Biomedical Engineering Reference
In-Depth Information
Chapter 13
Dynamic Magnetic Resonance Imaging of Cerebral Blood
Flow Using Arterial Spin Labeling
Afonso C. Silva and Fernando F. Paiva
Abstract
Modern functional neuroimaging techniques, including positron emission tomography, optical imaging
of intrinsic signals, and magnetic resonance imaging (MRI) rely on a tight coupling between neural
activity and cerebral blood flow (CBF) to visualize brain activity using CBF as a surrogate marker. Because
the spatial and temporal resolution of neuroimaging modalities is ultimately determined by the spatial and
temporal specificity of the underlying hemodynamic signals, characterization of the spatial and temporal
profiles of the hemodynamic response to focal brain stimulation is of paramount importance for the
correct interpretation and quantification of functional data. The ability to properly measure and quantify
CBF with MRI is a major determinant of progress in our understanding of brain function. We review the
dynamic arterial spin labeling (DASL) method to measure CBF and the CBF functional response with
high temporal resolution.
Key words:
Functional magnetic resonance imaging; arterial spin labeling; animal models; cerebral
blood flow; spatial resolution; temporal resolution.
1. Introduction
A major goal of neuroscience and neurophysiology is to seek
a deeper understanding of brain organization in terms of its
anatomical and functional units
(1)
. Modern neuroimaging meth-
ods, such as functional magnetic resonance imaging (fMRI)
(2)
,
positron emission tomography (PET)
(3)
and optical imaging of
intrinsic signals (OIS)
(4)
, have an increasing role in mapping ele-
mental functional units in the cerebral cortex. These functional
imaging modalities rely on the coupling of cellular activity to
the hemodynamic regulation of energy supply and waste removal
- called “cerebrovascular coupling” - to detect the changes in
