Mapping Long-Term Functional Changes in Cerebral Blood Flow by Arterial Spin Labeling

Area of Science:

• Neuroimaging
• Physiology

Background:

• Arterial spin labeling (ASL) is valuable for mapping functional brain activity over time.
• Inter-sessional variations in basal blood flow, arterial transit times (ATTs), and alignment can cause false activation in longitudinal ASL studies.
• Reducing noise sources is crucial for accurate between-session functional ASL analysis.

Purpose of the Study:

• To assess the ability of ASL to detect functional cerebral blood flow (CBF) changes between imaging sessions separated by up to one month.
• To evaluate the impact of inter-sessional variations on the precision and reliability of ASL-based functional activation maps.

Main Methods:

• ASL data were acquired from 7 participants across three sessions to measure ATTs, resting CBF, and motor task-induced CBF changes.
• Activation maps were generated using data from within-session and between-session comparisons (up to one month apart).
• Voxel-wise reproducibility and reliability of resting grey matter CBF were assessed.

Main Results:

• Between-session activation maps showed good agreement with within-session maps, with only a 16% decrease in precision and 13% decrease in Dice similarity coefficient after one month.
• Voxel-wise reproducibility and reliability of resting grey matter CBF decreased by less than 18% for between-session analysis.
• Arterial transit time (ATT) variability between sessions was minimal, with less impact on longitudinal CBF than between-subject variability.

Conclusions:

• Voxel-wise analysis of ASL-derived CBF images acquired on different days is feasible.
• Longitudinal functional brain imaging using ASL can be achieved with only a modest loss in precision.
• ASL demonstrates significant potential for longitudinal neuroimaging studies.