Figure 5. Diagram on an arterial spin labelling(ASL) time course. In this graph, an example of two voxels having the same flow (60 ml 100 g^–1 min^–1) and relaxation characteristics, but different arrival time, is presented. The measured signal at a single inversion time of 1.5 s would result in a 12% lower M signal in a voxel with delayed arrival of 500 ms (open square) as compared with a voxel with an arrival time of 200 ms (closed square).