Arterial spin labeling characterization of cerebral perfusion during normal maturation from late childhood into adulthood: normal 'reference range' values and their use in clinical studies.

The human brain changes structurally and functionally during adolescence, with associated alterations in cerebral perfusion. We performed dynamic arterial spin labeling (ASL) magnetic resonance imaging in healthy subjects between 8 and 32 years of age, to investigate changes in cerebral hemodynamics during normal development. In addition, an inversion recovery sequence allowed quantification of changes in longitudinal relaxation time (T₁) and equilibrium longitudinal magnetization (M₀). We present mean and reference ranges for normal values of T₁, M₀, cerebral blood flow (CBF), bolus arrival time, and bolus duration in cortical gray matter, to provide a tool for identifying age-matched perfusion abnormalities in this age range in clinical studies. Cerebral blood flow and T₁ relaxation times were negatively correlated with age, without gender or hemisphere differences. The same was true for M₀ anteriorly, but posteriorly, males but not females showed a significant decline in M₀ with increasing age. Two examples of the clinical utility of these data in identifying age-matched perfusion abnormalities, in Sturge-Weber syndrome and sickle cell anemia, are illustrated.