The primary aim of this study is to evaluate MRI-based cerebrovascular reserve (CVR) measurements in adult patients with Sickle Cell Disease (SCD).

The primary objective is to assess whether there is a correlation between CVR and silent cerebral infarcts (SCIs).

CVR is hypothesized to be impaired in SCD patients and could account for the white matter hyperintensities seen on MRI in these patients. Cerebral blood flow (CBF) alone is not sufficient to provide insight into the hemodynamic status of the brain. CVR allows us to gain insight into the capacity of the cerebrovasculature to respond to increased CBF. Vasculopathy is common in SCD and the caliber of the vessels can be assessed with 4D Flow MRI in response to actue and chronic changes in the velocity and wall shear stress on the intracranial arteries in the Circle of Willis.

This study will be performed as a single center, patient-control, cross-sectional, observational study in patients with steady-state SCD and controls. The investigators expect that patients with impaired CVR will have a greater number and/or volume of SCIs.

Inclusion Criteria Patient group:

• Sickle cell disease; either homozygous sickle cell disease (HbSS), or HbSβ0 thalassemia
• 18 years of age or older
• Informed consent

Inclusion Criteria Control group:

• Similar ethnic background as Patient group
• 18 years of age or older
• Informed consent

Exclusion Criteria Patient group and Control group:

• Inability of the patient to provide informed consent or legally incompetent/incapacitated to do so
• Contraindications for MRI, such as pregnancy, claustrophobia or the presence of metal in the body
• Sickle cell crisis at the moment of participation
• History of cerebral pathology that compromises measurements, such as cerebral palsy, brain tumour,meningitis, overt infarct
• Brain surgery performed in the last 3 months
• Severe liver, heart or renal dysfunction (clearance < 10 mL/min)
• Allergy to sulphonamide
• Breastfeeding
• Use of phenytoin, procaine or acetylsacylic acid ("Ascal/aspirin")
• Risk of hypokalaemia (use of diuretics, primary hyperaldosteronism)
• Addison's Disease
• Severe asthma or emphysema

Patients are eligible if they have a diagnosis of sickle cell disease; either homozygous sickle cell disease (HbSS), or HbSβ0 thalassemia and are in a steady disease state i.e. no crisis requiring hospitalization 4 weeks prior to participation.