Diagnostic Accuracy of Contrast-Enhanced T2-FLAIR MRI in diagnosing Infective Meningitis taking CSF analysis as gold standard

Abstract

Objective: To determine the diagnostic accuracy of contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2-FLAIR) MRI in diagnosing infective meningitis, taking cerebrospinal fluid (CSF) analysis as  gold standard.

Methods: In this cross-sectional diagnostic-accuracy study, 142 consecutive adults aged 18-65 years with clinically suspected meningitis underwent 1.5-T brain MRI and CSF analysis. CE-T2-FLAIR was positive when abnormal meningeal enhancement was visible in extra-axial CSF spaces, along superficial brain surfaces, within sulci, or along cranial nerves and cisterns. CSF positivity required pleocytosis of at least 50 cells/µL, protein of at least 40 mg/dL, and a CSF-to-blood glucose ratio of 0.40 or less. Sensitivity, specificity, predictive values, and accuracy were calculated with Wilson 95% confidence intervals.

Results: CSF confirmed infective meningitis in 86/142 participants (60.56%). CE-T2-FLAIR produced 82 true-positive, 10 false-positive, 4 false-negative, and 46 true-negative results. Sensitivity was 95.35% (88.64%-98.18%), specificity 82.14% (70.16%-90.00%), positive predictive value 89.13% (81.14%-93.99%), negative predictive value 92.00% (81.16%-96.85%), and overall accuracy 90.14% (84.13%-94.04%). Accuracy was similar across sex and prespecified age strata.

Conclusion: CE-T2-FLAIR demonstrated high sensitivity and overall diagnostic accuracy for detecting infective meningitis. It can serve as a useful adjunct for recognizing subtle meningeal inflammation and complications, but it should complement rather than replace timely CSF examination and microbiological testing.