RESEARCH ARTICLE


Quantitative Evaluation of Signal Intensity of Magnetic Resonance Images in Optic Neuritis



Tadao Hanawa1, Atsushi Mizota*, 2
1 Department of Ophthalmology, Chiba Aoba Municipal Hospital, 1273-2 Aoba-cho, Chuoku, Chiba 260-0852, Japan
2 Department of Ophthalmology, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, 279-0021, Japan


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2007 Bentham Science Publishers Ltd.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/) which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the Department of Ophthalmology, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, 279-0021, Japan; Fax: +81-47-355-5949; E-mail: mizota@juntendo-urayasu.jp


Abstract

We have evaluated the signal intensity of magnetic resonance (MR) images of the optic nerve quantitatively in 25 patients with unilateral acute optic neuritis (ON). MR imaging was performed with a 1.5 Tesla unit before treatment within 2 weeks after the onset of ON. Four coronal fat-suppressed T2-weighted images were obtained at 5, 10, 15, and 20 mm behind the eye. The ratio of the signal intensity of the MR images from the optic nerve to that of the white matter of the frontal lobe was calculated and we compared the signal intensity ratio of the affected eyes to the fellow healthy eyes. For statistical analysis paired t-test was used. At all 4 sections, the mean signal intensity ratio of the affected eyes is statistically significant higher than fellow eyes. The 11 patients showed optic disc swelling in the affected eyes and in all these 11 eyes had a higher signal intensity at 5 mm behind the eye compared with the fellow eye. From our present results, we cannot refer to the sensitivity of our method, because we did not use our present methods to other diseases. But with this method we think inter-image and inter-observer variability must reduce. Further studies are required about the sensitivity and the relation between the pathological condition of optic nerve and the signal intensity ratio.