 Participation in this study will involve having an MRI of the heart. This study will allow us to determine the ability to measure the volumes of your heart chambers in both the left and right side of your heart without using any aggressive invasive technique or the use of ionizing radiation x-rays or gamma rays. The study will also allow us to measure changes in the cardiac chamber volumes during the cardiac cycle and determine whether this can be done rapidly and accurately. The study will also allow us to determine whether this technique can be used for routine clinical use. 