Age-related changes in cerebral blood flow and arterial transit time in children: insights from single- and...

Arterial spin labeling (ASL) MRI is a non-invasive perfusion imaging technique with potential for assessing hemodynamics in children. However, understanding hemodynamic changes in developing brains remains challenging. This study investigates the impact of normal brain development on ASL-derived cerebral blood flow (CBF) and arterial transit time (ATT) in MR-negative children.

Thirty-two pediatric subjects (ages 0.7-17.9 years, mean 9.3 ± 5.3y, 19 male) with MR-negative findings were retrospectively included. Four pseudo-continuous ASL (PCASL) scans were acquired: single-delay (PLD 1525 or 2025 ms) and multi-delay (3 or 7 delays). CBF and ATT in supratentorial gray matter (GM), white matter (WM), and total-brain (TB) regions were analyzed using paired t-tests, Cohen's d, Spearman correlation, and mixed linear regression models.

Single-delay CBF was significantly higher than 3-delay CBF in GM and WM (p < 0.001 PLD 2025 ms; p = 0.02 PLD 1525 ms). WM and TB CBF correlated negatively with age (rho=-0.56, p < 0.001), whereas GM CBF showed no significant correlation (rho=-0.03, p = 0.87); the trends differed significantly (p = 0.01). GM and TB ATT increased with age (r² > 0.11, p < 0.021). WM and TB CBF correlated with WM and combined WM/GM volumes (rho=-0.42, p = 0.02; rho=-0.46, p = 0.008).

GM and WM exhibit distinct age-related hemodynamic patterns. WM perfusion declines with age and correlates with WM volume, while GM perfusion remains stable. The progressive increase in GM ATT highlights the need for cautious interpretation of single-delay ASL data in pediatric studies.