4. Imaging of intraconal lesions
Slice thickness
Resolution of a CT depends on slice thickness.
The thinner the slice, the higher the resolution.
2mm cuts are optimal for the eye and orbit.
In evaluation of the orbital apex, thinner slices of
1mm can be more informative.
5. Tissue
window
Soft-tissue window is best for evaluating orbital soft tissue
lesions.
Fractures and bony details are better seen with bone window
settings .
6. MRI with Fat-suppressed
images
Bright signal from intraorbital fat can mask the
signal and enhancement of pathology.
This problem can be overcome by suppressing
the signal of fat by special fat suppression
sequences.
7. Common intraconal tumors
1. Optic nerve lesions:
a. Optic nerve glioma.
b. Optic nerve sheath meningioma.
2. Well-defined intraconal tumors:
a. Cavernous hemangioma.
b. Schwannoma.
c. Solitary neurofibroma.
d. Hemangiopericytoma.
e. Fibrous histocytoma.
3. ILL-defined intraconal tumors:
a. Lymphoma.
b. Lymphangioma.
c. Metastasis.
8. Optic nerve glioma
* 80% less than 10 years, M less than F .Uncommon and sporadic
in adult
* Malignant gliomas (glioblastoma) are rare & almost always occur
in adult males with a very poor prognosis.
* Associated with NF1 in 50-85% of childern
* low grade spindle shaped pilocytic (hair like) astrocytes & glial
filaments
* Slowly progressive drop of V/A and slowly progressive proptosis
* CT: fusiform enlargement of the optic nerve, enhancing , may
extend to optic tract
9. Optic nerve lesions
Optic nerve has a blood-brain barrier
So, normally No enhancement
Optic nerve enhancement:
. Normal caliber Neuritis
.Enlarged optic nerve Glioma
. Outside optic nerve Meningioma
10. fusiform enlargement with sharp delineation from the surrounding
tissue .They are isodense, with enhancement with contrast
11. Appearance of optic nerve gliomas:
(a)In a patient without neurofibromatosis
(b)In a patient with neurofibromatosis
A B
12. T2 imaging in a similar coronal
plane reveals hyperintense
signaling of the mass that is
contained within the dura of the
optic nerve.
This axial, post-contrast MRI
demonstrates enhancement of
the fusiform, kinked shaped
optic nerve tumor.
18. Optic nerve sheath meningioma
A benign tumor arising from arachnoid cells
lining the dura.
Presents 10-30% of orbital meningioma,
however, majority of cases from intracranial
extension.
Middle age females are more affected.
If present in childhood it is more aggressive.
Mostly sporadic, if associated with NF2 may
be bilateral.
.
Slowly progressive drop of V/A and proptosis
19. Optic nerve sheath meningioma
They tend to be hyperdense to the optic
nerve,
More consistent contrast enhancement.
Calcification within the optic nerve
shadow
CT and MR imaging;
Prominent focal or segmental enlargement of
the dural arachnoid sheath around the optic
nerve .
24. Cavernous Hemangioma
Most common benign tumor of the orbit.
Peak between 20-40 years.
Slowly growing proptosis.
Hamartomas contained within a fibrous capsule with
large vascular channels, but no definite feeding
vessels.
They are almost always intraconal (80%).
Well defined mass and may enlarge with a Valsalva
maneuvre or during pregnancy
25. CT and MR imaging:
May be located anywhere in the orbit occur
within the retrobulbar muscle cone.
Uncommonly, an intramuscular
hemangioma may occur.
Well-defined masses.
Variable contrast enhancement.
Always respect the contour of the globe.
Orbital bone modeling is not uncommon.
29. Hemangiopericytoma
. 1-3% of all biopsied orbital lesions.
. Mostly superior in the orbit but may be
intraconal.
. Highly vascular with marked
enhancement.
. Proliferation of pericytes and stg-
horn.
30. Schwannoma
Arising from schwan cells of any nerve within
the orbit – most common V1.
Account for 1-6% of all orbital masses.
Slow growing, well circumscribed, ovoid
with homogenous enhancement.
The optic nerve is always displaced.
31. Well-defined mass , hyperintense on T2-weighted
images and enhance. Similar to cavernous
hemangioma.
On dynamic scanning cavernous hemangiomas
begin with a central spot of enhancement,
which spreads peripherally.
Whereas, orbital schwannomas usually enhance
initially on the periphery.
Both may remodel adjacent bone.
33. Neurofibroma
Neurofibromas is a benign tumor originating
from Schwann cells that occur in the orbit
as isolated lesions or in association with
plexiform neurofibromatosis.
Differs from schwannoma in
. Invade the adjacent nerve
. Contain fibrous tissue in addition to schwann
cells
. Soft uncapsulated
Malignant peripheral nerve tumors (malignant
schwannoma, neurofibrosarcoma) are
extremely rare in the orbit.
