Arterial spin labeling in dementia

Abstract

Arterial spin labeling (ASL) is a type of MR perfusion imaging which utilizes magnetically labeled arterial blood as an intrinsic tracer. Because ASL involves no radioactive tracers or contrast administration, it is considered to be completely noninvasive. Moreover, ASL theoretically allows for quantitative measurement of regional cerebral blood flow (rCBF). However, ASL suffers from technical limitations including low signal-to-noise ratio and high sensitivity to arterial transit time inhomogeneity. A variety of ASL pulse sequences have been proposed, which are categorized into pulsed ASL and continuous ASL sequences. Maps of rCBF obtained with ASL are typically analyzed quantitatively, often using image statistical methods. Typical ASL findings of Alzheimer's disease include hypoperfusion in the cortical areas of the posterior cingulate and precuneus as well as the temporoparietal association cortex. Several studies have shown that ASL has high diagnostic performance in discriminating patients with Alzheimer's disease and healthy elderly subjects, although its clinical roles in diagnosing dementia have not been established.