A QUANTITATIVE INTERPRETATION OF IVIM MEASUREMENTS OF VASCULAR PERFUSION IN THE RAT-BRAIN

Pulsed gradient spin echo (PGSE) sequences have been used to measure t he signal loss of F-19 in perfluorinated hydrocarbon blood substitutes moving within the vasculature of the rat brain in the experimental co nditions of the study. The signal loss is not characterized by a singl e apparent pseudodiffusion coefficient. A simple vascular network mode l based on selfsimilarity has been used to calculate the shape of the signal loss. Excellent agreement with the experiment has been obtained showing that the IVIM measurements are sensitive to flow over a wide range of vessel diameters and flow rates. This model of vascular struc ture may serve well for other MR measurements that are sensitive to pe rfusion.