<i>Background</i> - Positron emission tomography (PET)/magnetic resonance (MR) imaging may become increasingly important for assessing tumor therapy response. A prerequisite for quantitative PET/MR imaging is reliable and repeatable MR-based attenuation correction (AC).<p> <p><i>Purpose</i> - To investigate the frequency and test–retest reproducibility of artifacts in MR-AC maps in a lung cancer ...