 |
|
Three-dimensional High-Resolution Magnetic Resonance Imaging of Ocular and Orbital Malignancies
Sharon McCaffery, MD;
Erin M. Simon, MD, OTR;
Nancy J. Fischbein, MD;
Howard A. Rowley, MD;
Ann Shimikawa, MS;
Shan Lin, MD;
Joan M. O'Brien, MD
Arch Ophthalmol. 2002;120:747-754.
ABSTRACT
| |
Background Ultrathin-section 3-dimensional fast spin-echo (3-D FSE) T2-weighted
imaging is a new magnetic resonance imaging (MRI) technique that we used in
the evaluation of ocular and orbital malignancies. We evaluated the usefulness
of this new technique compared with conventional MRI.
Methods Imaging data from 26 consecutive patients seen in the Ocular Oncology
Unit at the University of California–San Francisco were retrospectively
reviewed by physicians from the ocular oncology and neuroradiology units.
For all patients, 3-D FSE T2-weighted images (27
scans) were compared with results of conventional MRI and correlated with
results of computed tomography (CT), A- and B-scan ultrasonography, ultrasound
biomicroscopy, clinical examinations, and histopathology, when available.
Results The 3-D FSE T2-weighted imaging sequence resulted in an overall improvement
in accuracy of imaging findings in 17 (63%) of our 27 cases compared with
the standard MRI protocol. The increased resolution led to the radiographic
detection of additional lesions in 11 (41%) of 27 cases and to an increase
in confidence in radiographic diagnosis in 6 (22%) of the remaining cases.
The improved resolution of the 3-D FSE T2-weighted sequence resulted in a
change of disease management in 3 (60%) of the 5 patients with nonretinoblastoma
lesions. One hundred percent of active retinoblastoma lesions could be detected
by means of 3-D FSE and conventional imaging; however, inactive lesions were
not always detected using conventional imaging.
Conclusions The 3-D FSE T2-weighted sequence offers superior resolution of intraocular
and orbital structures compared with conventional MRI. It is particularly
useful in the evaluation of intraocular tumors and the nerve-sheath complex.
This new technique contributes significantly to improved diagnosis and management
in patients with ocular and orbital malignancies.
INTRODUCTION
NEUROIMAGING in ocular oncology plays an essential role in the accurate
diagnosis of intraocular and orbital tumors. Increased use of globe-conserving
therapies such as external beam radiation, brachytherapy, and chemoreduction
with laser hyperthermia has led to an increased reliance on neuroimaging for
diagnosis and monitoring of disease activity. Patients with intraocular tumors
who have received radiation frequently develop cataracts that preclude visualization
of the retina by indirect ophthalmoscopy. In these patients, we have traditionally
relied on A- and B-scan ultrasonography to follow intraocular tumors. More
recently, high-quality x-ray computed tomography (CT) and magnetic resonance
imaging (MRI) have provided additional, complementary information.
In the management of retinoblastoma (Rb), MRI and CT are superior to
ultrasonography in detecting orbital and optic nerve disease.1
Magnetic resonance or CT imaging is also required for the detection of trilateral
Rb (primitive neuroectodermal tumors, or PNETs) and to define the extent of
secondary orbital, head and neck, and central nervous system (CNS) malignancies.
We routinely obtain thin-section (1 mm) axial unenhanced and enhanced CT scans
for the initial evaluation of suspected Rb. This study provides excellent
detection of intraocular calcification, narrows the differential diagnosis,
and allows us to exclude a synchronous intracranial mass. We also routinely
perform ophthalmic A- and B-scan ultrasonographic studies to document tumor
heights and to further substantiate the presence of intraocular calcification.
In straightforward cases, the initial CT scan is adequate to assess optic
nerve involvement and to exclude CNS disease, although this study is less
sensitive than MRI for these purposes.2-4
In patients with Rb in whom CT or ultrasonographic studies suggest optic
nerve extension of disease, or when superior CNS imaging is mandated by advanced
disease at presentation, we also routinely obtain an MRI scan of the brain
and orbits with contrast. Orbital T2-weighted MRI of the eye with fast spin-echo
(FSE) and surface coils improves image resolution compared with conventional
T2-weighted imaging,5 and this represents the
standard of care at many institutions. Despite this improved resolution, lesions
less than 2 mm thick cannot be recognized with confidence by MRI technology,
even with surface coils.6-7 In
addition, the use of surface coils may impair the assessment of deep but important
adjacent structures such as the orbital apex and the intracanalicular orbital
nerve,8 and surface coils may exacerbate motion
and chemical-shift artifacts.9 Surface coils
require additional time and technologist expertise for proper positioning
and setup. Their use also requires purchase of separate, dedicated coils and
an interruption of the imaging session to transition from surface coil to
head coil for whole-brain imaging, which is indicated in patients with Rb
to exclude concomitant PNETs. Coil placement results in increased anesthesia
time and additional expense for these children.
