Imaging of the coronary arteries is usually performed by X‐ray contrast angiography or intravascular ultrasound (IVUS). Angiography provides information about the vessel lumen and its geometry. IVUS offers more detailed information that also includes the vascular wall. The chapter describes these two imaging modalities and their geometrically correct fusion yielding a 3‐D and/or 4‐D representation of the coronary geometry and morphology. The image‐derived information is used for assessment of coronary function and plaque severity, blood flow related indices are determined using computational fluid dynamics. Detailed description of the methodology is followed by validation and clinical studies.