Perfusion imaging using dynamic arterial spin labeling (DASL)

Recently, a technique based on arterial spin labeling, called dynamic arter ial spin labeling (DASL (Magn Reson Med 1999;41:299-308)), has been introdu ced to measure simultaneously the transit time of the labeled blood from th e labeling plane to the exchange site, the longitudinal relaxation time of the tissue, and the perfusion of the tissue. This technique relies on the m easurement of the tissue magnetization response to a time varying labeling function. The analysis of the characteristics of the tissue magnetization r esponse (transit time, filling time constant, and perfusion) allows for qua ntification of the tissue perfusion and for transit time map computations. In the present work, the DASL scheme is used in conjuction with echo planar imaging at 4.7 T to produce brain maps of perfusion and transit time in th e anesthetized rat, under graded hypercapnia. The data obtained show the va riation of perfusion and transit time as a function of arterial pCO(2), Bas ed on the data, CO2 reactivity maps are computed. Published 2001 Wiley-Liss , Inc.(dagger).