CESTw imaging in body areas with significant physiological motion is strongly hampered because of the inherent motion sensitivity of this MRI technique. In particular, slow physiological motion in the abdomen, e.g. peristaltic motion or bladder filling may lead to Z-spectral inconsistency and artifacts in CESTw images. Here, a method is introduced which analyzes Z-spectral consistency to mask CESTw image areas affected by motion. The technique is successfully demonstrated on a volunteer example in liver CESTw MRI, indicating a future application in body oncology.