MRI multiparametric hemodynamic characterization of the normal brain

Area of Science:

• Neuroimaging
• Vascular Biology
• Medical Physics

Background:

• Cerebrovascular disease assessment relies on understanding the brain's vascular system.
• Multiparametric characterization of brain hemodynamics is essential for clinical evaluation.
• Establishing reference values in healthy brains is a prerequisite for pathology detection.

Purpose of the Study:

• To characterize brain hemodynamics in healthy subjects using multimodal MRI.
• To obtain reference hemodynamic values for different brain tissues and vascular structures.
• To investigate the impact of hypercapnia and carbogen challenges on brain hemodynamics.

Main Methods:

• Multimodal magnetic resonance imaging (MRI) including dynamic susceptibility contrast imaging and BOLD.
• Unsupervised cluster analysis to define brain tissues (gray matter, white matter, blood vessels and dura).
• Calculation of hemodynamic parameters and bolus arrival times under controlled respiratory challenges.

Main Results:

• Carbogen challenge yielded a BOLD signal twice as high as hypercapnia.
• Hemodynamic characteristics showed graded vascularity: blood vessels and dura > gray matter > white matter.
• Significant delays in bolus arrival time were observed in posterior cerebral artery territory and in veins versus arteries.

Conclusions:

• This study provides crucial reference hemodynamic values from healthy brains.
• The findings highlight significant differences in hemodynamics across brain tissues and vascular territories.
• These reference values are vital for assessing patients with cerebrovascular pathologies.