[Diffusion tensor imaging (DTI) in the differential diagnosis of normal pressure hydrocephalus and brain atrophy]

Clinical symptomatology of idiopathic normal pressure hydrocephalus, due to its overlap with dementias and neurodegenerative brain disorders, makes diagnosis challenging. As the neurological deficits are reversible there is a need for prompt and reliable noninvasive testing. The aim was to try to use and introduction into clinical practice of new non-invasive method--diffusion tensor imaging (DTI-Diffusion Tensor Imaging) discriminating patients classified as normal pressure hydrocephalus and patients diagnosed with brain atrophy.

Using magnetic resonance-diffusion tensor imaging, we examined white matter changes within the brains of patients diagnosed with idiopathic normal pressure hydrocephalus, cerebral atrophy and controls. Diffusion tensor brain images were obtained with 3Tesla and 1.5 Tesla MR-scanners. Fractional anisotropy brain maps were generated using a computer-automated method, and tract-based spatial statistics were then applied to compare the fractional anisotropy values in the clinical groups. The fractional anisotropy data were further investigated using region-of- interest analysis set within: fibre commissural the lateral ventricles (Fclv), forceps minor of corpus callosum (Fmin), cingulum (Cg), optic radiation (Orad), superior cerebellarpeduncle (Scp), substantia nigra (nucleus ruber) (Sn).

Compared with the cerebral atrophy or control group, the FA values in the hydrocephalus group were significantly different in the posterior cingulate (Cg) and the forceps minor of the corpus callosum (Fmin).

The pattern of white matter tracts changes in select brain regions distinguishes it from cerebral atrophy and control brains. Our pilot study adds to the body of knowledge advancing the understanding of the white matter pathology of idiopathic normal- pressure hydrocephalus.