MR imaging is the premier imaging modality for diagnosing the various forms and causes of hydrocephalus. Although CT is satisfactory for imaging in the axial plane, MR imaging is capable of imaging in any plane to better demonstrate any cause of observation. MR imaging also is more sensitive than CT to interstitial edema (transependymal flow of cerebrospinal fluid [CSF]) and to the hyperdynamic CSF flow seen with shunt-responsive normal-pressure hydrocephalus (NPH). MR imaging also is sensitive to the presence of deep white matter ischemia that may contribute to the cause of the idiopathic form of NPH.