Arterial Spin Labeling (ASL) fMRI: Advantages, Theoretical Constrains and Experimental Challenges in Neurosciences

Figure 1

Schematic presentation of how ASL signal is obtained. The first three panels represent the signal from a single imaged voxel that originates from the control (left), label (center), and control-label difference (right) panels, respectively. The numbers are not meant to represent real flow. A real CBF image is shown in the rightmost panel. The color bar represents flow in [0–107] mL/100 g·min range. Note that, as mentioned in text, the difference ▵=(𝑀_𝐶−𝑀_𝐿) image is converted to a single CBF image via a function that includes physiological and MR parameters such as relaxation rates, transit times, and blood tissue water partition coefficient, 𝜆.