Measurement of Flow Volume in the Presence of Reverse Flow with Ultrasound Speckle Decorrelation

Abstract

Direct measurement of volumetric flow rate in the cardiovascular system with ultrasound is valuable but has been a challenge because most current 2-D flow imaging techniques are only able to estimate the flow velocity in the scanning plane (in-plane). Our recent study demonstrated that high frame rate contrast ultrasound and speckle decorrelation (SDC) can be used to accurately measure the speed of flow going through the scanning plane (through-plane). The volumetric flow could then be calculated by integrating over the luminal area, when the blood vessel was scanned from the transverse view. However, a key disadvantage of this SDC method is that it cannot distinguish the direction of the through-plane flow, which limited its applications to blood vessels with unidirectional flow. Physiologic flow in the cardiovascular system could be bidirectional due to its pulsatility, geometric features, or under pathologic situations. In this study, we proposed a method to distinguish the through-plane flow direction by inspecting the flow within the scanning plane from a tilted transverse view. This method was tested on computer simulations and experimental flow phantoms. It was found that the proposed method could detect flow direction and improved the estimation of the flow volume, reducing the overestimation from over 100% to less than 15% when there was flow reversal. This method showed significant improvement over the current SDC method in volume flow estimation and can be applied to a wider range of clinical applications where bidirectional flow exists.

Renal blood flow and oxygenation

“…Consequently, traditional Doppler ultrasound measurements offer relatively low accuracy outside idealized settings [ 78 ]. Newer methods [ 79 ], e.g., ones based on a combination of high frame rate and speckle decorrelation [ 80 ], promise more reliable estimation of blood flow, but they have yet to be established in the clinic.…”

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

“…Zhou et al (2018) used this idea to measure blood flow in the abdominal aorta of a rabbit but they noted that precise perpendicular alignment to the flow was required to avoid bias, and the direction once again was not measurable. In further extension of the method, Zhou et al (2019c) described a tilt of the view angle with respect to the cross-section of the vessel so that the direction could also be determined using in-plane echo-PIV.…”