Details of CT and MRI

1. CT and MRI in orbital and optic
nerve pathology
Dr Diwa Hamal Lamichhane
III rd year resident

2. Layout
 History
 Introduction
 Normal CT and MRI scans
 CT and MRI scans in some orbital and optic nerve
pathologies

3. History MRI scan
 The first successful nuclear magnetic resonance (NMR) experiment was made in
1946 independently by two scientists in the United States. Felix Bloch, working at
Stanford University, and Edward Purcell, from Harvard University

4. Introduction - MRI scan
 when certain nuclei were placed in a magnetic field they absorbed energy in
radiofrequency range of electromagnetic spectrum & re-emitted this energy when
nuclei transferred to their original state.
 "Nuclear" as only nuclei of certain atoms reacted in that way
"Magnetic" as a magnetic field was required
"Resonance" because of the direct frequency dependence of magnetic
and radiofrequency fields.
 For this discovery Bloch and Purcell were awarded the Nobel Prize
for Physics in 1952.

5. How does MRI scan work???
 Created by placing the patient in a strong magnetic field (approx 30,000× stronger
than earth's magnetic field).
 This affects nuclei within field, specifically nuclei of elements with odd numbers of
protons or neutrons eg. H2 which is plentiful in H20 & fat.
 These nuclei, which are essentially protons, possess a quantum spin. When
patient's tissues are subjected to this strong magnetic field, protons align
themselves with respect to the field.

7. How does MRI scan work ????
 All imaging is performed within this constant magnetic force, this becomes the
steady state, or equilibrium. In this steady state, a radiofrequency pulse is applied,
which excites the magnetized protons in the field and perturbs the steady state.
 After application of this pulse, a receiver coil or antenna listens for an emitted
radiofrequency signal that is generated as these excited protons relax or return to
equilibrium.
 This signal, with the help of localizing gradient fields and Fourier transformation,
creates the MRI image

8. History - CT scan
 CT or CAT (computed axial tomography) derives its meaning from the Greek
words tomos meaning "slice" or "section", and graphia meaning "describing".
 CT imaging was invented by two independent researchers: Sir Godfrey Hounsfiled
of EMI laboratories, England, and a physicist by the name of Dr. Allan Cormack
 The two researchers developed the first CT scanners solely used for brain
imaging between the years of 1974 and 1976.
 Hounsfield and Cormack later received the Nobel Prize for their contributions to
medicine.

9. The Human Brain from Siretom CT scanner circa 1975 (Left),
Human Brain from modern CT scanner (Right)

10. How does CT scan it work ???
 Computerized axial tomography (CAT) scanning, is a medical imaging procedure
that uses x-rays to show cross-sectional images of body.
 Produces cross-sectional images or "slices" of areas of the body, like the slices in
a loaf of bread, used for a variety of diagnostic & therapeutic purposes
 A motorized table moves patient through a circular opening in CT imaging system.
While the patient is inside the opening of the CT imaging system, an x-ray source
and detector within the housing rotate around the patient.

11. How does CT scan it work ???
 A single rotation takes about 1 second. The x-ray
source produces a narrow, fan-shaped beam of x-rays that passes through a
section of the patient's body.
 A detector opposite from the x-ray source records the x-rays passing through the
patient's body as a "snapshot" image. Many different "snapshots" (at many angles
through the patient) are collected during one complete rotation.
 For each rotation of the x-ray source and detector, the image data are sent to a
computer to reconstruct all of the individual "snapshots" into one or multiple cross-
sectional images (slices) of the internal organs and tissues.

12. Complications - MRI
 Physical injury in presence of ferromagnetic FB because of
movement within the strong magnetic field.
 Unusual burns reported in patients using ECG leads & pulse
oximeter during MRI.

13. Complications – CT scan
 lifetime risk of cancer due to x-ray radiation exposure.
 Possible allergic reactions or kidney failure due to contrast agent, or “dye”
 Rare - prolonged, high-dose exposure x-rays can cause skin reddening
(erythema), skin tissue injury, hair loss, cataracts, and potentially, birth defects (if
scanning is done during pregnancy).
 Greater risk for children because they are more sensitive to radiation using the
same parameters as those used on an adult, an unnecessarily large dose will be
delivered to the child.

14. Choice of imaging according to suspected pathology
 Vascular lesions : T1 w, provide the best anatomic details of the
orbit
 Neural lesions : MRI
 Metastatic tumors : MRI
 Intraocular tumors : MRI, to differentiate uveal melanomas from
other primary & secondary intraocular tumors as well as choroidal
detachments.

