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.