For these practical reasons, we have focused on improving the quality
of ocular/orbital imaging that can be performed using a standard volumetric
head coil. For T2-weighted imaging, we previously acquired 2-dimensional (2-D)
FSE T2-weighted images in the coronal plane with fat saturation, as fat remains
bright on FSE T2-weighted sequences. Recently, we evaluated an ultrathin-section
3-dimensional (3-D) FSE T2-weighted sequence. This technique uses a modification
of current 3-D FSE imaging by adding another interpolation step during data
processing, which greatly improves spatial resolution. We believe the ability
to obtain submillimeter sections and to reformat this volumetrically acquired
data in 3 dimensions provides superior delineation of intraocular and orbital
tumors and contributes to more accurate diagnosis.
MATERIALS AND METHODS
The managing ocular oncologist (J.M.O.), in collaboration with the neuroradiology
team, retrospectively reviewed 27 thin-section 3-D FSE MRI scans performed
in conjunction with conventional MRI scans from 26 consecutive patients with
known or suspected ophthalmic tumors (Rb, meningioma, choroidal metastasis,
ciliary body melanoma, lymphoma, and lymphangioma). Two neuroradiologists
(E.M.S. and N.J.F.), masked to diagnosis and clinical history, independently
compared the findings on 3-D FSE T2-weighted images with those on conventional
images gathered during the same imaging session.
Conventional MRI, performed in a standard head coil, included orbital
imaging with sagittal, axial, and coronal T1-weighted images; axial and coronal
fat-suppressed 2-D FSE T2-weighted images; and post-gadolinium fat-suppressed
axial and coronal T1-weighted images. Slice thickness was 3 to 4 mm. When
indicated (in all cases with the exception of a ciliary body melanoma and
an orbital lymphangioma), whole-brain sections were added, including axial
dual-echo spin-echo T2-weighted and post-gadolinium axial and sagittal T1-weighted
images.
The thin-section 3-D FSE T2-weighted sequence was also performed in
the head coil, with a typical effective slice thickness of 0.4 mm, matrix
of 256 x 256, and field of view of 18 cm. A fat-suppression pulse was
added without a time penalty. The high resolution was achieved by the addition
of zeros to each end of the data set before performing the Fourier transform
required to produce the images. This zero filling allows for a doubling in
the number of data points that pass through the reconstruction process, thereby
achieving, in effect, twice as many slices from the original volume of data
(Figure 1). The slices are partially
overlapped, which increases the signal-to-noise ratio and provides high-quality
submillimeter slices. This technique is similar to that currently used for
MR angiography.10-11
|
|
|
|
Figure 1. Three-dimensional fast spin-echo
(3-D FSE) T2-weighted image reconstruction. The high resolution of the ultrathin-section
3-D FSE T2-weighted image is achieved by zero-filling interpolation with consequent
overlapping of image location and doubling of data points before the reconstruction
process.
|
|
|
The MRI findings on conventional and 3-D FSE T2-weighted studies were
correlated with results of CT, A- and B-scan ultrasonography, ultrasound biomicroscopy,
clinical examinations, and histopathology, when available. In addition, the
ocular oncologist (J.M.O.) retrospectively assessed the impact of the 3-D
FSE T2-weighted findings on patient management.
