Figure 1.

Schematic figures illustrating the potential issues that could arise when motion correction (MoCo) is applied to background suppressed (BGS) ASL acquired with simultaneous multi‐slice (SMS) EPI. A, BGS image of conventional 2D‐EPI and SMS‐EPI pCASL, where yellow circles show slices with the most effective and poorest BGS immediately next to each other. (B) Dark lines observed on reformatted images, produced by slices with the most effective and poorest BGS (BGS dark lines). (C) Subtraction between a control image without motion and a label image with through‐plane rotation (realigned). The red circle shows the subtraction errors caused by the different background static signal intensity between control and label images (BGS subtraction errors)