Parizel P M, Van Goethem J W, van den Hauwe L, Dillen C, Verlooy J, Cosyns P, De Schepper A M
Department of Radiology, Universitair Ziekenhuis Antwerpen (University of Antwerp), Wilrijkstraat 10, B-2650 Edegem, Belgium.
Eur Radiol. 1998;8(6):960-5. doi: 10.1007/s003300050496.
Even in patients with closed head trauma, brain parenchyma can be severely injured due to disruption of axonal fibers by shearing forces during acceleration, deceleration, and rotation of the head. In this article we review the spectrum of imaging findings in patients with diffuse axonal injuries (DAI) after closed head trauma. Knowledge of the location and imaging characteristics of DAI is important to radiologists for detection and diagnosis. Common locations of DAI include: cerebral hemispheric gray-white matter interface and subcortical white matter, body and splenium of corpus callosum, basal ganglia, dorsolateral aspect of brainstem, and cerebellum. In the acute phase, CT may show punctate hemorrhages. The true extent of brain involvement is better appreciated with MR imaging, because both hemorrhagic and non-hemorrhagic lesions (gliotic scars) can be detected. The MR appearance of DAI lesions depends on several factors, including age of injury, presence of hemorrhage or blood-breakdown products (e. g., hemosiderin), and type of sequence used. Technical aspects in MR imaging of these patients are discussed. Non-hemorrhagic lesions can be detected with fluid attenuated inversion recovery (FLAIR), proton-density-, or T2-weighted images, whereas gradient echo sequences with long TE increase the visibility of old hemorrhagic lesions.
即使在闭合性颅脑外伤患者中，由于头部加速、减速和旋转过程中的剪切力导致轴突纤维断裂，脑实质也可能受到严重损伤。在本文中，我们回顾了闭合性颅脑外伤后弥漫性轴索损伤（DAI）患者的影像学表现谱。了解DAI的位置和影像学特征对放射科医生进行检测和诊断很重要。DAI的常见位置包括：大脑半球灰白质界面和皮质下白质、胼胝体和胼胝体压部、基底节、脑干背外侧以及小脑。在急性期，CT可能显示点状出血。磁共振成像（MR）能更好地显示脑损伤的真实范围，因为出血性和非出血性病变（胶质瘢痕）均可被检测到。DAI病变的MR表现取决于多个因素，包括损伤时间、出血或血液分解产物（如含铁血黄素）的存在以及所使用的序列类型。本文还讨论了这些患者MR成像的技术要点。非出血性病变可通过液体衰减反转恢复（FLAIR）序列、质子密度加权或T2加权图像检测到，而长回波时间的梯度回波序列可提高陈旧性出血性病变的可见性。