RESULTS
The 3-D FSE T2-weighted sequence resulted in an overall improvement
in accuracy of findings in 17 (63%) of our 27 cases (Table 1). The increased resolution led to the radiographic detection
of additional lesions in 11 (41%) of our 27 studies. These additional lesions
usually represented previously treated sites of Rb in regression (Figure 2); however, the confirmation of a
second contralateral lesion in a patient with a non-Rb lesion that was not
visualized by clinical examination or conventional imaging led to a change
in management (Table 1; bilateral
metastatic adenocarcinoma).
|
|
|
|
Contribution of 3-D FSE T2-Weighted Imaging*
|
|
|
|
|
|
|
Figure 2. Pre-treatment and post-treatment
appearance of retinoblastoma (Rb). T1-weighted post-gadolinium image with
fat suppression (A) and 3-dimensional fast spin-echo (3-D FSE) T2-weighted
image (B). The 3-D FSE T2-weighted image shows untreated retinal tumors bilaterally
(arrows). The right lesion could not be detected on the post-gadolinium T1-weighted
image. T1-weighted post-gadolinium image with fat suppression (C) and 3-D
FSE T2-weighted image (D) after left enucleation and placement of a hydroxyapatite
implant. The treated disease in the right globe was subtle (arrow) and was
identified only by means of the 3-D FSE T2-weighted scan. Pre-treatment (E)
and post-treatment (F) appearance of Rb on indirect ophthalmoscopy.
|
|
|
Of the remaining cases, the neuroradiologists noted an increased confidence
in anatomic detail and lesion conspicuity in 6 scans (22%), which resulted
in a change in management in 2 of these cases (Table 1; lymphangioma and orbital lymphoma). Overall, management
was changed in 3 (60%) of 5 non-Rb cases. Of the active Rb lesions, 100% could
be detected by means of 3-D FSE T2-weighted and conventional imaging; however,
inactive lesions were not always detected using conventional imaging. No change
in radiographic diagnosis or confidence resulted in 10 (37%) of the 27 scans.
Superior resolution compared with conventional imaging sequences was achieved
in all but 2 scans, in which motion degradation occurred in 2 awake adults.
Specifically, 3-D FSE T2-weighted scanning was superior to more traditional
MRI in the following respects:
- Increased resolution of normal intraocular structures
and intraocular tumors was evident, particularly for those tumors that were
small, low-lying, or previously treated. This finding had particular clinical
importance in this series in patients with media opacities due to cataract
or vitreous hemorrhage, in which indirect ophthalmoscopy was less sensitive.
These studies provided verification of findings obtained on A- and B-scan
ultrasonography.
- Increased resolution and improved delineation of the optic nerve–dural
sheath complex and associated cerebrospinal fluid space, as well as of normal
orbital structures, were found. For example, after enucleation, atrophic optic
nerves were extremely well delineated, with 3-D FSE T2-weighted imaging demonstrating
decreased nerve size, increased nerve signal, and prominence of the surrounding
cerebrospinal fluid space. Although no patients with extraocular extension
confirmed by histopathology were part of this study, our experience suggests
that the 3-D FSE sequence with fat saturation has the potential to improve
resolution of optic nerve extension in patients with Rb. This imaging approach
also allowed better characterization of orbital tumors compared with conventional
MRI.
- The 3-D data set offers the opportunity to perform multiplanar
reformations of data with no stair-step artifacts or penalty in terms of resolution.
- Improved resolution of intracranial structures was achieved, compared
with conventional 2-D FSE T2-weighted images.
We found a few limitations of 3-D FSE T2-weighted imaging compared with
conventional imaging that should be noted. First, 3-D FSE imaging is more
susceptible to motion, phase, and pulsation artifacts. Second, 3-D FSE imaging
involves a longer acquisition time (9-11 minutes) compared with conventional
2-D FSE imaging (4-5 minutes). Both sequences are compatible with and should
be performed with fat saturation. Third, less coverage can be achieved in
a reasonable duration when 3-D FSE is used compared with 2-D FSE. Therefore,
for example, the pineal region was not included on all of our 3-D FSE studies.
In all patients, conventional MRI of the pineal region was completed.
COMMENT
The 3-D FSE T2-weighted sequence offers a new approach to ocular and
orbital MRI that uses ultrathin slices to achieve superior image resolution.
The potential to perform multiplanar reformations to assist in clinical interpretation
is a unique feature of this technique that may contribute to the superior
assessment of intraocular and orbital structures. The 3-D FSE technique provides
improved resolution compared with conventional head-coil 2-D FSE T2-weighted
imaging with fat saturation without a requirement for surface coils. We expect
this technique could be easily implemented by other centers.
