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Novel finding of optic nerve central T2 hypointensity utilizing 3 Tesla MR imaging
Roy Riascos1, John C Heymann2, Reza Hakimelahi2
1Department of Diagnostic and Interventional Imaging, The University of Texas in Houston roy.f.riascos@uth.tmc.edu.
The Neuroradiology Journal
|April 30, 2015
Summary
A novel finding of central T2 hypointensity in the optic nerve was observed in all astronauts studied. This previously undescribed MRI finding may represent flow voids from central retinal vessels.
Area of Science:
- Neuroimaging
- Ophthalmology
- Aerospace Medicine
Background:
- Spaceflight is associated with visual changes in astronauts.
- The exact mechanisms behind these visual changes are not fully understood.
- Previous research has focused on intracranial pressure and optic nerve morphology.
Purpose of the Study:
- To report a previously undescribed finding on 3 Tesla (3T) MRI scans of the optic nerve.
- To characterize a central T2 hypointensity within the optic nerve.
- To investigate potential causes for this finding in astronauts.
Main Methods:
- Retrospective analysis of 3T MRI scans of the orbits from 21 astronauts.
- Direct coronal T2-weighted sequences were utilized.
- Scans were obtained between 2010 and 2012 as part of a NASA protocol.
Main Results:
- A central T2 hypointensity was identified in 100% of both right and left eyes.
- The finding was fully visualized in 71.4% of right eyes and 90.5% of left eyes.
- This hypointensity was located in the epicenter of the optic nerve.
Conclusions:
- A consistent, previously unreported central T2 hypointensity exists within the optic nerve in astronauts.
- This finding is present in both eyes of all participants.
- The hypointensity may be attributed to flow voids from central retinal vessels.
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