15.  Trauma : Soft tissue – MRI, Craniofacial bony trauma - CT
 Cystic lesions : T1 w
 Muscle lesions : Equally well with CT and MRI
 Osseous lesions : CT
 Retinoblastoma calcification easily detected by CT & ocular USG but
not MRI
Contd…

16. Checklist for CT
 Orbits – Symmetrical, Normal size, Normal orbital cone
 Orbital walls - Smooth, sharp borders
 No bone destruction
 No circumscribed widening of bone or soft tissue components
 Globe - Position
 Symmetry
 Size
 Spherical
 Ocular contents - Density
 Ocular wall - Borders (smooth and sharp)
 Uniform thickness

17. Checklist for CT
 Optic nerve –
 Caliber, Course
 Eye muscles
 Position
 Width
 Course
 Retrobulbar fat
 Clear, No masse
 Ophthalmic vein
 Course
 Caliber
 Lacrimal gland
 Size
 Symmetry
 No unilateral or bilateral enlargement
 Position
 No excavation or destruction of
adjacent bone
 Homogeneous internal structure
 No hypodense areas
 Smooth borders

18. Important Data in CT
1. Diameter of globe:
Axial plane:
Right: 28.6 ± 1.2 mm
Left: 29.4 ± 1.4 mm
Sagittal plane (reconstruction):
Right: 27.8 ± 1.2 mm
Left: 28.2 ± 1.2 mm
2. Position of globe:
Posterior margin is 9.9 mm ± 1.7
mm behind the interzygomatic line

19. Important Data in CT
3. Optic nerve (axial plane):
a Retrobulbar segment: 5.5 mm ± 0.8
mm
b Narrowest point (at approxinately mid-
orbit): 4.2 mm ± 0.6 mm ± 1 mm
(coronal plane)

20. Important Data in CT
4. Ophthalmic vein:
1.8 mm ± 0.5 mm (axial plane, 4 mm
slice thickness) 2.7 mm

21. Important Data in CT
5. Eye muscles:
a Superior rectus: 3.8 mm ± 0.7 mm
b Oblique: 2.4 mm ± 0.4 mm
c Lateral rectus: 2.9 mm ± 0.6 mm
d Medial rectus: 4.1 mm ± 0.5 mm
e Inferior rectus: 4.9 mm ± 0.8 mm

22. Important Data in CT
 Lacrimal gland:
less than half of the gland is anterior to the frontozygomatic
process.

23. Checklist in MRI
 Orbit
 Shape (orbital cone)
 Size
 Symmetry
 Orbital walls:
 Borders (smooth and sharp)
 No bone destruction
 No circumscribed expansion of
bony or soft tissue
 Components of the orbital wall
 Globe
 Shape (spherical)
 Size
 Position
 Symmetry

24. Checklist in MRI
 Ocular contents:
 Signal intensity (fluid-equivalent)
 Ocular wall:
 Borders (smooth and sharp)
 Thickness
 Retrobulbar fat (clear)
 No masses
 Optic nerve
 Caliber
 Course
 Eye muscles
 Position
 Width
 Course

25. Checklist in MRI
 Ophthalmic vein
 Course
 Caliber
 Lacrimal gland
 Size
 Symmetry
 No unilateral or bilateral enlargement
 Position
 No excavation or destruction of adjacent bone
 Homogeneous internal structure
 No hypointense or hyperintense changes
 Smooth borders

26. Important Data in MRI
1 Diameter of globe:
a Axial image plane: right 28.6 ± 1.2 mm
left 29.4 ± 1.4 mm
b Sagittal image plane: right 27.8 ± 1.2
mm Left 28.2 ± 1.2 mm
2 Position of globe:
Posterior margin of globe is 9.9 mm ±
1.7 mm behind interzygomatic line

27. Important Data in MRI
3 Optic nerve (axial image plane):
a Retrobulbar segment: 5.5 mm ± 0.8
mm
b Narrowest point (at approximately mid-
orbit): 4.2 mm ± 0.6 mm

28. Important Data in MRI
4 Eye muscles:
a Lateral rectus: 2.9 mm ± 0.6 mm
b Medial rectus: 4.1 mm ± 0.5 mm
c Superior rectus: 3.8 mm ± 0.7 mm
d Oblique: 2.4 mm ± 0.4 mm
e Inferior rectus: 4.9 mm ± 0.8 mm
f Levator palpebrae superioris: 1.75 mm
± 0.25 mm

