Shehada R E, Cobbold R S, Mo L Y
Institute of Biomedical Engineering, University of Toronto, Canada.
Biorheology. 1994 Jan-Feb;31(1):115-35. doi: 10.3233/bir-1994-31110.
Ultrasound B-mode imaging (7 MHz) was used to measure blood echogenicity and velocity profiles simultaneously as they developed with axial distance for a steady flow of 28% hematocrit whole blood flowing in a long (> 60 D) large diameter (D = 2.54 cm) tube. At selected sites along the flow axis, velocity profiles were measured using block matching (cross correlation) between successive digitized images with a known time separation; from these shear rate profiles were calculated. The corresponding echogenicity profiles were also determined by averaging the digitized images. It was found that over a range of low shear rates, the echogenicity is enhanced in a manner similar to the previously reported influence on aggregation. Evidence is presented confirming the important role of aggregation in controlling the echogenicity. The transient effects of abrupt flow stoppage were studied and shown to provide useful insights into aggregation kinetics. Based on the above results, a detailed explanation is provided of the echogenicity variations seen in B-mode ultrasound images of slow-moving blood.
使用超声B型成像（7兆赫兹），在一根长（>60D）、大直径（D = 2.54厘米）的管子中，对血细胞比容为28%的全血稳定流动时随轴向距离变化的血液回声性和速度剖面进行同步测量。在流动轴线上的选定位置，利用具有已知时间间隔的连续数字化图像之间的块匹配（互相关）测量速度剖面；由此计算出剪切速率剖面。相应的回声性剖面也通过对数字化图像求平均值来确定。研究发现，在一系列低剪切速率范围内，回声性增强的方式类似于先前报道的对聚集的影响。有证据证实了聚集在控制回声性方面的重要作用。研究了突然停止流动的瞬态效应，并表明其能为聚集动力学提供有用的见解。基于上述结果，对在缓慢流动血液的B型超声图像中看到的回声性变化给出了详细解释。
