Xu Tiantian, Hozan Mohsen, Bashford Gregory R
Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Ultrasound Med Biol. 2014 May;40(5):931-7. doi: 10.1016/j.ultrasmedbio.2013.11.017. Epub 2014 Jan 22.
In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method across a field of view and combination with an appropriate axial flow estimator.
在先前的研究中，我们提出了利用散斑大小估计进行血流测量的方法，该方法基于这样的观察结果：如果血流方向与二维图像中电子控制的换能器线选择方向相同，那么对应于血液反射体（通常是红细胞）的散斑图案会拉伸（即“模糊”），从而在单个图像帧内估计血流的横向分量。在这项观察性研究中，我们研究了使用散斑大小估计进行超声血流速度测量的临床可行性，并将其与从人类患者体内收集的颈动脉血流数据的传统频谱多普勒测量方法进行了比较。招募了10名患者（6名男性，4名女性）。使用安塔尔超声成像系统以交错方式（交替进行多普勒和B模式A线）收集右侧颈动脉血流数据，并通过Axius超声研究接口传输到个人计算机。扫描速度为77厘米/秒，从每个受试者收集4秒的血流数据间隔，以覆盖三到五个完整的心动周期。同时收集传统频谱多普勒数据，以便与散斑大小估计得出的结果进行比较。结果表明，如果扫描速度大于或等于血流速度，两种方法测量的收缩期峰值速度具有可比性（在±10%以内）。当扫描速度慢于收缩期峰值速度时，散斑拉伸法渐近于扫描速度。因此，散斑拉伸法能够准确测量纯横向血流，而传统多普勒方法则无法做到。此外，对散斑大小估计和彩色多普勒方法在计算复杂度和数据采集时间方面的初步比较表明，使用散斑大小估计进行血流速度估计可能会节省时间。需要进一步研究以计算散斑拉伸法在整个视野范围内的结果，并与合适的轴向血流估计器相结合。