29. Important Data
5 Ophthalmic vein:
a 1.8 mm ± 0.5 mm (axial image, 4 mm
slice thickness)
b 2.7 mm ± 1 mm (coronal image)
6 Lacrimal gland:
Less than one-half of the gland
is anterior to the frontozygomatic
Process Sagittal image

30. Important Data in MRI

31. T1 - Weighted image T2 - Weighted image

32. Proton-density image
Fat suppression reducing the
normal bright signal of orbital
fat in T1-weighted images

33. Fluid-attenuated inversion recovery (FLAIR).

34. Axial Contrast enhanced CT
o= optic nerve sheath
complex
l= lateral rectus
lg= lacrimal gland
m= medial rectus
e= ethmoid sinus
s= sphenoid sinus
cs= cavernous sinus
b= basilar artery
t= tentorium

35. Axial CT - orbital apex & optic canal.

36. T1-weighted magnetic resonance imaging.

37. Axial images at the level of superior orbit. T1-weighted magnetic
resonance imaging.

39. Coronal images through cavernous sinus and optic chiasm T1-weighted
magnetic resonance imaging through anterior chiasm

41. CT and MRI
in orbital pathology

42. T2/FSE axial (MRI) of a 5-month-old
girl with unilateral
anophthalmos(clinically).
normal orbital anatomy and normal
brain
Axial T2-weighted, MRI of a 7-year-old
boy with bilateral microphthalmos,marked
mental retardation and epilepsy. Normal
brain anatomy

43. Unilateral retinoblastoma.
Axial CECT -right intraocular mass with a large chunk of calcification.
There is no evidence of retrobulbar spread
A 2-year-old boy presenting with leukokoria RE

44. Retinoblastoma with intracranial extension.
Axial CECT reveals a left intraocular mass with multiple foci of calcification
with extension along the optic nerve (a) to the suprasellar area (b)
A 30 months child presented with proptosis and leucokoria LE

45. Retinoblastoma.
MRI - left intraocular mass which is isointense on T1W (a) and markedly
hypointense on T2W (b) images showing moderate contrast enhancement (c)
Male child with h/o leucokoria LE

46. 2 year-old-girl presenting with leukokoria of the right eye.
Axial contrast enhanced CT: visualization
of specific partial calcification of the tumor
of the right globe.
T2-weighted view with an irregular
hypointense mass of the posterior right
globe
Retinoblastoma

47. Axial CT: small globe with calcification of the lens and a part of the globe
55 yrs male with blind eye for last many yrs
Phthisis bulbi of the right globe.

48. Orbital calcifications:
 Retinoblastoma (>50 % of intraorbital calcifications)
 Vascular malformations or old hemorrhage
 Optic nerve head drusen
 Phthisis bulbi
 Retrolental fibroplasia
 Meningioma
 Scleral calcification in hypercalcemic states
 Foreign bodies
 Parasitic: Cysticercosis
 Teratoma etc.

49. A 9-month-old girl with swollen left lid and febrile state.
lid abscess with impending orbital cellulitis
Axial contrast-enhanced CT with protrusion of the left globe, inflammatory
infiltration of the left lid, and slight extraconal postseptal infiltration between
the lateral orbit wall and the lateral rectus muscle (arrow)

50. 52-year-old man with a h/o a painful, red, bulging right eye
with blurring and double vision for 2 weeks
Orbital
Cellulitis
Orbital CT Axial, showing periorbital soft tissue swelling, thickening of the
posterior sclera, and proptosis OD

51. A 59-year-old woman with progressive visual deficit of the left eye.
Corresponding IR image providing
a more conclusive delineation of the
pathologic process
uveal melanoma
T1-weighted, contrast-enhanced view
outlining the tumor, which apparently
originates in the lateral ciliary body;
additional retinal detachment in the
posterior part

52. T1- weighted, contrast-enhanced (FS)
image showing the small, irregular, but
extensive choroidal tumor, located
lateral to the macula
Corresponding T2-weighted image with
signal change to hypointensity
53 yrs lady with progressive diminution of vision LE
Choroidal melanoma

53. A 73-year-old woman with known malignant melanoma LE
T2-weighted (FS) view of the inferior
orbit with irregular hypointense mass in
the posterior circumference of the left
globe and medial extraocular
retrobulbar space
T1-weighted view, demonstrating the
hyperintense signal of the melanoma,
apparently with extra ocular extension
medially
malignant melanoma with intraorbital expansion.

