Region and phase-specific diffusion tensor imaging dynamics in Japanese encephalitis: A linear mixed-effects analysis

BackgroundJapanese encephalitis (JE) is a mosquito-borne disease caused by a flavivirus and responsible for significant morbidity and mortality. Asymmetrical deep nuclei involvement is the characteristic Magnetic Resonance Imaging finding. However, it fails to highlight the evolution of microstructural alteration throughout the disease progression. The study aims to describe the longitudinal, stage-specific evolution of diffusion tensor imaging parameters in JE.MethodsThis was a retrospective study of 72 serologically established JE patients, determining microstructural alteration in JE in acute (≤7 days) and subacute (8-30 days) phases. The DTI values for ADC, MD, FA, RD, and AD were extracted from bilateral thalami and basal ganglia. The longitudinal changes of the DTI values were determined using linear mixed-effects models with phase, region, and phase × region interaction as fixed effects.ResultsThe most frequent involvement was the thalami compared to the basal ganglia on conventional MRI. Mixed-model effects analysis revealed significant phase-related increases in ADC and MD, while FA and RD demonstrated strong region-specific temporal effects. Significant phase × region interactions were detected for ADC, FA, RD, and AD, suggesting greater temporal variability in the thalamus than the basal ganglia. Post hoc testing confirmed a marked discrepancy between acute and subacute stages, particularly in the thalamus.ConclusionDTI reveals dynamic, region-dependent microstructural evolution in JE. The thalamus is showing the most distinct changes over time. These findings suggest that DTI may provide complementary information regarding disease activity and may be considered a potential imaging marker of disease evolution.