Chapters in Section I include many modalities that currently produce direct images of cardiovascular structures and their function (eg, coronary angiography, echocardiography, SPECT, and magnetic resonance imaging). Because the inexpensive and widely available electrocardiogram (ECG) is now being developed into an imaging modality, several chapters are devoted to considering the perspectives of standard scalar ECG, spatial dipolar electrocardiotopographic [DECARTO] imaging, the inverse problem of ECG (ie, deducing cardiac excitation patterns from body surface recordings), and autonomic modulation. Section II covers the emerging technologies that are leading to the creation of direct imaging of cardiac activation and recovery. This requires extensive mathematical modeling by physicists, engineers, and computer scientists in concert with the academic clinician-investigators who will ultimately use the methods for their diagnostic and therapeutic decision support. Three of the imaging modalities that exist as simulations or models, rather than as clinically available methods, are considered in dedicated chapters: "Cardiac Simulation for Education: Electromechanical Modeling Applied to Cardiac Resynchronization Therapy" (Chapter 13 by Constantino et al), "Computational Cardiac Electrophysiology: Modeling Tissue and Organ" (Chapter 14 by Bishop et al), and "The Electrocardiogram According to ECGSIM" (Chapter 15 by van Oosterom et al). These methods are currently used to guide clinical investigators in the development and evaluation of new cardiovascular therapies and might be developed into clinically useful tools in the future.