Magnetic resonance measurements will be performed in the magnet and are very similar to magnetic resonance imaging exams (MRI). Subjects will always have the possibility to signal when they feel claustrophobic and wish to be removed from the magnet. The magnetic resonance measurements will be associated with a regular clunking noise that subjects may initially find unpleasant. For their comfort they will be offered to wear ear plugs. During the measurements in the magnet subjects will be asked to lie still for most of the time.