Lung cancer is the most frequently diagnosed cancer worldwide. Radiation therapy (RT) is standard-of-care in one-third of the patients, where the incidence of cardiac complications in lung cancer patients after RT reaches 33%. The current paradigm for cardiotoxicity detection and management relies primarily upon assessment of ejection fraction (EF). However, cardiac injury can occur without a clear change in EF. In this study, we investigate the effect of RT on global and regional cardiac function and myocardial T1/T2 values. The results show the capability of regional cardiac MRI for depicting early changes in myocardial contractility pattern and tissue characterization post-RT.