05 was considered statistically significant. The pair-wise κ for each pair or readers with similar experience levels (the pair of radiology residents, the pair of neuroradiology fellows, etc.) was also compared using the Cohen and weighted κ. Interobserver reliability was computed using a model-based measure of agreement, which is robust to the underlying disease prevalence, 26 and 95% confidence intervals were obtained from 1000 bootstrapped samples. Improvements in diagnostic performances in cases versus controls were compared between the baseline and processed image within a group using a McNemar test. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated for each reader and were also averaged for all readers. The median of the ratings across all readers was identified for both baseline and processed images, and the difference in the median (processed-baseline image) was computed and compared using a paired t test or signed rank test, to assess improvement in the confidence of categorizing the optic nerve using signal intensity and enhancement. A paired t test or a signed rank test was used to evaluate differences between baseline and processed images in the optic nerve and control groups. Continuous variables were summarized using means and SDs and median (25th percentile, 75th percentile). 24, 25 The objective of this study was to test whether image processing of existing MR imaging scans with CIE can be used to improve detection of optic neuritis by selectively improving the CNR of diseased optic nerves.ĭescriptive statistics were used to summarize the imaging metrics. 23 It has been previously shown to improve the contrast-to-noise ratio (CNR) between diseased and normal brain tissue in brain infarction and mesial temporal sclerosis. 22 Improving the conspicuity of optic nerve abnormalities on MR imaging may help improve the detection of optic neuritis, particularly to minimize the need for intravenous contrast, detect subclinical disease, or improve the sensitivity in communities where scans are interpreted by general radiologists.Ĭorrelative image enhancement (CIE) is a proprietary image postprocessing algorithm based on the correlative properties of contiguous pixels designed to increase the conspicuity of details of interest on existing CT and MR imaging scans. Despite these challenges, some previous studies have reported sensitivities in the detection of optic neuritis by neuroradiologists ranging from 75.7% on noncontrast MR imaging 21 to 94% on contrast-enhanced MR imaging. 20 However, the lack of proximity of the optic nerve to the white matter and different intensities of surrounding structures make this comparison difficult. 13 – 19 The optic nerve signal is best compared with normal white matter in the brain. 7 In addition, with increasing recognition of subclinical optic neuropathy in patients with multiple sclerosis, 12 the use of MR imaging to detect optic neuritis–related nerve abnormalities might become even more important.Ĭhallenges of MR imaging of the optic nerve include its small size, heterogeneity of the surrounding orbital tissue, and artifacts related to eye movements or the presence of surrounding orbital fat. 11 MR imaging can help solidify the clinical diagnosis, especially in atypical cases. 1, 2, 5 – 10 While the diagnosis can often be made clinically, misdiagnosis is common, reported in almost 60% of referrals in 1 study. 1, 3 – 5 It presents with changes in visual acuity, eye pain, a relative afferent pupillary defect, and sometimes optic disc swelling. Optic neuritis is an acute-to-subacute, demyelinating optic neuropathy, typically occurring in young women 1, 2 in association with multiple sclerosis.

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