54. 35-year man with acute visual loss -right eye with known Behçet disease..
Axial T1-weighted view with subacute vitreous
hemorrhage of the RE
with a comparison with the normal signal of
the left globe indicates the presence of
choroidal effusion characterized by signal
diminution at the posterior part of the globe
T2-weighted proton density image with
demarcation of the fluid by signal
enhancement of the proton-containing fluid
VH of RE and choroidal effusion

55. A 47-year woman with chronic pulmonary sarcoidosis, presenting with acute uveitis.
Axial T2-weighted (FS) image
demonstrating thickening of the
choroid bilateral to the optic nerve.
Axial T1-weighted native (FS) scan
showing primarily hyperintense infiltration
at the same site.
uveal granuloma in sarcoidosis

56. retroocular granuloma in sarcoidosis
After i.v. gadolinium,
Additional extra- and retro-
ocular granuloma, sparing
the sclera, can be identified
by enhancement
Contd…

57. Young adult who sustained a road traffic accident
Coronal CECT shows the fracture in the orbital floor with entrapped inferior rectus
muscle
Orbital blow out fracture

58. Orbital trauma
Blow out fractures
( Post. Medial portion
of the maxillary bone)
Coronal view in bone window with typical sign
of a “hanging drop”, and accompanying
hematosinus of the maxillary sinus

59. A 33-year-old man who suffered an accident
Axial view of the inferior orbit
demonstrates the location of the foreign
body as retrobulbar in the intraconal
area.
Coronal view in bone window with
definition of the foreign body in the
inferior and lateral intraconal area
perforation LE with intraorbital foreign body

60. 2-year-old boy with orbital contusion caused by an exploding bottle
Axial view; although no foreign body is
detectable, an air bubble at the level of
the lens of the left eye can be identified.
sagital view with caudal dislocation of the
lens
Traumatic dislocation of the lens

61. 8 yrs girl presented with gradual proptosis and diminution of vision RE (a)
Middle aged lady presented with marked proptosis and diminution of
vision LE (b)
CECT (a) shows moderately enhancing diffuse tubular thickening of the right
intraorbital optic nerve.
(b )There is marked fusiform enlargement of the left optic nerve causing anterior
displacement of the globe
Optic nerve glioma.

62. optic nerve sheath meningioma.
T1weighted, contrast-enhanced axial MRI shows diffuse enlargement and
enhancement along the length of the left intraorbital (IO) and intracanalicular
(IC) optic nerve sheath Note the tram track appearance

63. Optic nerve sheath glioma Vs meningioma
Features Glioma Meningioma
1. Age Children (2-6years) Middle aged (females)
2. Appearance Fusiform/ tubular
enlargement of optic
nerve
Eccentric lesion/
enlargement of the nerve
sheath
3. Calcification Rare Common
4. Enhancement Rare Intense, homogeneous/
Tram track enhancement
(thickened meningeal
sheath separated by
CSF).
5. Intracranial extension Common (optic chiasma
& hypothalamus)
Uncommon
6. Association NF 1 NF 2

64. 61-year woman- slowly progressiive right axial proptosis with a slowly progressive
visual deficit.
Axial medial orbital view, showing a clearly
defined intraconal mass, sparing the apex.
Coronal view
Neurinoma (schwanoma)

65. 32-year-old man with h/o double vision
Axial view with a sharply defined, tumor-
like mass in the right superior medial
orbit
Coronal view showing additional
involvement of the superior oblique
muscle.
lymphoma of the right superior oblique muscle

66. A 2-month-old girl with divergent strabismus and progressive proptosis of the right eye.
Axial contrast-enhanced view, showing
proptosis of the right globe, enlargement of
the medial rectus muscle,.
coronal, more frontal view showing the
growth “embracing” the posterior region of
the globe
juvenile capillary hemangioma

67. 46-year-old man with slowly progressing hyperopia and proptosis of the RE
Axial T1-weighted native view,
showing a well-encapsulated, sharply
defined intraconal tumor, pressing on
the posterior lateral part of the globe
T1-weighted, contrast-enhanced view at
the level of the optic nerve with more
clearly defined intraconal localization
lateral to the optic nerve
cavernous hemangioma

68. Cavernous hemangiomas
A homogenous well-defined intraconal mass is seen in the left orbit
which is isointense on T1W (a), hyperintense on T2W sequence (b) and
reveals heterogeneous enhancement (c).

