Trajectories of normal cerebral blood flow development in youth. Commentary on: Liu etal. Resting state cerebral blood flow with arterial spin labeling MRI in developing human brains.

Abstract

Neurodevelopment—including changing neural activity– continues from childhood through adolescence into early adulthood. As neural activity in the brain changes, through neurovascular coupling, cerebral blood flow (CBF) adjusts to meet associated energy demands. The distribution of regional CBF (rCBF) thereby reflects functional neuroanatomy in health and disease. Positron emission tomography (PET), single-photon emission computed tomography (SPECT), and perfusion computed tomography all assay rCBF, but high cost and use of radiotracers or contrast agents render these techniques suboptimal in children, especially healthy children. Thus, pediatric normal developmental CBF data have been sparse with many extant findings deriving from pseudo-clinical samples. The non-invasive MRI-based arterial spin labeling (ASL) method, on the other hand, uses blood water as an endogenous tracer. The spins of the water protons in an upstream tissue volume are inverted and, after delay, magnetization is measured in a second, downstream volume to quantify CBF. ASL has been validated against PET, SPECT, and dynamic susceptibility contrast (DSC) MRI. ASL is safe and logistically suitable for children and can be repeated arbitrarily often. Unlike another safe method, BOLD fMRI, which produces a composite signal, ASL returns CBF as a single physiological endpoint. ASL can also measure signals at lower frequencies than BOLD. Thus, ASL is an apt modality to determine the trajectory of cerebral perfusion in neurodevelopment. Resting state cerebral blood flow with arterial spin labeling MRI in developing human brainsEuropean Journal of Paediatric NeurologyVol. 22Issue 4PreviewThe development of brain circuits is coupled with changes in neurovascular coupling, which refers to the close relationship between neural activity and cerebral blood flow (CBF). Studying the characteristics of CBF during resting state in developing brain can be a complementary way to understand the functional connectivity of the developing brain. Arterial spin labeling (ASL), as a noninvasive MR technique, is particularly attractive for studying cerebral perfusion in children and even newborns. Full-Text PDF