Whole-Brain Vascular Architecture Mapping Identifies Region-Specific Microvascular Profiles In Vivo

Area of Science:

• Neuroimaging
• Cerebrovascular Research
• Medical Physics

Background:

• Vascular architecture mapping (VAM) is a novel MR imaging technique for in vivo characterization of cerebral microvasculature.
• Reference ranges for VAM parameters in healthy brain tissue are currently lacking, hindering its clinical application as an MR imaging biomarker.
• This study aimed to establish reference ranges for VAM parameters in a large cohort of healthy adults.

Purpose of the Study:

• To conduct whole-brain vascular architecture mapping in a large cohort to establish reference ranges for VAM parameters.
• To identify region-specific cortical and subcortical microvascular profiles in the healthy adult brain.
• To provide a foundation for using VAM as a biomarker in clinical practice for cerebrovascular pathologies.

Main Methods:

• Whole-brain VAM was performed using a multiband spin- and gradient-echo EPI sequence at 3T.
• Vessel vortex curves were generated by plotting gradient-echo (R2*) versus spin-echo (R2) relaxation rates during contrast agent administration.
• VAM parameters (e.g., vessel type, radius, CBV) were extracted, and whole-brain parametric maps and region-specific analyses were conducted.

Main Results:

• Cortical gray matter (GM) exhibited larger mean vascular calibers and increased blood volume fraction compared to white matter (WM).
• Distinct microvascular profiles were observed between different brain regions, such as the thalamus and cortical GM.
• High test-retest reliability was demonstrated for VAM parameter mean values.

Conclusions:

• Whole-brain VAM successfully revealed region-specific microvascular profiles in the adult brain.
• Established parameter reference ranges can be utilized for future VAM studies investigating cerebrovascular pathologies.
• This technique may facilitate the early detection of microvascular changes in neurodegenerative diseases and neuro-oncology.