69. 43-year woman with oropharynx carcinoma presenting in a febrile state with acute N III
paresis and left-sided protopsis.
Axial CECT: Enlarged, sharply defined
structures with central low density at the level of
the optic nerve. The lesions are intraconal,
extraconal, as well as preseptal, (Note
enhancement of both ICA in the hypodense,
nonenhancing, but thrombosed cavernous sinus.
Involvement of superior ophthalmic vein
in the superior part of the orbit,
-sparing the normal intravascular
contrast
cavernous sinus thrombosis

70. A teenage boy presents
to emergency room with
headache and cranial
nerve palsies.
Coronal T1 MRI with contrast (on day of admission)
showing left cavernous sinus enlargement and
thickening.
Cavernous
sinus
thrombosis

71. 48-year-old woman with slowly progressing, bilateral proptosis associated with bruit.
CT: Axial contrast enhanced
image with bilateral dilation of
the superior ophthalmic vein
carotid-cavernous fistula (CCF)

72. 54-year-old man with painless blurred vision with progressive proptosis chemosis and
bruit over the right orbit.
carotid-cavernous fistula
Axial view showing dilated superior ophthalmic vein

73. Graves’ ophthalmopathy:
Axial CECT showing thickening of medial and lateral recti
muscles involving bellies. Note characteristic sparing of
tendons and globe
40 yrs female presented with b/l proptosis

74. A 73-year-old woman with bilateral exophthalmos. :
Axial view -severe thickening of all external
rectus muscles, excluding the tendinous
insertion. marked compression of both optic
nerves at the apex
Coronal view
Graves’ disease

75. 49-year-old woman with b/l proptosis
Axial CT -severe thickening of the medial rectus
muscles, more pronounced on the right side,
Axial view of the medial orbit, where
demonstrating bilateral severe
proptosis
Graves’ ophthalmopathy:

76. A 4-year-old girl with progressing proptosis of the right eye
The CECT - enhancement of all
structures of the right orbit: the sclera,
rectus muscles, as well as the orbital
fat
Diffuse scleral thickening of the entire
circumference, distinct, hazy hyperdensity of
the retrobulbar fat, diffuse swelling of the
lateral rectus muscle, including the
tendinous insertion
Orbital pseudotumor

77. Orbital pseudotumor
(a)Axial CECT - a diffuse infiltrative right orbital mass involving the globe and causing
marked proptosis.
(b) Diffuse oblong enlargement of the lacrimal gland with preservation of its shape.
(c) diffuse thickening of the bilateral medial and lateral recti including their tendons
proptosis contd…..

78. Orbital pseudotumor.
Gross mass-like enlargement of the medial rectus muscle, with characteristic
hypointense signal on T1W (a) and T2W (b)
Moderate heterogeneous enhancement is seen in the post gadolinium image
(c)
Contd…

79. Graves’ Ophthalmopathy & Orbital
Pseudotumor
Features Graves’ Pseudotumor
1. Extent of
involvement
Enlargement of
extraocular muscles
(common), infiltration
of retro-orbital fat
(less common)
Involvement of
extraocular muscles,
lacrimal apparatus,
sclera, optic nerve
sheath, lid, fat &
diffuse involvement
2. Extraocular
muscle involvement
Only bellies involved,
tendons spared
Bellies as well as
tendons involved
3. Scleral thickening Absent Present
4. Order of
involvement
I M S L No specific order

80. A 25-year-old man, presenting with unspecified pressure of the left orbit persisting for
several months and a recent onset of double vision.
Axial T2-weighted view with a
hyperintense, well-delineated, cystic
structure of the left middle ethmoid
region.
T1-weighted image, demonstrating pressure
exerted on the periorbit and medial rectus muscle.
mucocele of the left ethmoid.

81. coronal CT with characteristic
biconvex configuration of the ethmoid cell and thinned
bony cortex (small white arrows)
Contd…
mucocele of the
left ethmoid.

82. A 86-year-old woman with a long history of nonaxial proptosis of the left eye.
Axial CECT with a predominantly solid, partly
calcified, partly cystic encapsulated tumor of
the left extraconal space, and significant
depression and flattening of the anterior
dislocated globe.
Corresponding T1-weighted, contrast-
enhanced view with more distinct
differentiation of the capsule and the
cystic tumor parts
Pleomorphic adenoma of the lacrimal gland.

