What can we learn from arterial spin labeling MRI about pain?

Arterial spin labeling (ASL) has recently become a promising new tool in the investigation of various pathological states including chronic pain. In contrast to the most widely used BOLD fMRI, it provides a direct measure of tissue perfusion and is more sensitive for experimental paradigms with long periods – a feature that is critical particularly in the investigation of persistent pain states. Recently published ASL data on experimental pain confirm activations in previously identified pain-sensitive brain regions but also allowed for the direct quantification of the increase and decrease in blood flow. ASL is currently used to study clinical pain and preliminary data suggest that this technique can provide new insights in the pathophysiology underlying ongoing pain.