IEEE Trans Biomed Eng. 2019 Dec;66(12):3426-3435. doi: 10.1109/TBME.2019.2905551. Epub 2019 Mar 18.
Most neurodegenerative diseases are highly linked with aging. The mechanical properties of the brain should be determined for predicting and diagnosing age-related brain diseases. A preclinical animal study is crucial for neurological disease research. However, estimation of the elasticity properties of different regions of mouse brains remains difficult because of the size of the brain. In this paper, high-frequency ultrasound elastography (HFUSE) based on shear wave imaging was proposed for mapping the stiffness of the mouse brain at different ages ex vivo.
For HFUSE, a 40-MHz ultrasound array transducer with an ultrafast ultrasound imaging system was used in this paper. The accuracy and resolution during HFUSE were determined through a mechanical testing system and by conducting phantom experiments.
In the experiments, the error in the elastic modulus measurement was approximately 10% on average, and the axial resolution was 248 μm. Animal testing was conducted using mice that were 4 (young aged) and 11 (middle aged) months old. The elasticity distributions of the cortex and hippocampus in the mouse brains were obtained through HFUSE.
The average shear moduli of the cortex and hippocampus were 3.84 and 2.33 kPa for the 4-month-old mice and 3.77 and 1.94 kPa for the 11-month-old mice, respectively. No statistical difference was observed in the cortex stiffness of mice of different ages. However, the hippocampus significantly softened with aging.
大多数神经退行性疾病与衰老高度相关。为了预测和诊断与年龄相关的脑部疾病，应确定大脑的机械性能。临床前动物研究对于神经疾病研究至关重要。然而，由于大脑的体积，很难估计不同区域的老鼠大脑的弹性特性。在本文中，提出了基于剪切波成像的高频超声弹性成像（HFUSE）来体外绘制不同年龄老鼠大脑的硬度。
在 HFUSE 中，本文使用了具有超快超声成像系统的 40MHz 超声阵列换能器。通过机械测试系统和进行的体模实验来确定 HFUSE 的准确性和分辨率。
在实验中，弹性模量测量的误差平均约为 10%，轴向分辨率为 248μm。通过对 4 个月（年轻）和 11 个月（中年）大的老鼠进行动物试验。通过 HFUSE 获得了老鼠大脑皮质和海马体的弹性分布。
4 个月大的老鼠的皮质和海马体的平均剪切模量分别为 3.84kPa 和 2.33kPa，而 11 个月大的老鼠的皮质和海马体的平均剪切模量分别为 3.77kPa 和 1.94kPa。不同年龄老鼠的皮质硬度没有统计学差异。然而，随着年龄的增长，海马体明显变软。
