Noninvasive Perfusion measurement: basics and not-so basics of Arterial Spin Labeling. Matthias Günther is professor for magnetic resonance imaging (MRI) at the University Bremen and head of the project group on MRI physics at Fraunhofer Mevis Bremen. One focus of his research is perfusion measurement without the need of exogenous contrast agents using arterial spin labeling (ASL). M. Günther is founder and current CEO of the medical imaging research institute MEDIRI. Status: confirmed