Figure 1.

Cerebral blood flow of the total gray matter (mL/100 g per min) was measured using arterial spin labeling (ASL) magnetic resonance imaging. During ASL, first an (unlabeled) control image is acquired (A). Second, water protons in the inflowing arterial blood are magnetically labeled through a radiofrequency pulse (B), and subsequently allowed enough time to reach the cerebral tissue (C). Next, an image of the labeled image is acquired (D). Subtraction of the labeled with the control image eliminates the static brain tissue with the remaining signal representing the cerebral blood flow.