Flow Imaging in Normal Pressure Hydrocephalus

Flow imaging targeting the cerebral aqueduct has been used in normal pressure hydrocephalus (NPH) to evaluate for imaging features supportive of a clinical diagnosis of NPH and to determine the NPH subtype.^1-3 2D cardiac-gated phase-contrast MRI has been used to evaluate for elevated pulsatile flow through the cerebral aqueduct as one imaging feature supportive of the clinical diagnosis of NPH.^4,5 However, aqueduct flow measurements have a low sensitivity for NPH and are not well correlated with clinical outcomes.^6-9 Structural and flow imaging of the aqueduct is also helpful for differentiating congenital, in some cases obstructive, NPH from idiopathic NPH and determining the appropriate patient management.^10,11 Recent advances in flow imaging in NPH include real-time imaging that allows for evaluation of both cardiac and respiratory contributions to flow and 4D flow imaging to probe flow over a volume (rather than single slice) and provide a more comprehensive assessment of intracranial CSF dynamics.^12-16.