Traditional methods for studying human coronary artery disease have significant limitations. Angiography allows evaluation only of the geometry of the remaining lumen; it cannot provide information on the structural or cellular composition of the arterial wall, which is essential to understand the processes involved in the progression of atherosclerosis. Intravascular ultrasound (IVUS) imaging is a new technology that permits tomographical visualization of a cross section through the vessel wall (Fig 1 A.) The development and refinement of IVUS has provided a powerful in vivo method to assess plaque morphology. Recent clinical studies have documented its sensitivity in detecting atherosclerosis, and it is increasingly employed to assist in selecting an appropriate therapeutic intervention. Perhaps more importantly, the potential of IVUS to quantify the structure and geometry of normal and atherosclerotic coronary arteries will allow one to characterize specific lesions and to differentiate the plaques that lead to various clinical syndromes. This study presents a three-dimensional (3D) reconstruction technique suitable for clinical use that accurately preserves 3D geometric information throughout the cardiac cycle without requiring mechanical IVUS catheter withdrawal aids.