Haemdall: Developing a Quantitative MRI Biomarker of Infratentorial Superficial Siderosis of the Central Nervous System

Inclusion Criteria: Superficial siderosis cohort: * Male or female adults of 18 years of age or older with a confirmed diagnosis of superficial siderosis * Participants who have the capacity and a level of English proficiency that allows him/her to communicate well with the Investigator, understand and comply with the requirements of the investigation, read all participant facing documentation, as well as read and sign the informed consent form. * Participants willing and able to give informed consent for participation in the investigation Healthy cohort: * Male or female over 18 years of age without a diagnosis of a neurological disorder * Participants who have the capacity and a level of English proficiency that allows him/her to communicate well with the Investigator, understand and comply with the requirements of the investigation, read all participant facing documentation, as well as read and sign the informed consent form. * Participants willing and able to give informed consent for participation in the investigation Exclusion Criteria: * The participant may not enter the investigation if they have any contraindication to magnetic resonance imaging (including pregnancy, extensive tattoos, pacemaker, shrapnel injury or metallic unfixed implanted devices, metallic fragments, severe claustrophobia and cochlear implants) * Any other cause, including a significant disease or disorder which, in the opinion of the investigator, may either put the participant at risk because of participation in the investigation, or may influence the result of the investigation, or the participant's ability to participate in the investigation * Participants who do not demonstrate the capacity to understand the investigation information or provide informed consent