34. Neurofibroma
◦
A, Postcontrast axial CT scan demonstrating a well-enhanced intraconal neurofibroma .
◦
◦
B, Axial T1WI scan of a neurofibroma A. Tumor is isointense to brain and hypointense to orbital fat.
◦
◦
C, Axial fat-suppressed T1-weighted MR image of the tumor with marked contrast enhancement of
neurofibroma.
38. Fibrous histiocytoma
. Most common primary mesenchymal orbital
tumor in adults.
. Malignant transformation may occur
. Orbital radiation may cause malignant
transformation.
. Mixture of fibroblasts and histiocytes
39. lymphoma
Lymphoproliferative disease includes a
spectrum of disorders ranging from benign
(lymphoid hyperplasia) to malignant
disease (lymphoma).
Immunohistochemical and molecular
biological studies have been reliable to
differentiate these entities.
more commonly in the 5th–7th decades of life
with a slight female predominance.
.
Intraconal space is involved in 11%
40.
41. Staging
National Cancer
Institute Working Formulation of
Non-Hodgkin’s Lymphomas
Low-Grade Lymphomas
Small lymphocytic
Follicular, predominantly small cleaved cell
Follicular, mixed, small cleaved cell and large
cell
Intermediate-Grade Lymphomas
Follicular, predominantly large cell
Diffuse, mixed, small and large cell
Diffuse, large cell (cleaved and noncleaved)
High-Grade Lymphomas
Diffuse large cell, immunoblastic
Lymphoblastic (convoluted and non-convoluted)
Small noncleaved cell (Burkitt’s and
non-Burkitt’s)
42. Revised European-American Classification of Lymphoid
Neoplasms (REAL)
Indolent Lymphomas
Follicular lymphoma
B-chronic lymphocytic leukemia/small
lymphocytic lymphoma
Lymphoplasmacytic lymphoma
Marginal zone lymphoma (nodal, extranodal,
splenic)
T-cell/natural killer large cell granular
lymphocyte leukemia
T-chronic lymphocytic leukemia/
prolymphocytic leukemia
Aggressive Lymphomas
Mantle cell lymphoma
Diffuse large B-cell lymphoma
Peripheral T-cell lymphoma (unspecified)
Peripheral T-cell lymphoma (angioimmunoblastic,
angiocentric)
T-cell/natural killer cell, hepatosplenic,
intestinal T-cell lymphoma
Anaplastic large cell lymphoma
Highly Aggressive Lymphomas
Precursor T or B lymphoblastic leukemia/
lymphoma
Burkitt’s and Burkitt’s-like lymphoma
Adult T-cell leukemia/lymphoma
43. Imaging of lymphoma
A mass with distinct margins, which shows an
isointense signal on T1-weighted images and
iso-hyperintense on T2-weighted images.
Spiral computed tomography (CT) using a dual-
phase contrast-enhancement protocol report
that lymphomas have a decrease in density on
delayed images, as opposed to orbital
pseudotumours, whose density increases on
delayed images
44. CT imaging:
On non-contrast CT, the mass is usually homogeneous in
density, either isodense or slightly hyperdense when
compared to the extraocular muscles .
mild to moderate enhancement is seen, similar again to the
extraocular muscles
47. The origin of lymphangioma = controversial.
The lesion is unencapsulated.
Consisting mostly of bloodless vascular and lymph
channels.
lymphangioma( venous lymphatic
malformation)
48. Worsening of proptosis when the child has an upper
respiratory tract infection.
Either continuous with the venous circulation or
associated with an arteriovenous malformation
Spontaneous or traumatic hemorrhage within the
lesion is common, resulting in a chocolate cyst.
Typically diffuse and not well encapsulated
Usually multilobular.
49. CT:
Poorly circumscribed, heterogeneous masses of increased
density. Bony remodeling may be present. Calcification is
rare. Minimal contrast enhancement may be present
MRI:
Relatively hypointense or hyperintense to brain on T1WI.
Very hyperintense on T2WI. Fluid-fluid levels related to
hemorrhages of various ages are characteristic of
lymphangioma.
Axial CT with left orbital
lymphangioma
Axial CT with left choclate cyst
51. Metastasis to the Orbit
Accounts for approximately 10% of all orbital neoplasms.
(5% hematogenous, 5% from adjacent structures).
What is the most common tumor to spread to
the orbit?
Breast Cancer (42%).
Lung Carcinoma (11%).
Unknown Primary Cancer (11%).
Prostate (8%).
Melanoma (5%). Average survival after dx is 9 months.
52. Bilateral orbital metastases from a carcinoma of the breast.
Axial postcontrast CT demonstrates a homogeneous mass in the retrobulbar
space of the left orbit.
