Microscopic magnetic resonance elastography (μMRE)
Microscopic magnetic resonance elastography (μMRE)
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DOI：
10.1002/mrm.20584
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发表时间：
2005-09-01
影响因子：
3.3
通讯作者：
Magin, RL
中科院分区：
文献类型：
--
作者：
Othman, SF;Xu, HH;Magin, RL
磁共振弹性成像（MRE）扩展到微观尺度的图像低频声剪切波（通常小于1 kHz）在软凝胶和软生物组织与高空间分辨率（34 μ m × 34 μ m × 500 μ m）。显微镜MRE（μ MRE）应用于琼脂糖凝胶模型，青蛙卵母细胞，和组织工程脂肪和成骨结构。分析样品中的低振幅剪切波图案允许以高空间分辨率识别材料刚度和粘性损耗特性（复合剪切刚度）。μ MRE实验在11.74 T下在56 mm垂直孔磁体中进行，该磁体具有10 mm直径× 75 mm长度的圆柱形空间，可用于弹性成像系统。使用压电换能器和高电容负载放大器在550-585 Hz下产生声信号。剪切波运动与MR脉冲序列同步施加。对于0.5 mm的典型切片厚度，视野（FOV）范围为4至14 mm。增加琼脂糖凝胶浓度导致剪切弹性和剪切粘度增加。剪切波运动通过青蛙卵母细胞核传播，从而能够测量其剪切刚度，并且体外剪切波图像显示了成脂组织工程构建体和成骨组织工程构建体之间的对比。μ MRE的进一步发展应使其能够用于表征更硬的材料（例如，聚合物、复合材料、关节软骨）并以高分辨率评估发育组织的机械性能。
Magnetic resonance elastography (MRE) was extended to the microscopic scale to image low-frequency acoustic shear waves (typically less than 1 kHz) in soft gels and soft biological tissues with high spatial resolution (34 mu m x 34 mu m x 500 mu m). Microscopic MRE (mu MRE) was applied to agarose gel phantoms, frog oocytes, and tissue-engineered adipogenic and osteogenic constructs. Analysis of the low-amplitude shear wave pattern in the samples allowed the material stiffness and viscous loss properties (complex shear stiffness) to be identified with high spatial resolution. mu MRE experiments were conducted at 11.74 T in a 56-mm vertical bore magnet with a 10 mm diameter x 75 mm length cylindrical space available for the elastography imaging system. The acoustic signals were generated at 550-585 Hz using a piezoelectric transducer and high capacitive loading amplifier. Shear wave motion was applied in synchrony with the MR pulse sequence. The field of view (FOV) ranged from 4 to 14 mm for a typical slice thickness of 0.5 mm. Increasing the agarose gel concentration resulted in an increase in shear elasticity and shear viscosity. Shear wave motion propagated through the frog oocyte nucleus, enabling the measurement of its shear stiffness, and in vitro shear wave images displayed contrast between adipogenic and osteogenic tissue-engineered constructs. Further development of mu MRE should enable its use in characterizing stiffer materials (e.g., polymers, composites, articular cartilage) and assessing with high resolution the mechanical properties of developing tissues.