Abstract: Calculation of the two-dimensional velocity vector of liquid flowing through a region which is imaged in a B-mode ultrasonic echoscopy display involves dividing the region into a number of small, preferably rectangular, cells. One of the cells is scanned rapidly, at least twice, by a beam of ultrasonic energy which is transmitted sequentially along a number of lines of sight which intersect the cell. An image of the cell is formed from the signals reflected from scatterers within the liquid in the cell during each scan of the cell. The two-dimensional brightness functions, S(x,y), of each image of the cell form a data set S(x,y,t) after the repeated scanning. The data set S(x,y,t) is integrated separately with respect to x and y by projection onto the (x,t) and (y,t) planes. Using the projected functions of S(x,y,t), the average velocity of the scatterers in the cell (and hence of the liquid flowing through the cell) is obtained in the x-direction and in the y-direction.

Abstract: An improved technique for establishing the position, dimensions and orientation of a vessel which is essentially free of internal acoustic discontinuities involves scanning the vessel with a beam of ultrasonic energy and, from the ultrasonic echoes received in the A-mode lines of sight of the ultrasonic beam, establishing a B-mode image of the vessel. An angle marker, in the form of a short line segment, is established, using the B-mode image, on or near a straight axis of the vessel. The length of the angle marker is divided into a number of sub-sectors, each of which receives approximately the same number of A-mode lines of sight of the ultrasonic beam. An average A-mode signal is obtained for each sub-sector. Comparison of the average A-mode signals provides information about the orientation of the angle marker relative to the axis of the vessel.