A GENERAL KINETIC-MODEL FOR QUANTITATIVE PERFUSION IMAGING WITH ARTERIAL SPIN-LABELING

Recently, several implementations of arterial spin labeling (ASL) tech niques have been developed for producing MRI images sensitive to local tissue perfusion. For quantitation of perfusion, both pulsed and cont inuous labeling methods potentially suffer from a number of systematic errors. In this study, a general kinetic model for the ASL signal is described that can be used to assess these errors. With appropriate as sumptions, the general model reduces to models that have been used pre viously to analyze ASL data, but the general model also provides a way to analyze the errors that result if these assumptions are not accura te. The model was used for an initial assessment of systematic errors due to the effects of variable transit delays from the tagging band to the imaging voxel, the effects of capillary/tissue exchange of water on the relaxation of the tag, and the effects of incomplete water extr action. In preliminary experiments with a human subject, the model pro vided a good description of pulsed ASL data during a simple sensorimot or activation task.