
d, posterior wall of maxillary sinus;
e, pterygoid plate; f, sphenoid sinus

8. OPTIC FORAMEN (RHESE POSITION)
a, right optic canal;
b, optic strut;
c, superior orbital fissure;
d, ethmoid sinus;
e, planum sphenoidale;
f, greater wing of sphenoid

9. Sonography of eye

10. B-scan probe orientations
1. Axial scan is obtained by placing the probe face directly over
the center of the cornea.
The resulting B-scan image includes the lens and is bisected
by the optic nerve.

14. B-scan probe orientations
2. Longitudinal B-scan require the probe to be placed on the
conjunctiva overlying the sclera and directed through the
vitreous bypassing the lens.
It produce a cross-section of the eye along a specific clock
hour, displaying the anterior portion of the eye at the top of
the screen and the optic nerve at the bottom.

15. Imaging protocols
CT
• Axial + coronal planes; thin-sections (~ 2 mm),Multislice acquisition
• Soft tissue algorithm
• Contrast for masses or inflammatory disease
• Noncontrast only when in conjunction with MR

16. Bones of the Orbit

17. Bones of the Orbit

18. AXIAL BONE CT

21. CORONAL BONE CT

24. MR
• Axial: Above orbital roof to orbital floor
• Coronal: Back of pons through globe
• Thin-section (3-4 mm); small FOV (12-16 cm)
• T1 pre-contrast (axial + coronal)
• STIR or T2 FSE fat-saturation (axial + coronal)
• T1C+ with fat-saturation (axial+coronal)
• Sagittal oblique for optic nerves

28. CORONAL T1 MR

31. OBLIQUE SAGITTAL T1 MR

33. Optic nerve-sheath complex

37. CORONAL &AXIAL STIR MR

39. GLOBE

41. THANK YOU