Fig. 6.

Vertical distributions of blood delivered from terminal arterioles (acinar flow, solid black lines), total ASL signal (black dashed lines), and ASL signal following the removal of all voxels with an intensity >35% of maximum (solid gray lines). A–E: correspond to sagittal image planes 1–5 respectively. Scale for A–C is the same, as is the scale for D and E, but these are different from each other. Data were collected into 20-mm-high strips (each strip is iso-gravitational in orientation). Note that in A–C, the intensity filter results in a reasonable agreement between acinar flow and ASL signal. However, in the more medial image planes (D and E) the result is a substantial overcorrection as a result of a very high proportion of in-plane flow in these locations (see Blood flow distribution and heterogeneity with intensity cutoff for details).