83. Adult male with h/o sudden painlless diminution of vision LE over 1 week
MRI shows bright spots on the right optic nerve
Optic
neuritis LE

84. 72 year male patient
recently admitted for
fatigue and hyponatremia
who complains of
progressively worsening
vision in both eyes over
the past few years
There is pallor of the left
optic nerve
Pituitary adenoma

85. Pituitary adenoma

86. grows at the base of the brain and arises from the band of
tissue connecting the brain and the pituitary gland
Craniopharyngioma
h/o progressive visual field deficit

87. Advances in Technology and Clinical
Practice
 Today most CT systems are capable of "spiral" (also called "helical") scanning as
well as scanning in the formerly more conventional "axial" mode. In addition, many
CT systems are capable of imaging multiple slices simultaneously. Such advances
allow relatively larger volumes of anatomy to be imaged in relatively less time.
 EBCT- the principle of creating cross-sectional images is the same as for
conventional CT, whether single- or multi-slice, the EBCT scanner does not
require any moving parts to generate the individual "snapshots." As a result, the
EBCT scanner allows a quicker image acquisition than conventional CT scanners

88. Other techniques -
 Contrast CT scan
 3D CT
 CT angiography
 CT venography
 Spiral and helical CT
 MRI with gadolinium
enhancement
 Fat suppression techniques
 T1 fat saturation
 STIR (short T1 inversion
recovery)
 FLAIR (Fluid attenuation
inversion recovery)
 MR angiography
 MR venography

89. Thank you

90. Width of ophthalmic vein
 MRI  CT
4. 3−4 mm

91. Optic nerve (axial image)
5a. Retrobulbar segment: 5.5 mm ± 0.8 mm
5b. Narrowest point (at approximately mid-orbit): 4.2 mm ± 0.6 mm
 MRI  CT

92. Position of globe
 MRI  CT
6. Posterior margin of globe 9.9 mm ± 1.7 mm behind interzygomatic line

93. Size of EOM
 MRI  CT

94. Diameter of the globe
 MRI  CT
Axial plane:Right: 28.6 ± 1.2 mm,Left: 29.4 ± 1.4 mm
Sagittal plane (reconstruction):Right: 27.8 ± 1.2 mm, Left: 28.2 ± 1.2 mm

95. Lacrimal gland
 MRI  CT
less than half of the gland is anterior to the frontozygomatic process

96.  Configuration of orbital cone
 Contents
 Globe (position, size, density, wall thickness)
 Eye muscles (position, course, density, width)
 Optic nerve (course, width)
 Ophthalmic vein (course, width)
Orbit - CT

97. Orbit in CT
 The orbits are symmetrical and of normal size, with normal development of the
orbital cone. The configuration of the smooth, sharply defined orbital walls is
normal. There are no foci of bone destruction and there is no circumscribed
widening of bony or soft-tissue components of the orbital walls. The globes are
symmetrical and show normal size and position. The ocular contents are of normal
density. The ocular wall is smooth, sharply defined, and of normal thickness. The
optic nerve shows a normal course and caliber on each side. The eye muscles are
normally positioned and display normal width and course. The retrobulbar fat and
ophthalmic vein are unremarkable. Imaged portions of the neurocranium and
paranasal sinuses show no abnormalities.

98. Interpretation of CT
 The orbit and its contents appear normal

99. MRI
Orbit
 Configuration of orbital cone
 Contents:
 Globe (position, size, signal intensity, wall thickness)
 Eye muscles (position, course, signal intensity, width)
 Optic nerve (course, width)
 Ophthalmic vein (course, width)

100. Orbit in MRI
 The orbits are symmetrical and of normal size, with normal development the
orbital cones. The orbital walls shows normal configuration with smooth, sharp
margins. No foci of bone destruction, no circumscribed expansion of the bony or
soft-tissue components of the orbital wall are evident.
 The globes are symmetrical and of normal size and position, and the ocular
contents show normal signal characteristics. The ocular walls are smooth, sharply
defined, and of normal thickness. The optic nerve has normal course and caliber
on each side.
 The eye muscles are normally positioned and display normal course and width.
The retrobulbar fat, ophthalmic vein, and lacrimal gland are unremarkable.

101. Interpretation
 The orbits and orbital contents appear normal.