Table 4 Measurement items for the analysis of orbital diseases on imaging.
| Â | Measurements |
|---|---|
Extraocular muscles | Inferior rectus muscle enlargement (> 6.5 mm) |
Medial rectus muscle enlargement (> 5.1 mm) | |
Lateral rectus muscle enlargement (> 4.1 mm) | |
Superior rectus muscle complex enlargement (> 5.2 mm) | |
Superior oblique muscle enlargement (> 3.2 mm) | |
Fatty infiltration of extraocular muscles | |
Lacrimal gland | Lacrimal gland enlargement |
Orbital fat | Excess orbital fat |
Orbital fat stranding | |
Orbital apex and optic nerve | Orbital apex fat effacement grading 0 none; 1 (1–25%); 2 (25–50%); 3 (> 50%) |
Retrobulbar optic nerve sheath complex (> 7.1 mm) | |
Waist portion of optic nerve sheath complex (> 5.4 mm) | |
Proptosis | CT-based exophthalmometry using lateral to medial orbital rims-corneal surface in the axial plane |
Superior ophthalmic vein | Superior ophthalmic vein enlargement (> 2 mm axial or > 3 mm coronal) |
Trigeminal nerve | Infraorbital nerve enlargement (> 2.0 mm) |
Any trigeminal nerve involvement; comment | |
Sinus | Ipsilateral/adjacent involved sinus disease 0 = none; 1 = trace; 2 = trace to 25%, 3 = 25–50%; 4 =  > 50% |
Signal characteristics | Enhancement pattern |
Signal intensity on T2-weighted images on magnetic resonance images |