RETINOBLASTOMA
Because of the increasing use of eye-conserving treatments, neuroimaging
has assumed greater importance in the management of Rb in children.12 In many cases, histopathologic examination is never
performed.12 Neuroimaging is therefore important
in the initial diagnosis and staging of the disease as well as in the continued
care and follow-up of these patients, who are subject to multiple intraocular
recurrences throughout the first 6 years of life.13
Second primary tumors, PNETs within the CNS, also develop at an early age
in up to 10% of patients with bilateral Rb,14-17
and a recent description of successful treatment for trilateral disease suggests
that screening with improved detection is of increasing importance.18 Older children are subject to additional second tumors,
primarily sarcomas within the orbital radiation field.13-14
The use of free flaps after orbital exenteration for these disease processes
makes improved resolution imperative to diagnose subclinical disease recurrence.19
Although A- and B-scan ultrasonography plays an important role in the
management of intraocular Rb,20-21
the presence of massive intraocular calcification can impede visualization
of the optic nerve and orbit, making evaluation of these structures more difficult.22 In these cases, it is essential to obtain additional
information through the use of neuroimaging. To confirm the initial diagnosis,
we obtain a CT scan for documentation of intraocular calcification. For subsequent
evaluations, we believe that MRI is useful to exclude optic nerve disease,
to evaluate for orbital and intracranial extension, and to exclude the possibility
of PNETs. We follow children with low-stage Rb routinely every 6 months with
MRI, including 3-D FSE T2-weighted imaging, and we believe this technique
reliably surveys for the development of PNETs. Children with high-stage disease
at presentation are followed more frequently with neuroimaging to evaluate
the optic nerve and orbit and to assess the CNS for relapse.
Three-dimensional FSE T2-weighted technology is particularly useful
in the evaluation of intraocular tumors in patients with opaque media limiting
indirect ophthalmoscopy. This is especially important in children treated
with external beam radiation, because cataracts almost invariably develop
in these patients (Figure 3). In
the setting of cataract, ultrasonography is required to visualize tumors,
to evaluate for tumor growth, and to assess tumor activity. We find that 3-D
FSE T2-weighted MRI very accurately evaluates tumor size and is useful as
an adjunct to ultrasonographic measurements in patients with massive disease
at presentation and extensive calcification, which is highly reflective and
results in shadowing of the orbit and optic nerve.
|
|
|
|
Figure 3. Retinoblastoma (Rb) with radiation-associated
cataract. A, A dense posterior subcapsular cataract obscures the view on indirect
ophthalmoscopy. B, B-scan ultrasonogram confirms a mass in the left eye. C,
A small enhancing focus of treated Rb can be seen in the left globe with the
fat-suppressed T1-weighted post-gadolinium sequence (arrow). A very subtle
lesion in the right eye was seen only by comparison with the 3-dimensional
fast spin-echo (3-D FSE) image. Lens morphology and the signal are abnormal
bilaterally. D, The 3-D FSE T2-weighted sequence allows clear identification
of a lesion in each globe (arrows).
|
|
|
Magnetic resonance imaging is most useful in children with advanced
Rb, in which optic nerve and orbital extension significantly affect treatment
planning and prognosis.12, 22 We
presently perform preenucleation chemoreduction in patients with orbital extension
to avoid exenteration. After 2 to 3 cycles of chemoreduction, we repeat neuroimaging
studies and perform orbital biopsies.
The increased resolution of intraocular structures with 3-D compared
with 2-D FSE T2-weighted imaging has the potential to improve diagnosis of
choroidal invasion and optic nerve extension. Optic nerve extension and massive
choroidal invasion are associated with significant morbidity and mortality.12, 22 This technique, then, has immediate
clinical implications for those patients who are candidates for ocular conservation,
as they may require adjuvant chemotherapy for increased survival.12 No patients with histopathologically confirmed risk
factors were available to include in this series, limiting our certainty that
these processes can be reliably diagnosed by any currently available imaging
technique.
Despite its superior resolution compared with conventional 2-D FSE T2-weighted
imaging, 3-D FSE T2-weighted imaging does not necessarily provide a clear
advantage in the evaluation of intracranial structures. This is largely due
to the relatively limited anatomic coverage available when using standard
scan times. We generally rely most heavily on post-gadolinium T1-weighted
sequences to detect intracranial extension, metastatic foci, and trilateral
disease.
