Hansen Kristoffer L, Udesen Jesper, Thomsen Carsten, Jensen Jørgen A, Nielsen Michael B
Department of Radiology, University Hospital of Copenhagen, Denmark.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Jan;56(1):91-100. doi: 10.1109/TUFFC.2009.1008.
Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound beam direction. This implies that a Doppler angle under examination close to 90 degrees results in unreliable information about the true blood direction and blood velocity. The novel method transverse oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance phase contrast angiography (MRA) by comparing in vivo measurements of stroke volume. Eleven healthy volunteers were included in this prospective study. From the obtained data sets recorded with the 2 modalities, vector velocity sequences were constructed and stroke volume calculated. Angle of insonation was approximately 90 degrees for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p < 0.01) with the equation for the line of regression: MRA = 1.1.TO-0.4. A Bland-Altman plot was additionally constructed where the mean difference was 0.2 ml with limits of agreement at -1.4 ml and 1.9 ml. The results indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative velocity information.
传统的用于估计血流速度的多普勒方法仅能估计沿超声束方向的速度分量。这意味着，当检测时的多普勒角度接近90度时，所得到的关于真实血流方向和血流速度的信息并不可靠。一种新的横向振荡（TO）方法，它结合了扫描平面内轴向和横向速度分量的估计值，使得无论多普勒角度如何，都能够估计出血流的矢量速度。本研究通过比较心搏量的体内测量结果，用磁共振相位对比血管造影术（MRA）对TO方法进行评估。11名健康志愿者被纳入这项前瞻性研究。从用这两种方式记录得到的数据集中，构建矢量速度序列并计算心搏量。TO测量时的声束入射角度约为90度。TO估计的心搏量与MRA之间的相关性为0.91（p < 0.01），回归线方程为：MRA = 1.1×TO - 0.4。另外还构建了布兰德-奥特曼图，平均差异为0.2 ml，一致性界限为-1.4 ml和1.9 ml。结果表明，使用所提出的与角度无关的二维矢量速度方法能够在体内获得可靠的矢量速度估计值。通过避免角度伪像，TO方法可以成为传统多普勒系统的一种有用替代方法，从而提供定量的速度信息。
