1. A method of reconstructing a 3D image, comprising the steps of: (a) scanning the object with a 2D scanner; (b) recording a succession of scans at different positions and angles such as to record echos from a volume to be examined; (c) recording the position of each scan plane; (d) discriminating between tubular blood-filled areas and other tissues and anechoic areas by applying nonlinear image processing techniques; and (e) displaying only the blood-filled areas in a three-dimensional projection with control of view angle and rotation.