Assessment of cerebrovascular function in patients with sickle cell disease using transfer function analysis

Area of Science:

• Neurology
• Vascular Biology
• Medical Imaging

Background:

• Sickle cell disease (SCD) compromises brain oxygen delivery due to anemia, abnormal blood flow, and vascular disease.
• Effective compensation relies on increased cerebral blood flow (CBF).

Purpose of the Study:

• To assess cerebrovascular reactivity (CVR) in SCD patients using magnetic resonance imaging (MRI).
• To evaluate the dynamic response of cerebral arteries to carbon dioxide (CO2) stimulation.

Main Methods:

• MRI was used to measure the blood oxygen level dependent (BOLD) signal response to hypercapnia (increased CO2).
• Cerebrovascular reactivity (CVR) was assessed using time constant (tau) and transfer function analysis (TFA) measuring gain, phase, and coherence.
• 34 SCD patients were compared to 24 healthy controls.

Main Results:

• SCD patients exhibited significantly reduced CVR and coherence in both gray and white matter compared to controls.
• Reduced gain was observed in gray matter of SCD patients.
• The speed of response, indicated by tau and TFA phase, was significantly slower in SCD patients.

Conclusions:

• Patients with SCD have demonstrably impaired and slowed cerebrovascular responsiveness to CO2.
• These findings highlight altered brain blood flow regulation in SCD, potentially impacting neurological outcomes.