Arterial Spin Labeling MRI

In brief: Arterial spin labeling, or ASL, is an MRI perfusion technique that uses magnetically labeled blood as an endogenous tracer.

ASL can estimate cerebral blood flow without radiation or injected contrast, making repeat assessment attractive.

Use in moyamoya disease

Moyamoya collateral flow often arrives late, and a standard post-label delay may underestimate perfusion or create arterial transit artifacts.

Multi-delay techniques and interpretation alongside MRA, DSA, symptoms, and other perfusion tests can improve context. [1]

Clinical detail

ASL values are protocol-dependent. A colorful perfusion map should not be treated as an absolute measure without attention to transit time and acquisition method.

Serial studies are most useful when acquisition settings and clinical context remain comparable.