The aim of this study is to improve the performance of imaging in the diagnosis of dementia by combining scintigraphy (SPECT) and magnetic resonance imaging (MRI) in the exploration of the striatal region . The development of this method applied to a population of subjects, with hallucinations and cognitive disorders, should demonstrate the value and complementarity of metabolic images (SPECT) and morphological (MRI) within the differential diagnosis of Lewy body dementia and the Alzheimer disease .