Cardiac magnetic resonance (CMR) is a new and promising technique for image-based diagnosis in patients with known or suspected diseases of the heart. CMR allows clinicians to obtain relevant information on anatomy, function, perfusion, and viability of the myocardium. This technique offers the advantages of versatility, lack of ionizing radiation, and superior soft tissue contrast. The variety of clinical conditions that can affect the heart and the need to understand the time-varying movement of the heart in 3 dimensions adds challenges to interpretation of CMR above and beyond those present in understanding the imaging modality itself. The image intensities present in CMR scans can vary by orders of magnitude in the same subject depending on parameters set by the individual acquiring the data. These different appearances of images may reflect distinct pathophysiologic states and, therefore, an understanding of image acquisition is fundamental to the clinical diagnosis and assessment of disease.