Sidaros Annette, Engberg Aase W, Sidaros Karam, Liptrot Matthew G, Herning Margrethe, Petersen Palle, Paulson Olaf B, Jernigan Terry L, Rostrup Egill
Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Department 340, 2650 Hvidovre, Denmark.
Brain. 2008 Feb;131(Pt 2):559-72. doi: 10.1093/brain/awm294. Epub 2007 Dec 14.
Diffusion tensor imaging (DTI) has been proposed as a sensitive biomarker of traumatic white matter injury, which could potentially serve as a tool for prognostic assessment and for studying microstructural changes during recovery from traumatic brain injury (TBI). However, there is a lack of longitudinal studies on TBI that follow DTI changes over time and correlate findings with long-term clinical outcome. We performed a prospective longitudinal study of 30 adult patients admitted for subacute rehabilitation following severe traumatic brain injury. DTI and conventional MRI were acquired at mean 8 weeks (5-11 weeks), and repeated in 23 of the patients at mean 12 months (9-15 months) post-trauma. Using a region-of-interest-based approach, DTI parameters were compared to those of healthy matched controls, scanned during the same time period and rescanned with a similar interval as that of patients. At the initial scan, fractional anisotropy was reduced in all the investigated white matter regions in patients compared to controls (P <or= 0.01) due to decreased diffusivity parallel (lambda(parallel)) and increased diffusivity perpendicular (lambda(perpendicular)) to axonal fibre direction. Fractional anisotropy in the cerebral peduncle correlated with approximately 1 year Glasgow outcome scale score (r = 0.60, P<0.001) and in this sample predicted dichotomized outcome with 76% accuracy when taken alone, and with 100% accuracy in combination with clinical evaluation by functional independence measure at the time of the first scan. At follow-up DTI, fractional anisotropy in patients had increased in the internal capsule and in centrum semiovale (P <or= 0.01) due to an interval increase of lambda(parallel) with unchanged lambda(perpendicular). In these regions, fractional anisotropy and lambda( parallel) reached normal or supranormal levels, primarily in patients with favourable outcome. In the cerebral peduncle and in corpus callosum, lambda(parallel) and lambda(perpendicular) both increased during the scan interval and, particularly in patients with unfavourable outcome, fractional anisotropy remained depressed. No significant DTI parameter changes over time were found in controls, or in CSF of patients. These findings support that DTI is a clinically relevant biomarker in TBI, which may have prognostic value and also might serve as a tool for revealing changes in the neural tissue during recovery.
扩散张量成像（DTI）已被提议作为创伤性白质损伤的一种敏感生物标志物，它有可能作为一种预后评估工具，用于研究创伤性脑损伤（TBI）恢复过程中的微观结构变化。然而，缺乏关于TBI的纵向研究，即跟踪DTI随时间的变化并将研究结果与长期临床结果相关联。我们对30例因重度创伤性脑损伤而接受亚急性康复治疗的成年患者进行了一项前瞻性纵向研究。在平均8周（5 - 11周）时进行DTI和传统MRI检查，并在23例患者中于创伤后平均12个月（9 - 15个月）时重复检查。采用基于感兴趣区域的方法，将DTI参数与健康匹配对照组的参数进行比较，对照组在同一时间段进行扫描，并以与患者相似的时间间隔重新扫描。在初次扫描时，与对照组相比，患者所有被研究的白质区域的分数各向异性均降低（P≤0.01），这是由于平行于轴突纤维方向的扩散率（λ平行）降低以及垂直于轴突纤维方向的扩散率（λ垂直）增加所致。大脑脚的分数各向异性与大约1年的格拉斯哥预后量表评分相关（r = 0.60，P<0.001），在该样本中，单独使用时预测二分法结果的准确率为76%，与初次扫描时通过功能独立性测量进行的临床评估相结合时准确率为100%。在随访DTI时，患者内囊和半卵圆中心的分数各向异性增加（P≤0.01），这是由于λ平行增加而λ垂直不变。在这些区域，分数各向异性和λ平行达到正常或超正常水平，主要见于预后良好的患者。在大脑脚和胼胝体中，λ平行和λ垂直在扫描间隔期间均增加，特别是在预后不良的患者中，分数各向异性仍然降低。在对照组或患者的脑脊液中未发现DTI参数随时间有显著变化。这些发现支持DTI是TBI中一种与临床相关的生物标志物，它可能具有预后价值，也可能作为揭示恢复过程中神经组织变化的工具。
