Objective: To determine the diagnostic values of Contrast-Enhanced 3D Fluid-Attenuated Inversion Recovery with Fat Suppression (CE-3D FLAIR/FS), Contrast-Enhanced 3D Spoiled Gradient-Echo High Resolution T1-Weighted (CE-3D THRIVE), and Contrast-Enhanced T1-Weighted Images (CE-T1WI) in the diagnosis of infectious leptomeningitis, and if they correlated with the cerebrospinal fluid (CSF) analysis.

Materials and Methods: Fifty-six patients with clinical suspicion of infectious leptomeningitis and referred for magnetic resonance imaging (MRI) of the brain between January 2016 and December 2017 were enrolled before starting treatment. Twenty-one were diagnosed with infectious leptomeningitis, proven by CSF culture/profile, abnormal CSF cytology, or biochemical marker, and 35 had normal CSF analysis. CE-3D FLAIR/FS, CE-3D THRIVE, and CE-T1WI sequences of all patients were reviewed separately by two neuroradiologists and were determined as positive or negative for leptomeningeal enhancement or subarachnoid space abnormality. Diagnostic accuracy of each sequence was calculated and compared.

Results: The CE-3D FLAIR/FS sequence showed 100% sensitivity, 88.6% specificity, 84.0% positive predictive value (PPV), 100% negative predictive value (NPV), and 92.9% accuracy. CE-3D THRIVE revealed 76.2% sensitivity, 94.3% specificity, 88.9% PPV, 86.8% NPV, and 87.5% accuracy. CE-T1WI demonstrated 100% sensitivity, 85.7% specificity, 80.7% PPV, 100% NPV, and 91.1% accuracy. The CE-3D FLAIR/FS sequence showed the best visualization of leptomeningeal enhancement in cranial nerves (80.95%, p=0.001), followed by CE-3D THRIVE sequence (42.86%) and CE-T1WI sequence (23.81%). Nonetheless, the CE-T1WI showed statistically significant differences in detecting leptomeningeal enhancement along cerebral sulci, cerebellar folia, and cisterns compared to CE-3D FLAIR/FS and CE-3D THRIVE (p=0.012, 0.001, and 0.003).

Conclusion: All CE-3D FLAIR/FS, CE-3D THRIVE, and CE-T1WI MR sequences had high diagnostic accuracy for detection of infectious leptomeningitis without statistically significant difference. The present study showed the highest diagnostic performance on CE-3D FLAIR/FS sequence, followed by CE-T1WI and CE-3D THRIVE sequences in detecting infectious leptomeningitis. The 3D volume data in CE-3D FLAIR/FS and CE-3D THRIVE sequences was helpful to evaluate leptomeningeal enhancement along the cranial nerves.

Keywords: Infectious leptomeningitis, Leptomeningeal enhancement, Subarachnoid space abnormality, CE-3D FLAIR/FS, CE-3D THRIVE, CE-T1WI

Received 12 Dec 2019 | Revised 24 Feb 2020 | Accepted 25 Feb 2020