Distinguishing Alzheimer's disease from normal pressure hydrocephalus: a search for MRI biomarkers.

Currently, no clinical or neuroradiological techniques have been validated to distinguish Alzheimer's disease (AD) from idiopathic normal pressure hydrocephalus (iNPH). Both share anatomical and clinical similarities: AD is a form of irreversible degenerative dementia, whereas the dementia manifested in iNPH is potentially "reversible" through various neurosurgical procedures. Hence, it is important to find specific imaging biomarkers that distinguish the two conditions. In addition, the ability to predict the response to neurosurgery in iNPH is something that has yet to be accomplished. In this systematic review, we describe and critically analyze the merits and drawbacks of the MR imaging parameters currently used to distinguish AD from iNPH and assess ways to predict the response after treatment of iNPH. We conclude that the combination of different neuroimaging sequences as well as quantitative and qualitative parameters could provide new insight for better diagnosis and treatment of these two different diseases.