Reduction of Diffusion-Weighted Imaging Contrast of Acute Ischemic Stroke at Short Diffusion Times
Reduction of Diffusion-Weighted Imaging Contrast of Acute Ischemic Stroke at Short Diffusion Times
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DOI：
10.1161/strokeaha.115.008815
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发表时间：
2015-08-01
期刊：
影响因子：
8.3
通讯作者：
Beaulieu, Christian
中科院分区：
文献类型：
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作者：
Baron, Corey Allan;Kate, Mahesh;Beaulieu, Christian
背景和目的-组织水的弥散加权成像（DWI）是急性脑缺血的敏感和特异性指标，在卒中病灶核心急性观察到组织水的弥散减少。虽然这些扩散的变化一直归因于细胞肿胀，生物物理机制的确切性质仍然uncertaints. Methods扩散减少中风后的潜在原因进行了研究，使用先进的DWI技术，振荡梯度自旋回波DWI，这使得扩散时间短得多，并且可以提高微米级结构改变的特异性。在急性缺血性卒中患者的白色病变中，使用振荡梯度自旋回波DWI的弥散测量值仅降低8%，而使用标准DWI的弥散测量值降低37%。神经突串珠最近被提出作为缺血性中风后扩散变化的机制，有一些离体证据。要探讨是否串珠可能会导致这种差异的结果，模拟串珠圆柱体和轴突肿胀进行，产生良好的协议与experiment. Conclusions短扩散时间导致显着降低扩散对比度的人类中风。模拟暗示了神经元串珠和轴突肿胀的组合作为导致中风后表观扩散系数降低的关键结构变化。
Background and Purpose-Diffusion-weighted imaging (DWI) of tissue water is a sensitive and specific indicator of acute brain ischemia, where reductions of the diffusion of tissue water are observed acutely in the stroke lesion core. Although these diffusion changes have been long attributed to cell swelling, the precise nature of the biophysical mechanisms remains uncertain.Methods-The potential cause of diffusion reductions after stroke was investigated using an advanced DWI technique, oscillating gradient spin-echo DWI, that enables much shorter diffusion times and can improve specificity for alterations of structure at the micron level.Results-Diffusion measurements in the white matter lesions of patients with acute ischemic stroke were reduced by only 8% using oscillating gradient spin-echo DWI, in contrast to a 37% decrease using standard DWI. Neurite beading has recently been proposed as a mechanism for the diffusion changes after ischemic stroke with some ex vivo evidence. To explore whether beading could cause such differential results, simulations of beaded cylinders and axonal swelling were performed, yielding good agreement with experiment.Conclusions-Short diffusion times result in dramatically reduced diffusion contrast of human stroke. Simulations implicate a combination of neuronal beading and axonal swelling as the key structural changes leading to the reduced apparent diffusion coefficient after stroke.