Department of Neurosurgery, No. 3 People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 280 Mo-He Road, Shanghai 201900, China.
Eur J Neurosci. 2011 Mar;33(5):933-45. doi: 10.1111/j.1460-9568.2010.07573.x.
Diffuse axonal injury (DAI) is the predominant effect of severe traumatic brain injury and contributes significantly to neurological deficits. However, it is difficult to diagnose or characterize non-invasively with conventional imaging. Our study provides significant validation of a visual and statistical diffusion tensor imaging (DTI) technique as compared with pathological and electron microscopic study in a rat DAI model at multiple predilection sites and time points following trauma. Two DTI parameters, fractional anisotropy (FA) and axial diffusivity (AD), were significantly reduced from 12 h to 5 days post-trauma, corresponding to pathological axonal injury. At 7 days post-trauma, FA remained decreased, whereas AD pseudo-normalized and radial diffusivity increased. The temporal alterations in DTI parameters were observed in multiple predilection sites, and the extent of the changes in these parameters correlated significantly with the severity of histologically visualized axonal injury, as assessed by integrated optical density of immunochemically stained injured axons with quantitative stereology. Although anatomical T2-weighted magnetic resonance images showed no abnormal signals in microscopic lesions, we detected and characterized axonal injury directly by DTI at each time point. These results demonstrate that DTI has significant potential as a non-invasive tool with which to quantitatively diagnose and evaluate microstructural injury in the experimental and clinical assessment of DAI. This method can assist in accurate evaluation of the extent of axonal injury, detection of severe predilection foci, determination of approximate time of injury, and monitoring of the pathogenic condition at the early post-injury stage.
弥漫性轴索损伤（DAI）是严重创伤性脑损伤的主要影响因素，对神经功能缺损有重要贡献。然而，常规影像学检查难以对其进行诊断或进行无创特征分析。本研究在创伤后多个易损部位和时间点，通过与病理和电子显微镜研究进行比较，对一种可视且统计性的弥散张量成像（DTI）技术进行了重要验证，该技术可用于大鼠 DAI 模型。在创伤后 12 小时至 5 天，两个 DTI 参数，即各向异性分数（FA）和轴向弥散度（AD），均显著降低，与病理轴索损伤相对应。在创伤后 7 天，FA 仍然降低，而 AD 假性正常化，放射弥散度增加。DTI 参数的时间变化发生在多个易损部位，这些参数的变化程度与免疫化学染色损伤轴突的积分光密度的定量立体学评估的病理上可视化轴索损伤的严重程度显著相关。尽管解剖 T2 加权磁共振图像在微观病变中未显示异常信号，但我们在每个时间点都通过 DTI 直接检测和特征分析了轴索损伤。这些结果表明，DTI 具有作为一种非侵入性工具的显著潜力，可用于定量诊断和评估 DAI 的实验和临床评估中的微观结构损伤。这种方法可以帮助准确评估轴索损伤的程度、检测严重易损焦点、确定损伤的大致时间以及在损伤后早期阶段监测发病情况。
