There is a critical need for understanding the progression of neuropathology in blast-induced traumatic brain injury using valid animal models to develop diagnostic approaches. In the present study, we used diffusion imaging and magnetic resonance (MR) morphometry to characterize axonal injury in white matter structures of the rat brain following a blast applied via blast tube to one side of the brain. Diffusion tensor imaging was performed on acute and subacute phases of pathology from which fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated for corpus callosum (CC), cingulum bundle, and fimbria. Ventricular volume and CC thickness were measured. Blast-injured rats showed temporally varying bilateral changes in diffusion metrics indicating persistent axonal pathology. Diffusion changes in the CC suggested vasogenic edema secondary to axonal injury in the acute phase. Axonal pathology persisted in the subacute phase marked by cytotoxic edema and demyelination which was confirmed by ultrastructural analysis. The evolution of pathology followed a different pattern in the cingulum bundle: axonal injury and demyelination in the acute phase followed by cytotoxic edema in the subacute phase. Spatially, structures close to midline were most affected. Changes in the genu were greater than in the body and splenium; the caudal cingulum bundle was more affected than the rostral cingulum. Thinning of CC and ventriculomegaly were greater only in the acute phase. Our results reveal the persistent nature of blast-induced axonal pathology and suggest that diffusion imaging may have potential for detecting the temporal evolution of blast injury.

中文翻译：

---

扩散张量成像检测爆炸诱发的外伤性脑损伤胼胝体的急性和亚急性变化。

迫切需要使用有效的动物模型来开发诊断方法来了解爆炸引起的创伤性脑损伤的神经病理学进展。在本研究中，我们使用扩散成像和磁共振 (MR) 形态测量法来表征通过爆炸管施加到大脑一侧的爆炸后大鼠大脑白质结构中的轴突损伤。在病理的急性和亚急性期进行扩散张量成像，从中计算胼胝体 (CC)、扣带束和伞毛的各向异性分数、平均扩散率、轴向扩散率和径向扩散率。测量心室容积和 CC 厚度。爆炸损伤的大鼠在扩散指标中显示出随时间变化的双边变化，表明持续的轴突病理。CC 中的弥散变化表明急性期继发于轴索损伤的血管源性水肿。轴突病理在亚急性期持续存在，以细胞毒性水肿和脱髓鞘为标志，超微结构分析证实了这一点。扣带束的病理学演变遵循不同的模式：急性期轴突损伤和脱髓鞘，然后是亚急性期细胞毒性水肿。在空间上，靠近中线的结构受到的影响最大。膝部的变化大于身体和脾脏的变化；尾部扣带束比头端扣带束受到的影响更大。CC 变薄和脑室扩大仅在急性期更大。