[PS16-2D-1] Neuroimaging of Central Nervous System Infections in childhood
CNS imaging plays an important role in the integrated clinic-radiological diagnosis and management of CNS infections. MRI is more sensitive than CT as it provides excellent contrast between tissues in the brain and spinal cord. Special sequences such as diffusion-weighted and diffusion-tensor-imaging help in differentiation of abscesses from tumours, cerebritis from infarcts, lymphoma from toxoplasmosis and in assessing treatment response. Proton MR-spectroscopy helps in determining the etiology of brain abscesses or intracranial-space-occupying lesions. Gradient-echo based sequences such as CISS help in detection of neurocysticercal lesions in CSF spaces.
Infections such as neurocysticercosis show characteristic imaging appearances according to their pathological stages in the brain. Although all cases of acute bacterial meningitis do not require neuroimaging, suspicion of complications such as ventriculitis, brain abscess, hydrocephalus, empyema and vasculopathy/thrombosis need radiological corroboration.
Specific patterns of brain involvement in encephalitis can give a clue to etiology; involvement of cingulate gyrus, insular and basifrontal cortex are specific for herpes encephalitis, thalamic and substantia nigra involvement is suggestive of Japanese B and West-Nile encephalitis; hyperintensities in basal ganglia and thalami may suggest EBV infection and dorsal brainstem is seen in enterovirus encephalitis. MRI also excludes closely mimicking clinical conditions such as ADEM. Diffusion-weighted imaging is more sensitive for detection of early encephalitis signal changes than conventional MRI.
Thus, neuroimaging plays an important role in the diagnosis and management of CNS infections. Appropriate choice of imaging sequences and techniques in the correct clinical context may corroborate clinical diagnosis and exclude other differentials.
Infections such as neurocysticercosis show characteristic imaging appearances according to their pathological stages in the brain. Although all cases of acute bacterial meningitis do not require neuroimaging, suspicion of complications such as ventriculitis, brain abscess, hydrocephalus, empyema and vasculopathy/thrombosis need radiological corroboration.
Specific patterns of brain involvement in encephalitis can give a clue to etiology; involvement of cingulate gyrus, insular and basifrontal cortex are specific for herpes encephalitis, thalamic and substantia nigra involvement is suggestive of Japanese B and West-Nile encephalitis; hyperintensities in basal ganglia and thalami may suggest EBV infection and dorsal brainstem is seen in enterovirus encephalitis. MRI also excludes closely mimicking clinical conditions such as ADEM. Diffusion-weighted imaging is more sensitive for detection of early encephalitis signal changes than conventional MRI.
Thus, neuroimaging plays an important role in the diagnosis and management of CNS infections. Appropriate choice of imaging sequences and techniques in the correct clinical context may corroborate clinical diagnosis and exclude other differentials.