High-frame rate vector flow imaging of the carotid bifurcation

Abstract

Carotid artery atherosclerotic disease is still a significant cause of cerebrovascular morbidity and mortality. A new angle-independent technique, measuring and visualizing blood flow velocities in all directions, called vector flow imaging (VFI) is becoming available from several vendors. VFI can provide more intuitive and quantitative imaging of vortex formation, which is not clearly distinguishable in the color Doppler image. VFI, as quantitative method assessing disturbed flow patterns of the carotid bifurcation, has the potential to allow better understanding of the diagnostic value of complex flow and to enhance risk stratification. This pictorial review article will show which new information VFI adds for the knowledge of hemodynamics in comparison to the conventional ultrasound techniques.Teaching points• VFI is an angle-independent technique measuring flow velocities in all directions. • This kind of VFI is based on a plane wave multidirectional excitation technique. • VFI allows quantitative assessment of carotid streamlines progression and visualizes vorticity. • VFI does not allow a precise comprehension of streamlines’ 3D shape. • VFI allows a better understanding of carotid artery complex flows. Electronic supplementary materialThe online version of this article (doi:10.1007/s13244-017-0554-5) contains supplementary material, which is available to authorized users.

Blood flow reversal from the external into the internal carotid artery—New insights into the hemodynamics at the carotid bifurcation

“…The temporal resolution of VFI with 500–600 images per second exceeds the temporal resolution of CDS approximately by the factor 30. As shown by Goddi and colleagues, VFI could better visualize the complex blood flow at the carotid bifurcation and discriminate multiple complex flow patterns like flow separation, recirculation, counter‐eddies, multiple eddies, and vortexes (Goddi, Bortolotto, et al, ; Goddi, Fanizza, et al, ; Goddi et al, ). The blood flow reversal from the ECA into the ICA now extends this spectrum of complex flow patterns at the carotid bifurcation.…”

“…VFI allows the calculation of the true velocity vectors at any location into a vessel and shows velocity vectors, streamline distribution, and vorticity distribution at high frame rates. (Ekroll, Dahl, Torp, & Løvstakken, ; Goddi, Bortolotto, et al, ; Goddi, Fanizza, et al, ).…”

Riding the Plane Wave: Considerations for In Vivo Study Designs Employing High Frame Rate Ultrasound

“…Another point worth noting is that one clinical scanner developer (Supersonic Imagine, Aux-du-Province, France) is currently dedicated to the development of the HiFRUS market [38]. Also, specialized HiFRUS flow vector imaging modes are available on clinical scanners developed by Analogic Ultrasound (Peabody, MA, USA) [39] and Mindray (Shenzhen, China) [40].…”

“…For instance, by integrating HiFRUS with Doppler estimation principles, it is possible to achieve time-resolved visualization of complex flow dynamics through the rendering of flow speckles [9] and the derivation of flow vectors at different pixel positions [44] as illustrated in the sample images in Figure 1. Not only is this useful in examining carotid hemodynamics [8,40], it is also applicable to the evaluation of arterial strain [45][46][47], the visualization of pulse wave propagation through the artery wall [48], and the tracking of shear waves propagating in tissues [35,49]. HiFRUS may also be used in urology applications to gain time-resolved insight into turbulent urinary flow behavior [50].…”

Vector flow imaging techniques: An innovative ultrasonographic technique for the study of blood flow

“…They measure at least two of the three components of a velocity vector to calculate the true flow vector and the velocity magnitude, providing both spatial and temporal vector information without the need of any angle correction . VFI allows the calculation of the true velocity vectors at any location into a vessel and shows velocity vectors, streamline distribution, and vorticity distribution …”