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Role
of Magnetic Resonance Imaging (MRI) in the Diagnosis of Secondary
Orbital Tumors
Naglaa Lotfy
Dabees1; Faten M.S1; Mohamed A. El-Disoky2;
Mahmoud Abd El-Aziz D.1 & Dina M.M1
Departments of Radiodiagnosis1 & Ophthalmology2,
Faculty of Medicine, Tanta University, Egypt
Tanta Med. Sc. J 2008; 3(2):3-15
Article type: Original article
Background/Aim: Diagnosis of orbital tumors is
mainly based on indirect ophthalmoscope, but additional imaging
techniques are indispensable for the staging of the disease. MRI is
particularly valuable in assessing the orbital pathway because of
the high degree of sensitivity of fat tissue, changes of hydration
within the soft tissue, and lack of ionizing radiation. Gadolinium
MRI adds to better delineation. CT helps to visualize the bony
involvement better. Purpose of this study was to evaluate the
diagnostic efficiency of Magnetic Resonance Imaging in evaluation of
different orbital lesions, signal behavior on T1-WI, T2WI and T1-WI
before and after contrast application as well as defining tumor
characteristics (i.e. shape, size, position, delineation and
infiltration). Patients & Methods: This study was conducted at the
Radiology and Medical Imaging department of Tanta University
Hospitals on 14 patients. The patients were selected either because
of clinical presentation suggesting for orbital lesions (Proptosis,
loss of vision, retro-orbital pain headache, diplopia, etc) or
lesion in the orbit. Every diagnosis was proved by histopathological
examination or confirmed by other imaging modalities or clinical
course. Results: MRI of both orbits was done for all cases. Standard
orbital MRI protocols should include T1W and T2W axial images, fat
suppressed axial T1W images, and contrast enhanced axial and coronal
T1W images with fat suppression. metastatic and secondary invading
tumors were found in 14 patients; One female with right intraocular
metastasis from cancer breast, one patient with intraorbital
extension from nasopharyngeal carcinoma, 2 patients with
intraorbital extension from cancer ethmoidal and cancer maxillary
sinus, one patient with squamous cell carcinoma of conjunctiva, one
patient with intraorbital extension from primitive neuro-ectodermal
tumor (olfactory neuroblastoma), while secondary orbital meningioma
arising from greater wing of the sphenoidal bone were found in 3
patients; Ocular lesions included 5 patients; One with
retinoblastoma while the other four were malignant melanoma. MRI
gives better characterization of the soft tissue lesions on T1WI,
T2WI and fat saturated images and more information about the
extension of the tumor especially intracranial. In mass lesions
containing hemorrhage or other paramagnetic material (e.g. melanin),
MRI can delineate melanotic melanomas from subretinal fluid
collections and from other choroidal/retinal masses. Conclusion: MRI
is necessary for diagnosis and staging of secondary orbital tumours
involving the orbit from adjacent tissues; paranasal sinus,
nasopharynx, conjunctiva, intraocular tissue, eyelid and
intracranial tissues. Imaging studies should include the orbital
field, sinus and brain to search for the primary. |