Li Yang, Liu Kaijun, Li Chang, Guo Yu, Fang Jingqin, Tong Haipeng, Tang Yi, Zhang Junfeng, Sun Jinju, Jiao Fangyang, Zhang Qianhui, Jin Rongbing, Xiong Kunlin, Chen Xiao
Department of Nuclear Medicine, Daping Hospital, Army Medical University, Chongqing, China.
Department of Radiology, Daping Hospital, Army Medical University, Chongqing, China.
Front Neurosci. 2021 Mar 18;15:593723. doi: 10.3389/fnins.2021.593723. eCollection 2021.
A majority of blast-induced mild traumatic brain injury (mTBI) patients experience persistent neurological dysfunction with no findings on conventional structural MR imaging. It is urgent to develop advanced imaging modalities to detect and understand the pathophysiology of blast-induced mTBI. Fluorine-18 fluorodeoxyglucose positron emission tomography (F-FDG PET) could detect neuronal function and activity of the injured brain, while MR spectroscopy provides complementary information and assesses metabolic irregularities following injury. This study aims to investigate the effectiveness of combining F-FDG PET with MR spectroscopy to evaluate acute and subacute metabolic cerebral alterations caused by blast-induced mTBI. Thirty-two adult male Sprague-Dawley rats were exposed to a single blast (mTBI group) and 32 rats were not exposed to the blast (sham group), followed by F-FDG PET, MRI, and histological evaluation at baseline, 1-3 h, 1 day, and 7 days post-injury in three separate cohorts. F-FDG uptake showed a transient increase in the amygdala and somatosensory cortex, followed by a gradual return to baseline from day 1 to 7 days post-injury and a continuous rise in the motor cortex. In contrast, decreased F-FDG uptake was seen in the midbrain structures (inferior and superior colliculus). Analysis of MR spectroscopy showed that inflammation marker myo-inositol (Ins), oxidative stress marker glutamine + glutamate (Glx), and hypoxia marker lactate (Lac) levels markedly elevated over time in the somatosensory cortex, while the major osmolyte taurine (Tau) level immediately increased at 1-3 h and 1 day, and then returned to sham level on 7 days post-injury, which could be due to the disruption of the blood-brain barrier. Increased F-FDG uptake and elevated Ins and Glx levels over time were confirmed by histology analysis which showed increased microglial activation and gliosis in the frontal cortex. These results suggest that F-FDG PET and MR spectroscopy can be used together to reflect more comprehensive neuropathological alterations , which could improve our understanding of the complex alterations in the brain after blast-induced mTBI.
大多数爆炸所致轻度创伤性脑损伤（mTBI）患者存在持续的神经功能障碍，而传统结构磁共振成像（MR成像）未发现异常。开发先进的成像方式以检测和了解爆炸所致mTBI的病理生理学情况迫在眉睫。氟代脱氧葡萄糖正电子发射断层扫描（F-FDG PET）能够检测受伤大脑的神经元功能和活性，而磁共振波谱提供补充信息并评估损伤后的代谢异常情况。本研究旨在探讨联合使用F-FDG PET和磁共振波谱来评估爆炸所致mTBI引起的急性和亚急性脑代谢改变的有效性。将32只成年雄性Sprague-Dawley大鼠暴露于单次爆炸（mTBI组），32只大鼠未暴露于爆炸（假手术组），随后在三个独立的队列中，分别于伤后基线、1 - 3小时、1天和7天进行F-FDG PET、MRI及组织学评估。F-FDG摄取在杏仁核和体感皮层呈现短暂增加，随后在伤后1天至7天逐渐恢复至基线水平，而运动皮层则持续上升。相比之下，中脑结构（下丘和上丘）的F-FDG摄取减少。磁共振波谱分析显示，体感皮层中炎症标志物肌醇（Ins）、氧化应激标志物谷氨酰胺+谷氨酸（Glx）和缺氧标志物乳酸（Lac）水平随时间显著升高，而主要渗透溶质牛磺酸（Tau）水平在1 - 3小时和1天时立即升高，然后在伤后7天恢复至假手术组水平，这可能是由于血脑屏障破坏所致。组织学分析证实了F-FDG摄取增加以及Ins和Glx水平随时间升高，该分析显示额叶皮层中小胶质细胞活化和胶质增生增加。这些结果表明，F-FDG PET和磁共振波谱可联合使用以反映更全面的神经病理改变，这有助于我们更好地理解爆炸所致mTBI后脑内的复杂改变。
