The investigator working hypothesis is an impairment of the cerebral venous drainage in IIH compared to the circulation observed in healthy volunteers considered as the reference. The research will focus on adult patients referred to the imaging department for intracranial hypertension assessment. MRI support is common for this type of request The reference will be established in a population of healthy volunteers for whom MRI blood flow measurements will be performed. In addition to the primary objective, the investigators assess the impact of IIH on CSF dynamics The study does not present any risk for the subject, any contraindication to MRI examination being respected. The subjects will undergo MRI examination including morphological and flow sequences without contrast injection. The flow sequences, in planes located at the C2-C3 and aqueductal levels, will be used to measure vascular flows (venous and arterial) and CSF oscillatory volumes. Image post-processing will be performed on a semi-automatic software allowing to extract fluid dynamics parameters.
