INCREASED SELF-DIFFUSION OF BRAIN WATER IN HYDROCEPHALUS MEASURED BY MR-IMAGING

We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffu sion coefficients (ADC) of brain water were found within periventricul ar white matter, in the corpus callosum, in the internal capsule, with in cortical gray matter, and in cerebrospinal fluid, whereas normal AD Cs were found within the basal ganglia. In 2 patients with HPH elevate d ADCs were found most prominently within white matter, and in one pat ient reexamined one year after surgery, ADCs were unchanged in nearly all brain regions. The increased ADC values in hydrocephalus patients may be caused by factors such as changes in myelin-associated bound wa ter, increased Virchow-Robin spaces, and increased extracellular brain water fraction. For further studies of brain water diffusion in hydro cephalus patients, echo-planar imaging techniques with imaging times o f a few seconds may be valuable.