PERSISTENT HYPERPLASTIC PRIMARY VITREOUS
In patients referred with leukocoria, the possibility that the child
has a lesion that can mimic Rb, such as persistent hyperplastic primary vitreous
(PHPV) or Coats' disease, should receive serious consideration in the initial
diagnosis and management.6 Intraocular biopsy
is contraindicated in children with a potential diagnosis of Rb because of
the possibility that the tumor can spread along the needle track,23 and because increased mortality is associated with
extraocular disease.12 These children must,
therefore, undergo evaluation using indirect diagnostic approaches. In this
series, a patient with bilateral PHPV and dystrophic calcification was followed
using A- and B-scan ultrasonography and 3-D FSE MRI. A subretinal hemorrhage
that evolved over time was documented. The 3-D FSE data increased our confidence
in the diagnosis of PHPV, as the persistent tunica vasculosa lentis was well
defined, the globes were confirmed to be small, and no mass developed over
serial observation (Figure 4).
|
|
|
|
Figure 4. Persistent hyperplastic primary
vitreous (PHPV). A, Pre-gadolinium T1-weighted scan demonstrates bilateral
microphthalmia and bilateral retinal detachments with hemorrhagic or proteinaceous
fluid (intrinsically bright on the T1-weighted scan). B, Three-dimensional
fast spin-echo (3-D FSE) T2-weighted scan clearly shows the right retrolental
mass and the bilaterally persistent tunica vasculosa lentis. C, The bilateral
retinal detachments are again seen on 3-D FSE T2-weighted imaging with differences
in the signal intensity attributable to variations in protein content.
|
|
|
OTHER NEOPLASMS
Any ocular oncology service will evaluate many patients with other neoplasms,
including choroidal melanoma, choroidal metastases, meningiomas of the optic
nerve, and a variety of orbital masses. In this series, we obtained useful
information in patients with non-Rb intraocular and orbital malignancies.
Superior resolution of these lesions enhanced our ability to make accurate
diagnoses and to provide immediate treatment planning.
For example, in an elderly man, the MRI appearance of a right lateral
orbital mass, associated with proptosis and medial displacement of the right
lateral rectus and superior rectus, was most compatible with lymphoma (Figure 5). The increased confidence in anatomic
detail provided by 3-D FSE T2-weighted imaging favored this diagnosis and
demonstrated that CT-guided needle biopsy could be safely performed. The patient,
who was in poor health, was spared an open surgical orbital biopsy, and treatment
was expedited.
|
|
|
|
Figure 5. Lymphoma. A, Marked proptosis
in an elderly man who had a right lateral orbital mass at initial examination.
B. An enhancing mass is seen superficial to and medially deviating from the
right lateral rectus (arrow) using fat-suppressed T1-weighted post-gadolinium
imaging. C, Three-dimensional fast spin-echo T2-weighted image shows improved
tumor resolution (arrow).
|
|
|
In addition, 3-D FSE T2-weighted data changed the management of a right
orbital mass in a child. Improved visualization of a cystic mass with internal
septations and fluid-fluid levels only apparent on 3-D FSE T2-weighted findings
favored a diagnosis of a venolymphatic malformation and obviated the need
for open biopsy (Figure 6).
|
|
|
|
Figure 6. Probable venolymphatic malformation.
A, An enhancing soft tissue mass in the right medial orbit (arrow) is seen
on this post-gadolinium T1-weighted image with fat suppression. B, The mass
is much more conspicuous, and the margins are better defined (arrow) on the
3-dimensional fast spin-echo T2-weighted scan. The lesion is multilobulated
and multilocular, showing areas of variable T2-weighted signal intensity consistent
with a lymphatic malformation. The variable signal intensity is a result of
blood breakdown products of varying ages producing heterogeneity in protein
concentration.
|
|
|
Finally, 3-D FSE T2-weighted imaging confirmed an additional lesion
in the contralateral eye of a patient who was thought to have metastatic disease
rather than a primary process, eg, a hemorrhagic retinal detachment or melanoma.
Indirect ophthalmoscopy was limited in the second eye by a dense cataract,
an inability to dilate, and patient disability. The detection of bilateral
disease favored a metastatic process and led to a search for a primary lesion.
A CT-guided biopsy of an abdominal mass on the day of presentation subsequently
led to the diagnosis of metastatic adenocarcinoma of an unknown primary lesion
and expedited ocular radiation therapy.
