COMPARATIVE MICROVASCULAR PROFILING IN SPEECH-RELATED BRAIN REGIONS USING ARTERIAL SPIN LABELING MAGNETIC RESONANCE IMAGING: A STUDY OF HEALTHY INDIVIDUALS AND MOYAMOYA PATIENTS

Abstract

Cerebral perfusion, which represents the delivery of oxygen-rich blood to the brain, is vital for maintaining cognitive and neurovascular function. Critically, it progressively declines with age and in the presence of cerebrovascular disease. Arterial spin labeling (ASL) magnetic resonance imaging (MRI) is a noninvasive imaging technique that uses radiofrequency labeled arterial blood water as an endogenous tracer to measure cerebral blood flow (CBF; measure of perfusion) and arterial transit time (ATT; the time it takes blood to reach brain tissue). ASL is well-suited for studying microvascular changes across the lifespan and in clinical populations, due to its quantitative, safe, and repeatable nature. This study leverages ASL to examine CBF in cortical regions involved in speech and auditory processing across two populations: (1) neurologically normal adults from the Human Connectome Project–Aging (HCP-A), and (2) patients with MMD, a rare but severe cerebrovascular condition, from the Vanderbilt Assessment of Multi-Model MRI Patients at Risk for Stroke with Intracranial Stenosis (VAMMPRIS) dataset. In the healthy cohort, aging was associated with widespread declines in CBF and increases in ATT in left-lateralized language regions. Even in the absence of overt disease, individuals taking antihypertensive medications exhibited significantly reduced CBF and delayed ATT in multiple regions, highlighting the impact of systemic vascular burden on brain perfusion. Individuals with Moyamoya Disease (MMD) showed more pronounced reductions in CBF across all speech-related cortical regions, reflecting severe hypoperfusion. Sex-stratified analysis revealed that males with Moyamoya exhibited a steeper age-related decline in CBF than their female counterparts. Detection of subtle and severe perfusion deficits with ASL MRI demonstrates its potential as a tool for monitoring cerebrovascular health across the spectrum of aging, hypertension, and disease. By characterizing how CBF is altered in specific brain regions, this study contributes to a better understanding of how vascular risk factors shape neurovascular aging and highlights the clinical value of ASL in identifying individuals at risk for cerebrovascular conditions.