Contrast-Enhanced High-Frame-Rate Ultrasound Imaging of Flow Patterns in Cardiac Chambers and Deep Vessels

Abstract

Cardiac function and vascular function are closely related to the flow of blood within. The flow velocities in these larger cavities easily reach 1 m/s, and generally complex spatiotemporal flow patterns are involved, especially in a non-physiologic state. Visualization of such flow patterns using ultrasound can be greatly enhanced by administration of contrast agents. Tracking the high-velocity complex flows is challenging with current clinical echographic tools, mostly because of limitations in signal-to-noise ratio; estimation of lateral velocities; and/ or frame rate of the contrast-enhanced imaging mode. This review addresses the state of the art in 2-D highframe-rate contrast-enhanced echography of ventricular and deep-vessel flow, from both technological and clinical perspectives. It concludes that current advanced ultrasound equipment is technologically ready for use in human contrast-enhanced studies, thus potentially leading to identification of the most clinically relevant flow parameters for quantifying cardiac and vascular function.

Optimization of Microbubble Concentration and Acoustic Pressure for Left Ventricular High-Frame-Rate EchoPIV in Patients

“…Some echocardiographic techniques are able to estimate both the magnitude and direction of the blood velocity vectors, which we collectively name vector flow imaging (VFI) techniques -prominent examples include: Transverse Oscillations, which uses receive apodization to create a laterally oscillating field which can be used for lateral displacement estimation [2], [3]; Vector Flow Mapping, which calculates the lateral velocity component by post-processing colour Doppler acquisitions [4]; Blood Speckle Tracking, which estimates the displacement of the speckle patterns arising from red blood cell back-scatter using block-matching [5]- [7]; and Echo-Particle Image Velocimetry (echoPIV -also known as ultrasound image velocimetry), which also tracks speckle patterns, but those arising from ultrasound contrast agent (UCA) microbubbles which have been injected intravenously into the blood stream [8]- [11].…”

Mitral Regurgitation—When One View Isn't Enough

“…15 Newer ultrasound imaging tools such as particle imaging velocimetry, vector flow imaging and blood speckle tracking hold promise to enhance our understanding of this complex lesion. [16][17][18] Despite these newer developments, MR will remain a challenge and it is unlikely that a diagnostic magic wand will emerge. Instead, we must still rely on a set of complementary tools and tricks that are available in the imaging magician's box.…”

Blood Flow Quantification with High-Frame-Rate, Contrast-Enhanced Ultrasound Velocimetry in Stented Aortoiliac Arteries: In Vivo Feasibility

“…This method was first adapted using a clinical ultrasound machine by (Kim et al 2004). However, the use of conventional, line-scanning ultrasound imaging resulted in underestimation of high velocities (Poelma 2017;Vos et al 2020). Recent echoPIV methods use planewave and diverging-wave ultrasound imaging to obtain several thousands of images per second.…”