The 3-D FSE T2-weighted technique was comparable to conventional imaging
in the evaluation of a ciliary body melanoma. The pigmented mass was not well
resolved by 3-D FSE T2-weighted imaging, conventional MRI, or A- and B-scan
ultrasonography. However, ultrasound biomicroscopy accurately demonstrated
the melanoma in the ciliary body (Figure 7). The efficacy of ultrasound biomicroscopy for the resolution of
tumor margins in ciliary body and anterior uveal melanoma is supported by
a recent study at our institution24 and is
an additional tool for the evaluation of potentially subtle anterior intraocular
masses.
|
|
|
|
Figure 7. Ciliary body melanoma. A, High-resolution
slitlamp photograph of a pigmented mass involving the right iris. B, A mass
was not recognized on a post-gadolinium T1-weighted scan, or C, a 3-dimensional
fast spin-echo (3-D FSE) T2-weighted scan performed through the level of the
ciliary body (arrow). However, after ultrasound biomicroscopy, the mass could
be defined on the 3-D FSE T2-weighted image only. D, The ciliary body melanoma
is accurately demonstrated only by ultrasound biomicroscopy.
|
|
|
CONCLUSIONS
This initial retrospective review of 3-D FSE T2-weighted technology
suggests that this MRI sequence provides significant additional information
to the treating ophthalmologist in patients with intraocular and orbital malignancies.
This technology provides information that is not currently available by means
of ultrasonography or CT scanning, as well as providing improved information
compared with conventional MRI sequences. We believe that 3-D FSE T2-weighted
technology represents a significant step forward in the diagnosis and management
of such tumors, particularly with the increasing use of eye-conserving measures.
AUTHOR INFORMATION
Submitted for publication August 15, 2001; final revision received February
25, 2002; accepted February 28, 2002.
This study was supported in part by a Physician Scientist Award from
Research to Prevent Blindness, Inc, New York, NY; That Man May See Foundation,
Inc, San Francisco, Calif; The Sand Hill Foundation, Inc, San Mateo, Calif;
and core grant EY02162 from the National Eye Institute, Bethesda, Md (University
of California–San Francisco Department of Ophthalmology).
We thank Tony Tsai, MD, and Erin Browne for their assistance with the
figures.
Corresponding author: Joan M. O'Brien, MD, Department of Ophthalmology,
Beckman Vision Center, Ocular Oncology Division, University of California–San
Francisco, 10 Koret Way, Room K-301, Box 0730, San Francisco, CA 94143-0730.
From the Departments of Ophthalmology (Drs McCaffery, Lin, and O'Brien)
and Radiology (Drs Simon, Fischbein, and Rowley), University of California–San
Francisco; and General Electric Medical Systems, Milwaukee, Wis (Ms Shimikawa).
Dr Simon is now affiliated with The Children's Hospital of Philadelphia, Philadelphia,
Pa; Dr Rowley, Department of Radiology, University of Wisconsin Medical School,
Madison.
REFERENCES
| |
1. Dorfman RE, Spickler EM. Current status of magnetic resonance imaging of the orbit. Top Magn Reson Imaging. 1990;2:17-26.
2. Barnes PD, Robson CD, Robertson RL, Poussaint TY. Pediatric orbital and visual pathway lesions. Neuroimaging Clin N Am. 1996;6:179-198.
PUBMED
3. Mafee MF, Goldberg MF, Cohen SB, et al. Magnetic resonance imaging versus computed tomography of leukocoric
eyes and use of in vitro proton magnetic resonance spectropscopy of retinoblastoma. Ophthalmology. 1989;96:965-976.
ISI
| PUBMED
4. Maya MM, Heier LA. Orbital CT: current use in the MR era. Neuroimaging Clin N Am. 1998;8:651-683.
PUBMED
5. Hosten N, Lemke AJ, Bornfeld N, et al. Fast spin-echo MR imaging of the eye. Eur Radiol. 1996;6:900-903.
PUBMED
6. Kaufman LM, Mafee MF, Song CD. Retinoblastoma and simulating lesions: role of CT, MR imaging and use
of Gd-DTPA contrast enhancement. Radiol Clin North Am. 1998;36:1101-1117.
