Type:
Educational Exhibit
Keywords:
Eyes, Anatomy, Oncology, CT, MR, Education, Diagnostic procedure, Staging, Metastases, Multidisciplinary cancer care
Authors:
C. E. Desaga; Cluj Napoca/RO
DOI:
10.1594/ecr2018/C-2855
Background
The orbit and visual system represent a complex and intricately organized region,
with specialized anatomy and physiology.
A variety of diseases determine space-occupying lesions in this region.
These include congenital,
vascular,
inflammatory and infectious disease,
as well as benign and malignant neoplasms.
Cross-sectional imaging is essential in the diagnosis and evaluation of orbital neoplasms,
supplementing findings from fundoscopy and clinical ophthalmologic examinations.
CT is considered convenient because of the natural contrast provided by the adjacent structures with widely different attenuation coefficients like fat,
bone,
fluid,
muscle or adjacent air and is preferred over MRI for detecting small calcifications (as is the case in an optic nerve meningioma or a retinoblastoma) and assessment of the bony orbit and also because of MRI sensitivity to lid and globe motion.
However,
MRI is gaining more acceptance because of its greater sensitivity in characterizing diseases of the orbit,
involved orbital compartments,
spread to the orbital apex or along perineural pathways and superior ability to detect concomitant intracranial abnormalities.
MRI is considered superior for evaluating the orbital apex and intracanalicular lesions.
The various anatomical subdivisions within the orbit are conveniently clustered into several anatomical areas or compartments for the purpose of imaging interpretation and differential diagnosis: the globe and the intraconal,
conal and extraconal compartments.