用散射理论量化轴突损伤，实现脑损伤早期无创检测。
Scattering approach to diffusion quantifies axonal damage in brain injury
- 基于散射理论建模水分子在轴突中的扩散行为。
- 仅需秒级计算即可预测数千根轴突的损伤指标。
- 适用于创伤性脑损伤等神经疾病，提供客观生物标志物。
早期诊断和无创监测神经系统疾病需要对微米尺度的细胞水平改变敏感，这些变化远早于医学影像毫米级分辨率可观察到的体积变化。轴突肿胀或珠状结构等形态改变常见于神经系统疾病、发育及衰老过程。本文揭示了时变扩散磁共振成像（dMRI）对微米尺度轴突结构紊乱的高度敏感性。散射理论识别出决定水分子沿轴突扩散动态的两个参数：平均倒数横截面积与长程横截面波动方差。该理论框架使我们能在秒级内预测大鼠创伤性脑损伤模型中数万根轴突的损伤指标，而无需数月模拟；且经离体dMRI验证。本方法连接了微米与毫米尺度的分辨率鸿沟，为多种神经系统疾病提供定量、客观的生物标志物。
原文摘要 · Abstract (English)
Early diagnosis and noninvasive monitoring of neurological disorders require sensitivity to elusive cellular-level alterations that occur much earlier than volumetric changes observable with the millimeter-resolution of medical imaging modalities. Morphological changes in axons, such as axonal varicosities or beadings, are observed in neurological disorders, as well as in development and aging. Here, we reveal the sensitivity of time-dependent diffusion MRI (dMRI) to the structurally disordered axonal morphology at the micrometer scale. Scattering theory uncovers the two parameters that determine the diffusive dynamics of water along axons: the average reciprocal cross-section and the variance of long-range cross-sectional fluctuations. This theoretical development allows us to predict dMRI metrics sensitive to axonal alterations over tens of thousands of axons in seconds rather than months of simulations in a rat model of traumatic brain injury, and is corroborated with ex vivo dMRI. Our approach bridges the gap between micrometers and millimeters in resolution, offering quantitative and objective biomarkers applicable to a broad spectrum of neurological disorders.
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