磁共振弹性成像频率依赖性和非依赖性参数显示大脑硬度在老年受试者中加速降低。
MR elastography frequency-dependent and independent parameters demonstrate accelerated decrease of brain stiffness in elder subjects.
机构信息
Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China.
Department of Radiology, Stanford University, 300 Pasteur Drive, Room S047, Stanford, CA, 94305-5105, USA.
出版信息
Eur Radiol. 2020 Dec;30(12):6614-6623. doi: 10.1007/s00330-020-07054-7. Epub 2020 Jul 18.
OBJECTIVES
To analyze the mechanical properties in different regions of the brain in healthy adults in a wide age range: 26 to 76 years old.
METHODS
We used a multifrequency magnetic resonance elastography (MRE) protocol to analyze the effect of age on frequency-dependent (storage and loss moduli, G' and G″, respectively) and frequency-independent parameters (μ, μ, and η, as determined by a standard linear solid model) of the cerebral parenchyma, cortical gray matter (GM), white matter (WM), and subcortical GM structures of 46 healthy male and female subjects. The multifrequency behavior of the brain and frequency-independent parameters were analyzed across different age groups.
RESULTS
The annual change rate ranged from - 0.32 to - 0.36% for G' and - 0.43 to - 0.55% for G″ for the cerebral parenchyma, cortical GM, and WM. For the subcortical GM, changes in G' ranged from - 0.18 to - 0.23%, and G″ changed - 0.43%. Interestingly, males exhibited decreased elasticity, while females exhibited decreased viscosity with respect to age in some regions of subcortical GM. Significantly decreased values were also found in subjects over 60 years old.
CONCLUSION
Values of G' and G″ at 60 Hz and the frequency-independent μ of the caudate, putamen, and thalamus may serve as parameters that characterize the aging effect on the brain. The decrease in brain stiffness accelerates in elderly subjects.
KEY POINTS
• We used a multifrequency MRE protocol to assess changes in the mechanical properties of the brain with age. • Frequency-dependent (storage moduli G' and loss moduli G″) and frequency-independent (μ, μ, and η) parameters can bequantitatively measured by our protocol. • The decreased value of viscoelastic properties due to aging varies in different regions of subcortical GM in males and females, and the decrease in brain stiffness is accelerated in elderly subjects over 60 years old.
目的
分析年龄跨度较大（26 岁至 76 岁）的健康成年人大脑不同区域的力学特性。
方法
我们使用多频磁共振弹性成像（MRE）方案来分析年龄对脑实质、皮质灰质（GM）、白质（WM）和皮质下 GM 结构的频率相关（存储和损耗模量，G'和 G″）和频率无关（μ、μ和η，由标准线性固体模型确定）参数的影响。对 46 名健康男性和女性受检者进行了多频脑和频率无关参数的分析。
结果
脑实质、皮质 GM 和 WM 的 G'和 G″的年变化率分别为 -0.32%至-0.36%和-0.43%至-0.55%。对于皮质下 GM，G'的变化范围为-0.18%至-0.23%，G″的变化范围为-0.43%。有趣的是，在一些皮质下 GM 区域，男性的弹性降低，而女性的粘性随着年龄的增长而降低。在 60 岁以上的受试者中，也发现了明显的降低值。
结论
60 Hz 时的 G'和 G″值以及尾状核、壳核和丘脑的频率无关的μ值可作为特征化大脑老化效应的参数。大脑硬度的降低在老年患者中加速。
重点
我们使用多频 MRE 方案评估大脑机械特性随年龄的变化。
频率相关（存储模量 G'和损耗模量 G″）和频率无关（μ、μ和η）参数可以通过我们的方案进行定量测量。
由于老化导致的粘弹性特性的降低在男性和女性的皮质下 GM 不同区域有所不同，60 岁以上的老年患者大脑硬度的降低加速。
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