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.
Highlights
The usefulness of magnetic resonance (MR) imaging in the diagnosis of optic neuritis (ON) was described as early as 1987 by Johnson et al [1] using short time inversion recovery (STIR) sequences
We have investigated quantitatively the signal intensity of the MR images of the optic nerve at several points along the optic nerve in eyes with optic neuritis to determine the effectiveness of MRI in diagnosing and assessing optic neuritis
The MR images of a 22-year-old patient with acute unilateral optic neuritis are shown in Fig. (2)
Summary
The usefulness of magnetic resonance (MR) imaging in the diagnosis of optic neuritis (ON) was described as early as 1987 by Johnson et al [1] using short time inversion recovery (STIR) sequences. In 1998, Jackson and his co-workers [7] studied the signal intensities in comparison to that of white matter and a combination of increased signal intensity and swelling in patients with ON and classified findings of optic nerve into 4 grades, grade 0 to 3. This normalization was used to remove the effects of inter-image and inter-observer variability. The purpose of their study was to examine the benefits of combined fat- and water-suppressed T2-weighted MRI for the diagnosis of optic neuritis
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