The purpose of this project is to assess the utility of a new magnetic resonance technique called magnetic resonance elastography (MRE) in the non-invasive diagnosis of normal pressure hydrocephalus. The investigators hypothesize that MRE produces a unique imaging signature for hydrocephalus that distinguishes the disease from the normal (non-hydrocephalic) but atrophied brain, a distinction not possible with conventional MR imaging studies that are presently available.

Inclusion Criteria:

• Age >21;
• One or more of the following complaints: memory loss/dementia, urinary incontinence, or progressive gait disturbance
• Ventriculomegaly defined as temporal horn width >2 mm or a FH:ID ratio>30% on computed tomography or MRI, where FH is the maximal distance between the frontal horns and ID is the internal diameter from inner table to inner table of the skull at this level (Greenberg)
• A diagnosis of any adult onset hydrocephalus (NPH, post-traumatic, post-hemorrhagic, obstructive, or idiopathic) will be considered for enrollment in this study

Exclusion Criteria:

• Implanted neuro-stimulator or cardiac pacemaker
• Known coagulopathy; major organ dysfunction
• End-stage congestive heart failure
• Oxygen-dependent pulmonary disease, hepatic cirrhosis, or dialysis- dependent renal failure; or other condition which, according to the assessment of the treating surgeon or anesthesia team
• Precludes consideration of elective surgery
• Patients who may be pregnant will be excluded from this study as well