Real-Time Two-Dimensional Blood Flow Imaging Using Ultrasound Doppler

Abstract

A newly developed two-dimensional blood flow imaging system which uses ultrasound is described, in which blood flow in a given cross section of a live organ is displayed in real time. To perform this, an autocorrelation technique is used. Obtained blood flow data are displayed in color on a TV screen superimposed on black/white tissue images. The flow direction, speed and variance are expressed by differences in color and brightness. Experiments were conducted with a mechanical and an electrical scanner and good agreement with the theory was obtained. Studies on clinical significance have also been carried out for normal and diseased hearts with successful results.

A Real-time Display Method for Ultrasound Color Flow Velocity Estimation

“…The flow velocity v may be written in terms of the Doppler shift frequency f d [2] cos 2 c d f cf v (2) where f c is the transducer central frequency, c the velocity of sound in tissue and the angle between the ultrasound beam and the direction of flow motion. Using the well-established autocorrelation method, the Doppler shift frequency f d at depth n is given by…”

“…The complex operation, such as arctangent (i.e., atan2) is needed to calculate the phase shift of the autocorrelation derived from Doppler signals [2], and in Section 2. To implement the atan2, one can use lookup table (LUT) to save two arguments of atan2 with a compromise between the size of the table and the accuracy of the derived atan2.…”

Color flow mapping in obstetrics

“…It can mathematically be shown that the autocorrelation function contains a number proportional to target movement velocity which can be automatically detected and displayed [4]. The limitations for color flow mapping are very similar to those affecting currently used pulsed Doppler instruments.…”