Arterial spin labeling (ASL) is a noninvasive magnetic resonance perfusion imaging method for visualizing and quantifying whole-brain perfusion that does not require exogenous contrast agents. The goal of this review article is to explain the principles of ASL perfusion imaging and review the strengths and limitations of different ASL methods.
There are several different approaches that vary mainly on the basis of the technique that is used to label the inflowing arterial blood. These methods can be used to assess perfusion at brain tissue level or the perfusion territories of the brain feeding arteries. In patients with acute ischemic stroke, ASL can be of clinical value by detecting brain regions with hypoperfusion and perfusion–diffusion mismatch. ASL has been used to detect decreased perfusion, delayed arrival of the arterial blood bolus and assessment of collateral blood flow in patients with extracranial large artery disease and moyamoya disease.
Recent evidence indicates that perfusion and territorial perfusion imaging of the brain feeding arteries with ASL can help to assess the extent of hemodynamic compromise and to customize medicinal and surgical treatment, both in patients with acute and with chronic cerebrovascular disease.
aDepartment of Radiology, University Medical Center Utrecht, Utrecht
bDepartment of Radiology, C.J. Gorter Center for High Field MRI, Leiden University Medical Center, Leiden
cDepartment of Neurology and Neurosurgery, Brain Center Rudolf Magnus – Stroke Unit, University Medical Center Utrecht, Utrecht
dDepartment of Radiology, Gelre Hospitals, Apeldoorn, The Netherlands
Correspondence to Reinoud P.H. Bokkers, MD, PhD, Department of Radiology, room E01.132, University Medical Centre Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands. Tel: +31 88 755 6687; fax: +31 30 258 1098; e-mail: firstname.lastname@example.org