Ultrasound Vector Flow Imaging: I: Sequential Systems

Abstract

Abstract-The paper gives a review of the most important methods for blood velocity vector flow imaging (VFI) for conventional, sequential data acquisition. This includes multibeam methods, speckle tracking, transverse oscillation, color flow mapping derived vector flow imaging, directional beamforming, and variants of these. The review covers both 2-D and 3-D velocity estimation and gives a historical perspective on the development along with a summary of various vector flow visualization algorithms. The current state-of-the-art is explained along with an overview of clinical studies conducted and methods for presenting and using VFI. A number of examples of VFI images are presented, and the current limitations and potential solutions are discussed.

Ultrasound imaging velocimetry with interleaved images for improved pulsatile arterial flow measurements: a new correction method, experimental and in vivo validation

“…The difference is likely to be due to the practical difficulty of aligning the transducer with the centre of the aorta and holding it steady, as well as the known errors in Doppler ultrasound; in vivo Doppler velocity measurement errors may be up to 75% even with an experienced sonographer [10,50]. Peak systolic flow was calculated to be 175 ml min 21 , within the range found for similar anaesthetized rabbits [51].…”

“…The mean absolute difference compared with Doppler was 11 cm s 21 and compared with transit time flow rate was 84 ml min 21 . This happens, because when Dt is smaller, the displacement of the scatterers between the two frames is smaller and hence the velocity resolution is reduced.…”

“…Since 2000, a technique known as ultrasound imaging velocimetry (UIV) or echo-particle image velocimetry (echo-PIV) by analogy with the popular optical technique, has been under development [19]. In this method, regions of two successive B-mode images of a fluid containing scatterers are cross-correlated to calculate two-dimensional velocity vectors [20][21][22]. Hence, the method produces instantaneous, two-dimensional velocity vector fields.…”

“…Restricting the field of view [34], or skipping lines [35], can increase the frame rate but at the expense of reduced image width or detail. Leow et al [36] used plane wave imaging, in which the whole image frame is captured simultaneously, to achieve frame rates of 1000 Hz and measured velocities up to 80 cm s 21 . Other examples of the use of high frame rates achieved with plane wave imaging are: UIV of the common carotid [37]; vector Doppler of healthy and diseased carotid arteries [38]; and transverse oscillation of carotid and brachial arteries [39].…”

“…Poelma & Fraser [40] showed how interleaving images can increase the dynamic range up to at least 140 cm s 21 while maintaining the full image. The technique works by halving the beam sweep speed, so that there is time in between each line of the first image to produce a line of the second image.…”