超声二维斑点追踪技术分析小鼠腹主动脉血管壁运动学特征

Quantifying kinematic characteristics of abdominal aorta wall using two-dimensional speckle tracking ultrasound in mice

目的探讨超高分辨率小动物超声影像系统二维斑点追踪技术分析小鼠腹主动脉血管壁运动学特征的方法。方法选用6只正常8周龄C57B1/6J雄性小鼠及6只60周龄载脂蛋白E(apolipoprotein E)基因敲除小鼠(ApoE-/-),应用超高分辨率小动物专用超声影像系统及40 MHz探头,M型超声测定小鼠腹主动脉内膜-中膜厚度(IMT),二维斑点追踪技术检测血管平均面积、血管平均直径及面积变化率(area percent spread)和直径变化率(diameter percent spread)等指标,以及腹主动脉前壁和后壁的运动速度、位移及腹主动脉整体径向应变(global radial strain)等运动学特征指标。结果应用超高分辨率小动物超声影像系统能获得清晰的小鼠腹主动脉影像。超声结果提示与正常小鼠相比,ApoE-/-小鼠内-中膜厚度增加(0.05±0.01 mm比0.08±0.01 mm),面积变化率(38.91±5.03%比19.00±3.74%)和直径变化率(19.55±2.46%比9.75±1.71%)下降;腹主动脉前壁纵向径向速度(-5.11±1.47 mm/s比-2.97±0.77 mm/s)和后壁纵向径向速度(-3.15±1.14mm/s比-1.76±0.64 mm/s)下降;前壁纵向径向位移(-73.60±11.61μm比-38.29±10.09μm)和后壁纵向径向位移(-46.62±10.97μm比-21.56±5.07μm)减低,血管壁整体径向应变降低(47.25±7.06%比21.00±4.25%),差异有统计学意义(P <0.05)。前壁纵向切向速度(2.78±1.24 mm/s比2.40±0.58 mm/s)、后壁纵向切向速度(2.02±1.14 mm/s比1.79±0.75 mm/s)以及前壁纵向切向位移(35.82±18.00μm比33.01±12.37μm)、后壁纵向切向位移(28.83±16.09μm比26.24±9.53μm)差异无统计学意义(P>0.05)。结论应用二维斑点追踪技术评价小鼠腹主动脉血管壁运动学特征方法是可行的,可作为分析实验小动物动脉功能的新方法。

Objective To quantify kinematic characteristics of abdominal aorta wall using two-dimensional （2-D） speckle tracking （ST） ultrasound （US） in mice. Methods Six 8-week-old normal C57B1/6J male mice and six 60-week-old apolipoprotein E gene-removed （ApoE / ） mice underwent 40 MHz US scan （Vevo 2100 imaging System; FUJIFILM VisuaISonics, Inc., USA） of their abdominal aorta. Conventional and 2-D ST US was performed to evaluate the peak strain, displacement and velocity. Results Compared with, ApoE/ mice had increased intima-media thickness （IMT; 0.08±0.01 mm） but decreased area percent spread （19.00±3.74%）, and diameter percent spread （9.75%±1.71%） compared to C57BI/6J mice （0.05±0.01 mm, 38.91±5.03%, 19.55% ±2.46%）. In ApoE^-/- mice, the longitudinal radial velocities and displacements of the anterior wall （-5.11±1.47 mm/s, -73.60± 11.61μm）, posterior wall （-3.15±1.14 mm/s, -46.62±10.97μm）, and the global radial strain （21.00%±4.25%） were all significantly lower （P〈0.05） than that of C57B1/6J mice （-2.97±0.77 mm/s, -38.29±10.09μm, -1.76±0.64 mm/s, -21.56±5.07μm, 47.25%±7.06 %）. There was no significant difference （P〉0.05） between ApoE / mice in the longitudinal tangential velocities of the anterior wall （2.78±1.24 mm/s）, longitudinal tangential velocities of the posterior wall （2.02±1.14 mm/s）, longitudinal tangential displacement of the anterior wall （35.82±18.00μm）, longitudinal tangential displacement of the posterior wall （28.83±16.09μm） and that of C57B1/6J mice （2.40±0.58 mm/s, 1.79±0.75 mm/s, 33.01±12.37μm, 26.24±9.53μm）. Conclusion 2-D ST US is feasi-ble for evaluating the kinematic characteristics of the abdominal aorta in mice.