Use of magnetic resonance imaging to differentiate optic neuritis and nonarteritic anterior ischemic optic neuropathy.
OBJECTIVE
To determine if magnetic resonance imaging (MRI) of the optic nerves obtained during the acute phase can distinguish patients with optic neuritis (ON) from those with nonarteritic anterior ischemic optic neuropathy (NAION).


METHODS
Retrospective, neuroradiologic, observational study.


METHODS
Sixty-four patients diagnosed as having either ON or NAION who were diagnosed by clinical criteria and imaged by MRI.


METHODS
Demographic information on the MRI scans was masked and the patients were presented randomly and in a blinded fashion to a neuroradiologist (JDR) for determination of abnormalities. Reproducibility was assessed by presenting 10 of the scans a second time to the same neuroradiologist.


METHODS
The presence or absence and location of abnormal MRI signals of the optic nerve.


RESULTS
Evaluation of reproducibility revealed identical interpretations of the ten scans submitted a second time. The optic nerve was abnormal in the clinically affected eye in 31 of the 32 ON patients but in only 5 of the 32 NAION patients. Thirty of the 31 ON patients who received gadolinium had enhancement, and 27 of the 32 ON patients had increased short T(1) inversion recovery signal in the clinically affected optic nerve. The five NAION patients with abnormal scans in the clinically affected eye had increased short T(1) inversion recovery signal, and in two of these, there also was enhancement of the optic nerve. For the ON patients, enhancement involved the entire length of the intraorbital optic nerve in 18 cases and the intracranial segment of the optic nerve in 19 cases.


CONCLUSIONS
Our study shows that MRI scanning of the optic nerve shows significantly different results between patients clinically diagnosed with either ON or NAION.
Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA. Joseph_Rizzo@meei.harvard.edu
Joseph F
JF
Rizzo
Christopher M
CM
Andreoli
James D
JD
Rabinov
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001167:Arteritis / Q000175:diagnosis; D001706:Biopsy; D003937:Diagnosis, Differential; D004311:Double-Blind Method; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000473:pathology; D009902:Optic Neuritis / Q000175:diagnosis*; D018917:Optic Neuropathy, Ischemic / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013699:Temporal Arteries / Q000473:pathology