Two major imaging modalities are frequently used in current cardiovascular practice: biplane X-ray angiography and intravascular ultrasound (IVUS). We have previously developed a methodology for three-dimensional reconstruction of coronary vessels via a fusion of two-dimensional data from the two imaging modalities. Our data fusion technique provides a tool for accurate three- and four-dimensional measurements in coronary arteries in vivo.This paper documents recent additions to enable accurate three-dimensional volumetric and four-dimensional velocity measurements. Accurate three-dimensional volumetric measurements are of great use to the study of vessel diseases, such as atherosclerosis, while vessel velocities are of great importance when determining adequate sampling rates in the design of new imaging hardware. Validation of both methods has been performed in computer simulations, yielding minimal errors. The quantification of the vessel velocity has been tested on routine patient data, and provided results that were both consistent and in accordance with physiology.