Diagnostic performance of contrast-enhanced T2-FLAIR MRI in the detection of meningitis

Background: The contrast-enhanced T2-FLAIR (CE-T2-FLAIR) sequence on MRI, through the suppression of CSF and vascular signals, can detect subtle meningeal enhancement in meningitis that may not be appreciable on the routinely used contrast-enhanced T1W (CE-T1W) sequence. Objectives: To assess CE-T2-FLAIR compared to CE-T1W in the diagnosis of meningitis, using CSF analysis as the gold standard, using both qualitative and quantitative approaches for assessment. Method: A retrospective study was conducted on 53 patients with clinically suspected meningitis referred for brain MRI. Twenty-seven patients, positive for meningitis on CSF analysis, were classified as the case group; the remaining patients were designated as controls. The pre-contrast, CE-T1W and CE-T2-FLAIR images were assessed and analysed, qualitatively for the detection of abnormal meningeal enhancement, and quantitatively by measuring single pixel signal intensities (SPSI) over the meninges and vessels. Results: Contrast-enhanced T2-FLAIR demonstrated significantly higher sensitivity (92.59% vs. 57.69%), negative predictive value (92.59% vs. 70.27%) and diagnostic accuracy (94.34% vs. 78.85%) compared to CE-T1W. Additionally, CE-T2-FLAIR showed significantly greater meningeal SPSI and enhancement than CE-T1W. Conclusion: Contrast-enhanced T2-FLAIR is better at detecting abnormal meningeal enhancement in meningitis than CE-T1W, because of significantly greater signal intensity and enhancement of the meninges compared to vessels. Contribution: This study reiterates the usefulness of CE-T2-FLAIR as an additional sequence for the detection of abnormal meningeal enhancement in cases of meningitis as confirmed both qualitatively and quantitatively.