The progress in clinical applications of arterial spin labeling technique

As a kind of MR perfusion imaging methods, arterial spin labeling (ASL) takes water in arterial blood, which is freely diffusible, as an endogenous tracer. Through quantitatively measuring local relative blood flow, ASL can provide tangible proofs for diseases diagnosis. Not like dynamic susceptibility contrast enhanced MR perfusion, it does not need exogenous contrast agent. With the advantage of noninvasiveness, simplicity, relatively lower costs and repeatability, it has strong potential in clinical application. In this review we mainly focued on the principle, categories, clinical applications, and future prospects of ASL. (authors)