Microvasculature alters the dispersion properties of shear waves - a multi-frequency MR elastography study
Microvasculature alters the dispersion properties of shear waves - a multi-frequency MR elastography study
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DOI：
10.1002/nbm.3438
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发表时间：
2015-12-01
影响因子：
2.9
通讯作者：
Sinkus, Ralph
中科院分区：
文献类型：
--
作者：
Juge, Lauriane;Petiet, Anne;Sinkus, Ralph
磁共振弹性成像（MRE）使用宏观剪切波传播来量化软组织的机械特性。微观障碍物能够影响剪切波的宏观色散特性。由于疾病或治疗可以改变血管结构的机械完整性和组织，如果血管代表波散射的源，则MRE应该能够感测到这些变化。为了验证这一点，使用主动脉环模型进行了MRE，以量化由于存在血管增生而导致的剪切波速度c（s）的变化。使用7特斯拉MR扫描仪（Bruker，PharmaScan）对包含在Matrigel基质中的18个大鼠主动脉碎片（n=6，无生长，n=6，径向生长程度类似于600 μ m，n=6，径向生长程度类似于850 μ m）成像。除多频率MRE（nu = 100、115、125、135和150 Hz）外，还采集了高分辨率解剖图像。在包围主动脉的近似于900 μ m厚度的环内测量平均c（s），并将其标准化为相应基质胶的c（s 0）。频率依赖性拟合到类似于nu（y）的幂律模型c（s）。扫描后，进行光学显微镜检查以观察生长物。结果表明，在存在血管增生的情况下，（1）三个最高频率的标准化c（s）显著增加（Kruskal-Wallis检验，125 Hz时P = 0.0002，135 Hz时P = 0.002，150 Hz时P = 0.003），但两个最低值不存在（Kruskal-Wallis检验，在100 Hz下P = 0.63，在115 Hz下P = 0.87），和（2）标准化c（s）遵循幂律行为，在不存在血管增生的情况下未见（ANOVA检验，P < 0.0001）。这些结果表明，血管生长物作为微障碍物改变传播的剪切波的色散关系，MRE可以提供有关微血管变化的有价值的信息。版权所有（C）2015约翰威利父子有限公司
Magnetic Resonance Elastography (MRE) uses macroscopic shear wave propagation to quantify mechanical properties of soft tissues. Micro-obstacles are capable of affecting the macroscopic dispersion properties of shear waves. Since disease or therapy can change the mechanical integrity and organization of vascular structures, MRE should be able to sense these changes if blood vessels represent a source for wave scattering. To verify this, MRE was performed to quantify alteration of the shear wave speed c(s) due to the presence of vascular outgrowths using an aortic ring model. Eighteen fragments of rat aorta included in a Matrigel matrix (n=6 without outgrowths, n=6 with a radial outgrowth extent of similar to 600 mu m and n=6 with similar to 850 mu m) were imaged using a 7 Tesla MR scanner (Bruker, PharmaScan). High resolution anatomical images were acquired in addition to multi-frequency MRE (nu = 100, 115, 125, 135 and 150 Hz). Average c(s) was measured within a ring of similar to 900 mu m thickness encompassing the aorta and were normalized to c(s0) of the corresponding Matrigel. The frequency dependence was fit to the power law model c(s) similar to nu(y). After scanning, optical microscopy was performed to visualize outgrowths. Results demonstrated that in presence of vascular outgrowths (1) normalized c(s) significantly increased for the three highest frequencies (Kruskal-Wallis test, P = 0.0002 at 125 Hz and P = 0.002 at 135 Hz and P = 0.003 at 150 Hz) but not for the two lowest (Kruskal-Wallis test, P = 0.63 at 100 Hz and P = 0.87 at 115 Hz), and (2) normalized c(s) followed a power law behavior not seen in absence of vascular outgrowths (ANOVA test, P < 0.0001). These results showed that vascular outgrowths acted as micro-obstacles altering the dispersion relationships of propagating shear waves and that MRE could provide valuable information about microvascular changes. Copyright (C) 2015 John Wiley & Sons, Ltd.