Colour flow and motion imaging

Abstract

Colour flow imaging (CFI) is an ultrasound imaging technique whereby colour-coded maps of tissue velocity are superimposed on grey-scale pulse-echo images of tissue anatomy. The most widespread use of the method is to image the movement of blood through arteries and veins, but it may also be used to image the motion of solid tissue. The production of velocity information is technically more demanding than the production of the anatomical information, partly because the target of interest is often blood, which backscatters significantly less power than solid tissues, and partly because several transmit-receive cycles are necessary for each velocity estimate. This review first describes the various components of basic CFI systems necessary to generate the velocity information and to combine it with anatomical information. It then describes a number of variations on the basic autocorrelation technique, including cross-correlation-based techniques, power Doppler, Doppler tissue imaging, and three-dimensional (3D) Doppler imaging. Finally, a number of limitations of current techniques and some potential solutions are reviewed.

Flow Velocity Mapping Using Contrast Enhanced High-Frame-Rate Plane Wave Ultrasound and Image Tracking: Methods and Initial in Vitro and in Vivo Evaluation

“…Additionally, because of the weak scattering from blood cells, Doppler also has a trade-off between spatial/temporal resolution and signal-to-noise ratio (SNR). The performance can also be affected by various artifacts because of aliasing and beam-flow angle variations (Evans and Wells 2010). Some new Doppler techniques have been developed, including crossed-beam vector Doppler (Kripfgans et al 2006;Pastorelli et al 2008;Ricci et al 2014;Tortoli et al 2010), vector flow mapping (Ohtsuki and Tanaka 2006;Uejima et al 2010), directional cross-correlation method (Jensen and Lacasa 1999;Kortbek and Jensen 2006), transverse oscillation method (Pedersen et al 2014;Udesen and Jensen 2006), and pulse inversion Doppler (Simpson et al 1999;Tremblay-Darveau et al 2014).…”

3d Power Doppler in Obstetrics

“…As a result all frequency information including flow direction and velocity is eliminated 23 . Signal is thus governed by the volume of moving blood rather than its velocity 24 and it is proportional to the number of moving scatterers within an isonated volume 25 . Signal is displayed as differing hues of a single colour, often ranging from yellow through orange to red, the lighter the hue the greater the intensity of the signal 19 .…”

“…1 Noise suppression: Power Doppler is less affected by random noise, which is of variable frequency and low, uniform power 24 . As a result, if the sensitivity of power Doppler signal detection is adjusted to just above this noise level, the dynamic range of the scanner is increased and even low velocity flow is easily detected as it has more power than noise.…”

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

“…Many methods have been proposed to overcome these limitations (reviewed by Taylor & Draney [14] and Evans [15,16]). The most notable are vector Doppler and speckle tracking [17,18].…”