Although several three-dimensional(3D) methods for processing ultrasound images have been reported, nonreal-time reconstruction and poor definition of the edges of internal organs have precluded their clinical application. Bloodvessel perspective is one promising application of 3D ultrasound, however. We propose using power-Doppler ultrasound images of vascular flow for this purpose: power-Doppler images show Vascular flow much more clearly than do conventional B-mode or color-flow mapping. Application of a uniform threshold level enabled us to discriminate blood flow stationary tissue. Slight smoothing in 3D space for rejection of noise was sufficient. Surface rendering then prepared the 3D image for display. We used the endoscopic 3D imaging modes of MR and CT to obtain power-Doppler data and, from it, to produce images of vascular lumina. These power-Doppler-based endoscopic images readily show interior flow in arterial branches, curved vessels, and the like.