Acetazolamide's Headache Inducing Characteristics and Effects on the Cerebral Arteries and Blood Flow

To investigate headache score and accompanying symptoms during and after infusion of acetazolamide. With magnetic resonance imaging the investigators will investigate changes in regional cerebral blood flow (rCBF) in the area supplied by middle cerebral artery (MCA), diameter of MCA, the Internal carotic artery (ICA), the superficial temporal artery (STA) and the Medial Meningeal artery (MMA).