Cross-beam vector Doppler ultrasound for angle-independent velocity measurements

Combining Doppler measurements taken along multiple intersecting ultrasound (US) beams is one approach to obtaining angle-independent velocity. Over 3 0 laboratories and companies have developed such cross-beam systems since t he 1970s. Early designs focused on multiple single-element probes. In the l ate 1980s, combining multiple color Doppler images acquired from linear-arr ay transducers became a popular modality. This was further expanded to incl ude beam steering and the use of subapertures. Often, with each change in d esign, came a new twist to calculating the velocity. This article presents a review of most proposed cross-beam systems published to date. The emphasi s is on the basic design, the approach used to determine the angle-independ ent velocity, the advantages of the design, and the disadvantages of the de sign. From this, requirements needed to convert the idea of angle-independe nt vector Doppler into a commercial system are suggested. (C) 2000 World Fe deration for Ultrasound in Medicine & Biology.