FULL TEXT
| PUBMED
7. Wycliffe ND, Mafee MF. Magnetic resonance imaging in ocular pathology. Top Magn Reson Imaging. 1999;10:384-400.
PUBMED
8. Ettl A, Salomonowitz E, Koornneef L, Zonneveld FW. High-resolution MR imaging anatomy of the orbit: correlation with comparative
cryosectional anatomy. Radiol Clin North Am. 1998;36:1021-1045.
PUBMED
9. Atlas SW. Magnetic resonance imaging of the orbit: current status. Magn Reson Q. 1989;5:39-96.
PUBMED
10. Du YP, Parker DL, Davis WL, Cao G. Reduction of partial-volume artifacts with zero-filled interpolation
in three-dimensional MR angiography. J Magn Reson Imaging. 1994;4:733-741.
ISI
| PUBMED
11. Parker DL, Du YP, Davis WL. The voxel sensitivity function in Fourier transform imaging: applications
to magnetic resonance angiography. Magn Reson Med. 1995;33:156-162.
ISI
| PUBMED
12. Uusitalo MS, Van Quill KR, Scott IU, Matthay KK, Murray TG, O'Brien JM. Evaluation of chemoprophylaxis in patients with unilateral retinoblastoma
with high-risk features on histopathologic examination. Arch Ophthalmol. 2001;119:41-48.
FREE FULL TEXT
13. Cassady JR. Radiation therapy and chemotherapy for retinoblastoma: current status. In: Albert DM, Jakobiec FA, eds. Principles and
Practice of Ophthalmology. 2nd ed. Philadelphia, Pa: WB Saunders Co;
2000:5102-5116.
14. Uusitalo M, Wheeler S, O'Brien JM. New approaches in the clinical management of retinoblastoma. Ophthalmol Clin North Am. 1999;12:255-264.
15. Duncan JL, Scott IU, Murray TG, Gombos DS, Van Quill KR, O'Brien JM. Routine neuroimaging in retinoblastoma for the detection of intracranial
tumors. Arch Ophthalmol. 2001;119:450-452.
FREE FULL TEXT
16. De Potter P, Shields CL, Shields JA. Clinical variations of trilateral retinoblastoma: a report of 13 cases. J Pediatr Ophthalmol Strabismus. 1994;31:26-31.
ISI
| PUBMED
17. Blach LE, McCormick B, Abramson DH, Ellsworth RM. Trilateral retinoblastoma—incidence and outcome: a decade of
experience. Int J Radiat Oncol Biol Phys. 1994;29:729-733.
ISI
| PUBMED
18. Bindlish R, LaRoche GR. Successful treatment of neonatal trilateral retinoblastoma. J AAPOS. 1999;3:376-378.
19. Uusitalo M, Ibarra M, Fulton L, et al. Reconstruction with rectus abdominis myocutaneous free flap after orbital
exenteration in children. Arch Ophthalmol. 2001;119:1705-1709.
FREE FULL TEXT
20. Zilelioglu G, Gunduz K. Ultrasonic findings in intraocular retinoblastoma and correlation with
histopathologic diagnosis. Int Ophthalmol. 1995;19:71-75.
PUBMED
21. Byrne SF, Green RL. Ultrasound of the Eye and Orbit. St Louis, Mo: Mosby–Year Book Inc; 1992:197-200.
22. Shields CA, Shields JA, Baez K, Carter JR, De Potter P. Optic nerve invasion of retinoblastoma: metastatic potential and clinical
risk factors. Cancer. 1994;73:692-698.
FULL TEXT
| PUBMED
23. Karcioglu ZA, Gordon RA, Karcioglu GL. Tumor seeding in ocular fine needle aspiration biopsy. Ophthalmology. 1985;92:1763-1767.
ISI
| PUBMED
24. Daftari I, Barash D, Lin S, O'Brien JM. Use of high-frequency ultrasound imaging to improve delineation of
anterior uveal melanoma for proton irradiation. Phys Med Biol. 2001;46:579-590.
PUBMED
RELATED ARTICLE
Archives of Ophthalmology Reader's Choice: Continuing Medical Education
Arch Ophthalmol. 2002;120(6):876-877.
FULL TEXT
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
Pre- and Posttreatment MR Imaging in AIDS-Related Kaposi Sarcoma of the Conjunctiva and Lacrimal Gland
Scheschonka et al.
Am. J. Neuroradiol. 2003;24:1327-1329.
ABSTRACT
| FULL TEXT
|
